src/gpu/GrAtlasTextContext.cpp

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#include "GrAtlasTextContext.h"

#include "GrBatchFontCache.h"
#include "GrBatchFlushState.h"
#include "GrBatchTest.h"
#include "GrBlurUtils.h"
#include "GrDefaultGeoProcFactory.h"
#include "GrDrawContext.h"
#include "GrDrawTarget.h"
#include "GrFontScaler.h"
#include "GrResourceProvider.h"
#include "GrStrokeInfo.h"
#include "GrTextBlobCache.h"
#include "GrTexturePriv.h"
#include "GrVertexBuffer.h"

#include "SkAutoKern.h"
#include "SkColorPriv.h"
#include "SkColorFilter.h"
#include "SkDistanceFieldGen.h"
#include "SkDraw.h"
#include "SkDrawFilter.h"
#include "SkDrawProcs.h"
#include "SkGlyphCache.h"
#include "SkGpuDevice.h"
#include "SkGr.h"
#include "SkPath.h"
#include "SkRTConf.h"
#include "SkStrokeRec.h"
#include "SkTextBlob.h"
#include "SkTextMapStateProc.h"

#include "batches/GrVertexBatch.h"

#include "effects/GrBitmapTextGeoProc.h"
#include "effects/GrDistanceFieldGeoProc.h"

namespace {
static const size_t kLCDTextVASize = sizeof(SkPoint) + sizeof(SkIPoint16);

// position + local coord
static const size_t kColorTextVASize = sizeof(SkPoint) + sizeof(SkIPoint16);

static const size_t kGrayTextVASize = sizeof(SkPoint) + sizeof(GrColor) + sizeof(SkIPoint16);

static const int kMinDFFontSize = 18;
static const int kSmallDFFontSize = 32;
static const int kSmallDFFontLimit = 32;
static const int kMediumDFFontSize = 72;
static const int kMediumDFFontLimit = 72;
static const int kLargeDFFontSize = 162;
#ifdef SK_BUILD_FOR_ANDROID
static const int kLargeDFFontLimit = 384;
#else
static const int kLargeDFFontLimit = 2 * kLargeDFFontSize;
#endif

SkDEBUGCODE(static const int kExpectedDistanceAdjustTableSize = 8;)
static const int kDistanceAdjustLumShift = 5;

static const int kVerticesPerGlyph = 4;
static const int kIndicesPerGlyph = 6;

static size_t get_vertex_stride(GrMaskFormat maskFormat) {
    switch (maskFormat) {
        case kA8_GrMaskFormat:
            return kGrayTextVASize;
        case kARGB_GrMaskFormat:
            return kColorTextVASize;
        default:
            return kLCDTextVASize;
    }
}

static size_t get_vertex_stride_df(GrMaskFormat maskFormat, bool useLCDText) {
    SkASSERT(maskFormat == kA8_GrMaskFormat);
    if (useLCDText) {
        return kLCDTextVASize;
    } else {
        return kGrayTextVASize;
    }
}

static inline GrColor skcolor_to_grcolor_nopremultiply(SkColor c) {
    unsigned r = SkColorGetR(c);
    unsigned g = SkColorGetG(c);
    unsigned b = SkColorGetB(c);
    return GrColorPackRGBA(r, g, b, 0xff);
}

};

GrAtlasTextContext::GrAtlasTextContext(GrContext* context,
                                       GrDrawContext* drawContext,
                                       const SkSurfaceProps& surfaceProps)
    : INHERITED(context, drawContext, surfaceProps), fDistanceAdjustTable(new DistanceAdjustTable) {
    // We overallocate vertices in our textblobs based on the assumption that A8 has the greatest
    // vertexStride
    static_assert(kGrayTextVASize >= kColorTextVASize && kGrayTextVASize >= kLCDTextVASize,
                  "vertex_attribute_changed");
    fCurrStrike = nullptr;
    fCache = context->getTextBlobCache();
}

void GrAtlasTextContext::DistanceAdjustTable::buildDistanceAdjustTable() {

    // This is used for an approximation of the mask gamma hack, used by raster and bitmap
    // text. The mask gamma hack is based off of guessing what the blend color is going to
    // be, and adjusting the mask so that when run through the linear blend will
    // produce the value closest to the desired result. However, in practice this means
    // that the 'adjusted' mask is just increasing or decreasing the coverage of
    // the mask depending on what it is thought it will blit against. For black (on
    // assumed white) this means that coverages are decreased (on a curve). For white (on
    // assumed black) this means that coverages are increased (on a a curve). At
    // middle (perceptual) gray (which could be blit against anything) the coverages
    // remain the same.
    //
    // The idea here is that instead of determining the initial (real) coverage and
    // then adjusting that coverage, we determine an adjusted coverage directly by
    // essentially manipulating the geometry (in this case, the distance to the glyph
    // edge). So for black (on assumed white) this thins a bit; for white (on
    // assumed black) this fake bolds the geometry a bit.
    //
    // The distance adjustment is calculated by determining the actual coverage value which
    // when fed into in the mask gamma table gives us an 'adjusted coverage' value of 0.5. This
    // actual coverage value (assuming it's between 0 and 1) corresponds to a distance from the
    // actual edge. So by subtracting this distance adjustment and computing without the
    // the coverage adjustment we should get 0.5 coverage at the same point.
    //
    // This has several implications:
    //     For non-gray lcd smoothed text, each subpixel essentially is using a
    //     slightly different geometry.
    //
    //     For black (on assumed white) this may not cover some pixels which were
    //     previously covered; however those pixels would have been only slightly
    //     covered and that slight coverage would have been decreased anyway. Also, some pixels
    //     which were previously fully covered may no longer be fully covered.
    //
    //     For white (on assumed black) this may cover some pixels which weren't
    //     previously covered at all.

    int width, height;
    size_t size;

#ifdef SK_GAMMA_CONTRAST
    SkScalar contrast = SK_GAMMA_CONTRAST;
#else
    SkScalar contrast = 0.5f;
#endif
    SkScalar paintGamma = SK_GAMMA_EXPONENT;
    SkScalar deviceGamma = SK_GAMMA_EXPONENT;

    size = SkScalerContext::GetGammaLUTSize(contrast, paintGamma, deviceGamma,
        &width, &height);

    SkASSERT(kExpectedDistanceAdjustTableSize == height);
    fTable = new SkScalar[height];

    SkAutoTArray<uint8_t> data((int)size);
    SkScalerContext::GetGammaLUTData(contrast, paintGamma, deviceGamma, data.get());

    // find the inverse points where we cross 0.5
    // binsearch might be better, but we only need to do this once on creation
    for (int row = 0; row < height; ++row) {
        uint8_t* rowPtr = data.get() + row*width;
        for (int col = 0; col < width - 1; ++col) {
            if (rowPtr[col] <= 127 && rowPtr[col + 1] >= 128) {
                // compute point where a mask value will give us a result of 0.5
                float interp = (127.5f - rowPtr[col]) / (rowPtr[col + 1] - rowPtr[col]);
                float borderAlpha = (col + interp) / 255.f;

                // compute t value for that alpha
                // this is an approximate inverse for smoothstep()
                float t = borderAlpha*(borderAlpha*(4.0f*borderAlpha - 6.0f) + 5.0f) / 3.0f;

                // compute distance which gives us that t value
                const float kDistanceFieldAAFactor = 0.65f; // should match SK_DistanceFieldAAFactor
                float d = 2.0f*kDistanceFieldAAFactor*t - kDistanceFieldAAFactor;

                fTable[row] = d;
                break;
            }
        }
    }
}

GrAtlasTextContext* GrAtlasTextContext::Create(GrContext* context,
                                               GrDrawContext* drawContext,
                                               const SkSurfaceProps& surfaceProps) {
    return new GrAtlasTextContext(context, drawContext, surfaceProps);
}

bool GrAtlasTextContext::canDraw(const GrRenderTarget*,
                                 const GrClip&,
                                 const GrPaint&,
                                 const SkPaint& skPaint,
                                 const SkMatrix& viewMatrix) {
    return this->canDrawAsDistanceFields(skPaint, viewMatrix) ||
           !SkDraw::ShouldDrawTextAsPaths(skPaint, viewMatrix);
}

GrColor GrAtlasTextContext::ComputeCanonicalColor(const SkPaint& paint, bool lcd) {
    GrColor canonicalColor = paint.computeLuminanceColor();
    if (lcd) {
        // This is the correct computation, but there are tons of cases where LCD can be overridden.
        // For now we just regenerate if any run in a textblob has LCD.
        // TODO figure out where all of these overrides are and see if we can incorporate that logic
        // at a higher level *OR* use sRGB
        SkASSERT(false);
        //canonicalColor = SkMaskGamma::CanonicalColor(canonicalColor);
    } else {
        // A8, though can have mixed BMP text but it shouldn't matter because BMP text won't have
        // gamma corrected masks anyways, nor color
        U8CPU lum = SkComputeLuminance(SkColorGetR(canonicalColor),
                                       SkColorGetG(canonicalColor),
                                       SkColorGetB(canonicalColor));
        // reduce to our finite number of bits
        canonicalColor = SkMaskGamma::CanonicalColor(SkColorSetRGB(lum, lum, lum));
    }
    return canonicalColor;
}

// TODO if this function ever shows up in profiling, then we can compute this value when the
// textblob is being built and cache it.  However, for the time being textblobs mostly only have 1
// run so this is not a big deal to compute here.
bool GrAtlasTextContext::HasLCD(const SkTextBlob* blob) {
    SkTextBlob::RunIterator it(blob);
    for (; !it.done(); it.next()) {
        if (it.isLCD()) {
            return true;
        }
    }
    return false;
}

bool GrAtlasTextContext::MustRegenerateBlob(SkScalar* outTransX, SkScalar* outTransY,
                                            const GrAtlasTextBlob& blob, const SkPaint& paint,
                                            GrColor color, const SkMaskFilter::BlurRec& blurRec,
                                            const SkMatrix& viewMatrix, SkScalar x, SkScalar y) {
    // If we have LCD text then our canonical color will be set to transparent, in this case we have
    // to regenerate the blob on any color change
    // We use the grPaint to get any color filter effects
    if (blob.fKey.fCanonicalColor == SK_ColorTRANSPARENT &&
        blob.fPaintColor != color) {
        return true;
    }

    if (blob.fViewMatrix.hasPerspective() != viewMatrix.hasPerspective()) {
        return true;
    }

    if (blob.fViewMatrix.hasPerspective() && !blob.fViewMatrix.cheapEqualTo(viewMatrix)) {
        return true;
    }

    // We only cache one masked version
    if (blob.fKey.fHasBlur &&
        (blob.fBlurRec.fSigma != blurRec.fSigma ||
         blob.fBlurRec.fStyle != blurRec.fStyle ||
         blob.fBlurRec.fQuality != blurRec.fQuality)) {
        return true;
    }

    // Similarly, we only cache one version for each style
    if (blob.fKey.fStyle != SkPaint::kFill_Style &&
        (blob.fStrokeInfo.fFrameWidth != paint.getStrokeWidth() ||
         blob.fStrokeInfo.fMiterLimit != paint.getStrokeMiter() ||
         blob.fStrokeInfo.fJoin != paint.getStrokeJoin())) {
        return true;
    }

    // Mixed blobs must be regenerated.  We could probably figure out a way to do integer scrolls
    // for mixed blobs if this becomes an issue.
    if (blob.hasBitmap() && blob.hasDistanceField()) {
        // Identical viewmatrices and we can reuse in all cases
        if (blob.fViewMatrix.cheapEqualTo(viewMatrix) && x == blob.fX && y == blob.fY) {
            return false;
        }
        return true;
    }

    if (blob.hasBitmap()) {
        if (blob.fViewMatrix.getScaleX() != viewMatrix.getScaleX() ||
            blob.fViewMatrix.getScaleY() != viewMatrix.getScaleY() ||
            blob.fViewMatrix.getSkewX() != viewMatrix.getSkewX() ||
            blob.fViewMatrix.getSkewY() != viewMatrix.getSkewY()) {
            return true;
        }

        // We can update the positions in the cachedtextblobs without regenerating the whole blob,
        // but only for integer translations.
        // This cool bit of math will determine the necessary translation to apply to the already
        // generated vertex coordinates to move them to the correct position
        SkScalar transX = viewMatrix.getTranslateX() +
                          viewMatrix.getScaleX() * (x - blob.fX) +
                          viewMatrix.getSkewX() * (y - blob.fY) -
                          blob.fViewMatrix.getTranslateX();
        SkScalar transY = viewMatrix.getTranslateY() +
                          viewMatrix.getSkewY() * (x - blob.fX) +
                          viewMatrix.getScaleY() * (y - blob.fY) -
                          blob.fViewMatrix.getTranslateY();
        if (!SkScalarIsInt(transX) || !SkScalarIsInt(transY) ) {
            return true;
        }

        (*outTransX) = transX;
        (*outTransY) = transY;
    } else if (blob.hasDistanceField()) {
        // A scale outside of [blob.fMaxMinScale, blob.fMinMaxScale] would result in a different
        // distance field being generated, so we have to regenerate in those cases
        SkScalar newMaxScale = viewMatrix.getMaxScale();
        SkScalar oldMaxScale = blob.fViewMatrix.getMaxScale();
        SkScalar scaleAdjust = newMaxScale / oldMaxScale;
        if (scaleAdjust < blob.fMaxMinScale || scaleAdjust > blob.fMinMaxScale) {
            return true;
        }

        (*outTransX) = x - blob.fX;
        (*outTransY) = y - blob.fY;
    }

    // It is possible that a blob has neither distanceField nor bitmaptext.  This is in the case
    // when all of the runs inside the blob are drawn as paths.  In this case, we always regenerate
    // the blob anyways at flush time, so no need to regenerate explicitly
    return false;
}


inline SkGlyphCache* GrAtlasTextContext::setupCache(GrAtlasTextBlob::Run* run,
                                                    const SkPaint& skPaint,
                                                    const SkMatrix* viewMatrix,
                                                    bool noGamma) {
    skPaint.getScalerContextDescriptor(&run->fDescriptor, fSurfaceProps, viewMatrix, noGamma);
    run->fTypeface.reset(SkSafeRef(skPaint.getTypeface()));
    return SkGlyphCache::DetachCache(run->fTypeface, run->fDescriptor.getDesc());
}

void GrAtlasTextContext::drawTextBlob(GrRenderTarget* rt,
                                      const GrClip& clip, const SkPaint& skPaint,
                                      const SkMatrix& viewMatrix, const SkTextBlob* blob,
                                      SkScalar x, SkScalar y,
                                      SkDrawFilter* drawFilter, const SkIRect& clipBounds) {
    // If we have been abandoned, then don't draw
    if (fContext->abandoned()) {
        return;
    }

    SkAutoTUnref<GrAtlasTextBlob> cacheBlob;
    SkMaskFilter::BlurRec blurRec;
    GrAtlasTextBlob::Key key;
    // It might be worth caching these things, but its not clear at this time
    // TODO for animated mask filters, this will fill up our cache.  We need a safeguard here
    const SkMaskFilter* mf = skPaint.getMaskFilter();
    bool canCache = !(skPaint.getPathEffect() ||
                      (mf && !mf->asABlur(&blurRec)) ||
                      drawFilter);

    if (canCache) {
        bool hasLCD = HasLCD(blob);

        // We canonicalize all non-lcd draws to use kUnknown_SkPixelGeometry
        SkPixelGeometry pixelGeometry = hasLCD ? fSurfaceProps.pixelGeometry() :
                                                 kUnknown_SkPixelGeometry;

        // TODO we want to figure out a way to be able to use the canonical color on LCD text,
        // see the note on ComputeCanonicalColor above.  We pick a dummy value for LCD text to
        // ensure we always match the same key
        GrColor canonicalColor = hasLCD ? SK_ColorTRANSPARENT :
                                          ComputeCanonicalColor(skPaint, hasLCD);

        key.fPixelGeometry = pixelGeometry;
        key.fUniqueID = blob->uniqueID();
        key.fStyle = skPaint.getStyle();
        key.fHasBlur = SkToBool(mf);
        key.fCanonicalColor = canonicalColor;
        cacheBlob.reset(SkSafeRef(fCache->find(key)));
    }

    SkIRect clipRect;
    clip.getConservativeBounds(rt->width(), rt->height(), &clipRect);

    SkScalar transX = 0.f;
    SkScalar transY = 0.f;

    // Though for the time being runs in the textblob can override the paint, they only touch font
    // info.
    GrPaint grPaint;
    if (!SkPaint2GrPaint(fContext, rt, skPaint, viewMatrix, true, &grPaint)) {
        return;
    }

    if (cacheBlob) {
        if (MustRegenerateBlob(&transX, &transY, *cacheBlob, skPaint, grPaint.getColor(), blurRec,
                               viewMatrix, x, y)) {
            // We have to remake the blob because changes may invalidate our masks.
            // TODO we could probably get away reuse most of the time if the pointer is unique,
            // but we'd have to clear the subrun information
            fCache->remove(cacheBlob);
            cacheBlob.reset(SkRef(fCache->createCachedBlob(blob, key, blurRec, skPaint,
                                                           kGrayTextVASize)));
            this->regenerateTextBlob(cacheBlob, skPaint, grPaint.getColor(), viewMatrix,
                                     blob, x, y, drawFilter, clipRect, rt, clip);
        } else {
            // If we can reuse the blob, then make sure we update the blob's viewmatrix, and x/y
            // offsets.  Note, we offset the vertex bounds right before flushing
            cacheBlob->fViewMatrix = viewMatrix;
            cacheBlob->fX = x;
            cacheBlob->fY = y;
            fCache->makeMRU(cacheBlob);
#ifdef CACHE_SANITY_CHECK
            {
                int glyphCount = 0;
                int runCount = 0;
                GrTextBlobCache::BlobGlyphCount(&glyphCount, &runCount, blob);
                SkAutoTUnref<GrAtlasTextBlob> sanityBlob(fCache->createBlob(glyphCount, runCount,
                                                                            kGrayTextVASize));
                GrTextBlobCache::SetupCacheBlobKey(sanityBlob, key, blurRec, skPaint);
                this->regenerateTextBlob(sanityBlob, skPaint, grPaint.getColor(), viewMatrix,
                                         blob, x, y, drawFilter, clipRect, rt, clip);
                GrAtlasTextBlob::AssertEqual(*sanityBlob, *cacheBlob);
            }

#endif
        }
    } else {
        if (canCache) {
            cacheBlob.reset(SkRef(fCache->createCachedBlob(blob, key, blurRec, skPaint,
                                                           kGrayTextVASize)));
        } else {
            cacheBlob.reset(fCache->createBlob(blob, kGrayTextVASize));
        }
        this->regenerateTextBlob(cacheBlob, skPaint, grPaint.getColor(), viewMatrix,
                                 blob, x, y, drawFilter, clipRect, rt, clip);
    }

    this->flush(blob, cacheBlob, rt, skPaint, grPaint, drawFilter,
                clip, viewMatrix, clipBounds, x, y, transX, transY);
}

inline bool GrAtlasTextContext::canDrawAsDistanceFields(const SkPaint& skPaint,
                                                        const SkMatrix& viewMatrix) {
    // TODO: support perspective (need getMaxScale replacement)
    if (viewMatrix.hasPerspective()) {
        return false;
    }

    SkScalar maxScale = viewMatrix.getMaxScale();
    SkScalar scaledTextSize = maxScale*skPaint.getTextSize();
    // Hinted text looks far better at small resolutions
    // Scaling up beyond 2x yields undesireable artifacts
    if (scaledTextSize < kMinDFFontSize || scaledTextSize > kLargeDFFontLimit) {
        return false;
    }

    bool useDFT = fSurfaceProps.isUseDeviceIndependentFonts();
#if SK_FORCE_DISTANCE_FIELD_TEXT
    useDFT = true;
#endif

    if (!useDFT && scaledTextSize < kLargeDFFontSize) {
        return false;
    }

    // rasterizers and mask filters modify alpha, which doesn't
    // translate well to distance
    if (skPaint.getRasterizer() || skPaint.getMaskFilter() ||
        !fContext->caps()->shaderCaps()->shaderDerivativeSupport()) {
        return false;
    }

    // TODO: add some stroking support
    if (skPaint.getStyle() != SkPaint::kFill_Style) {
        return false;
    }

    return true;
}

void GrAtlasTextContext::regenerateTextBlob(GrAtlasTextBlob* cacheBlob,
                                            const SkPaint& skPaint, GrColor color,
                                            const SkMatrix& viewMatrix,
                                            const SkTextBlob* blob, SkScalar x, SkScalar y,
                                            SkDrawFilter* drawFilter, const SkIRect& clipRect,
                                            GrRenderTarget* rt, const GrClip& clip) {
    // The color here is the GrPaint color, and it is used to determine whether we 
    // have to regenerate LCD text blobs.
    // We use this color vs the SkPaint color because it has the colorfilter applied.
    cacheBlob->fPaintColor = color;
    cacheBlob->fViewMatrix = viewMatrix;
    cacheBlob->fX = x;
    cacheBlob->fY = y;

    // Regenerate textblob
    SkPaint runPaint = skPaint;
    SkTextBlob::RunIterator it(blob);
    for (int run = 0; !it.done(); it.next(), run++) {
        int glyphCount = it.glyphCount();
        size_t textLen = glyphCount * sizeof(uint16_t);
        const SkPoint& offset = it.offset();
        // applyFontToPaint() always overwrites the exact same attributes,
        // so it is safe to not re-seed the paint for this reason.
        it.applyFontToPaint(&runPaint);

        if (drawFilter && !drawFilter->filter(&runPaint, SkDrawFilter::kText_Type)) {
            // A false return from filter() means we should abort the current draw.
            runPaint = skPaint;
            continue;
        }

        runPaint.setFlags(FilterTextFlags(fSurfaceProps, runPaint));

        // setup vertex / glyphIndex for the new run
        if (run > 0) {
            PerSubRunInfo& newRun = cacheBlob->fRuns[run].fSubRunInfo.back();
            PerSubRunInfo& lastRun = cacheBlob->fRuns[run - 1].fSubRunInfo.back();

            newRun.fVertexStartIndex = lastRun.fVertexEndIndex;
            newRun.fVertexEndIndex = lastRun.fVertexEndIndex;

            newRun.fGlyphStartIndex = lastRun.fGlyphEndIndex;
            newRun.fGlyphEndIndex = lastRun.fGlyphEndIndex;
        }

        if (this->canDrawAsDistanceFields(runPaint, viewMatrix)) {
            cacheBlob->setHasDistanceField();
            SkPaint dfPaint = runPaint;
            SkScalar textRatio;
            this->initDistanceFieldPaint(cacheBlob, &dfPaint, &textRatio, viewMatrix);
            Run& runIdx = cacheBlob->fRuns[run];
            PerSubRunInfo& subRun = runIdx.fSubRunInfo.back();
            subRun.fUseLCDText = runPaint.isLCDRenderText();
            subRun.fDrawAsDistanceFields = true;

            SkGlyphCache* cache = this->setupCache(&cacheBlob->fRuns[run], dfPaint, nullptr, true);

            SkTDArray<char> fallbackTxt;
            SkTDArray<SkScalar> fallbackPos;
            SkPoint dfOffset;
            int scalarsPerPosition = 2;
            switch (it.positioning()) {
                case SkTextBlob::kDefault_Positioning: {
                    this->internalDrawDFText(cacheBlob, run, cache, dfPaint, color, viewMatrix,
                                             (const char *)it.glyphs(), textLen,
                                             x + offset.x(), y + offset.y(), clipRect, textRatio,
                                             &fallbackTxt, &fallbackPos, &dfOffset, runPaint);
                    break;
                }
                case SkTextBlob::kHorizontal_Positioning: {
                    scalarsPerPosition = 1;
                    dfOffset = SkPoint::Make(x, y + offset.y());
                    this->internalDrawDFPosText(cacheBlob, run, cache, dfPaint, color, viewMatrix,
                                                (const char*)it.glyphs(), textLen, it.pos(),
                                                scalarsPerPosition, dfOffset, clipRect, textRatio,
                                                &fallbackTxt, &fallbackPos);
                    break;
                }
                case SkTextBlob::kFull_Positioning: {
                    dfOffset = SkPoint::Make(x, y);
                    this->internalDrawDFPosText(cacheBlob, run, cache, dfPaint, color, viewMatrix,
                                                (const char*)it.glyphs(), textLen, it.pos(),
                                                scalarsPerPosition, dfOffset, clipRect, textRatio,
                                                &fallbackTxt, &fallbackPos);
                    break;
                }
            }
            if (fallbackTxt.count()) {
                this->fallbackDrawPosText(cacheBlob, run, rt, clip, color, runPaint, viewMatrix,
                                          fallbackTxt, fallbackPos, scalarsPerPosition, dfOffset,
                                          clipRect);
            }

            SkGlyphCache::AttachCache(cache);
        } else if (SkDraw::ShouldDrawTextAsPaths(runPaint, viewMatrix)) {
            cacheBlob->fRuns[run].fDrawAsPaths = true;
        } else {
            cacheBlob->setHasBitmap();
            SkGlyphCache* cache = this->setupCache(&cacheBlob->fRuns[run], runPaint, &viewMatrix,
                                                   false);
            switch (it.positioning()) {
                case SkTextBlob::kDefault_Positioning:
                    this->internalDrawBMPText(cacheBlob, run, cache, runPaint, color, viewMatrix,
                                              (const char *)it.glyphs(), textLen,
                                              x + offset.x(), y + offset.y(), clipRect);
                    break;
                case SkTextBlob::kHorizontal_Positioning:
                    this->internalDrawBMPPosText(cacheBlob, run, cache, runPaint, color, viewMatrix,
                                                 (const char*)it.glyphs(), textLen, it.pos(), 1,
                                                 SkPoint::Make(x, y + offset.y()), clipRect);
                    break;
                case SkTextBlob::kFull_Positioning:
                    this->internalDrawBMPPosText(cacheBlob, run, cache, runPaint, color, viewMatrix,
                                                 (const char*)it.glyphs(), textLen, it.pos(), 2,
                                                 SkPoint::Make(x, y), clipRect);
                    break;
            }
            SkGlyphCache::AttachCache(cache);
        }

        if (drawFilter) {
            // A draw filter may change the paint arbitrarily, so we must re-seed in this case.
            runPaint = skPaint;
        }
    }
}

inline void GrAtlasTextContext::initDistanceFieldPaint(GrAtlasTextBlob* blob,
                                                       SkPaint* skPaint,
                                                       SkScalar* textRatio,
                                                       const SkMatrix& viewMatrix) {
    // getMaxScale doesn't support perspective, so neither do we at the moment
    SkASSERT(!viewMatrix.hasPerspective());
    SkScalar maxScale = viewMatrix.getMaxScale();
    SkScalar textSize = skPaint->getTextSize();
    SkScalar scaledTextSize = textSize;
    // if we have non-unity scale, we need to choose our base text size
    // based on the SkPaint's text size multiplied by the max scale factor
    // TODO: do we need to do this if we're scaling down (i.e. maxScale < 1)?
    if (maxScale > 0 && !SkScalarNearlyEqual(maxScale, SK_Scalar1)) {
        scaledTextSize *= maxScale;
    }

    // We have three sizes of distance field text, and within each size 'bucket' there is a floor
    // and ceiling.  A scale outside of this range would require regenerating the distance fields
    SkScalar dfMaskScaleFloor;
    SkScalar dfMaskScaleCeil;
    if (scaledTextSize <= kSmallDFFontLimit) {
        dfMaskScaleFloor = kMinDFFontSize;
        dfMaskScaleCeil = kSmallDFFontLimit;
        *textRatio = textSize / kSmallDFFontSize;
        skPaint->setTextSize(SkIntToScalar(kSmallDFFontSize));
    } else if (scaledTextSize <= kMediumDFFontLimit) {
        dfMaskScaleFloor = kSmallDFFontLimit;
        dfMaskScaleCeil = kMediumDFFontLimit;
        *textRatio = textSize / kMediumDFFontSize;
        skPaint->setTextSize(SkIntToScalar(kMediumDFFontSize));
    } else {
        dfMaskScaleFloor = kMediumDFFontLimit;
        dfMaskScaleCeil = kLargeDFFontLimit;
        *textRatio = textSize / kLargeDFFontSize;
        skPaint->setTextSize(SkIntToScalar(kLargeDFFontSize));
    }

    // Because there can be multiple runs in the blob, we want the overall maxMinScale, and
    // minMaxScale to make regeneration decisions.  Specifically, we want the maximum minimum scale
    // we can tolerate before we'd drop to a lower mip size, and the minimum maximum scale we can
    // tolerate before we'd have to move to a large mip size.  When we actually test these values
    // we look at the delta in scale between the new viewmatrix and the old viewmatrix, and test
    // against these values to decide if we can reuse or not(ie, will a given scale change our mip
    // level)
    SkASSERT(dfMaskScaleFloor <= scaledTextSize && scaledTextSize <= dfMaskScaleCeil);
    blob->fMaxMinScale = SkMaxScalar(dfMaskScaleFloor / scaledTextSize, blob->fMaxMinScale);
    blob->fMinMaxScale = SkMinScalar(dfMaskScaleCeil / scaledTextSize, blob->fMinMaxScale);

    skPaint->setLCDRenderText(false);
    skPaint->setAutohinted(false);
    skPaint->setHinting(SkPaint::kNormal_Hinting);
    skPaint->setSubpixelText(true);
}

inline void GrAtlasTextContext::fallbackDrawPosText(GrAtlasTextBlob* blob,
                                                    int runIndex,
                                                    GrRenderTarget* rt, const GrClip& clip,
                                                    GrColor color,
                                                    const SkPaint& skPaint,
                                                    const SkMatrix& viewMatrix,
                                                    const SkTDArray<char>& fallbackTxt,
                                                    const SkTDArray<SkScalar>& fallbackPos,
                                                    int scalarsPerPosition,
                                                    const SkPoint& offset,
                                                    const SkIRect& clipRect) {
    SkASSERT(fallbackTxt.count());
    blob->setHasBitmap();
    Run& run = blob->fRuns[runIndex];
    // Push back a new subrun to fill and set the override descriptor
    run.push_back();
    run.fOverrideDescriptor.reset(new SkAutoDescriptor);
    skPaint.getScalerContextDescriptor(run.fOverrideDescriptor,
                                       fSurfaceProps, &viewMatrix, false);
    SkGlyphCache* cache = SkGlyphCache::DetachCache(run.fTypeface,
                                                    run.fOverrideDescriptor->getDesc());
    this->internalDrawBMPPosText(blob, runIndex, cache, skPaint, color, viewMatrix,
                                 fallbackTxt.begin(), fallbackTxt.count(),
                                 fallbackPos.begin(), scalarsPerPosition, offset, clipRect);
    SkGlyphCache::AttachCache(cache);
}

inline GrAtlasTextBlob*
GrAtlasTextContext::setupDFBlob(int glyphCount, const SkPaint& origPaint,
                                const SkMatrix& viewMatrix, SkGlyphCache** cache,
                                SkPaint* dfPaint, SkScalar* textRatio) {
    GrAtlasTextBlob* blob = fCache->createBlob(glyphCount, 1, kGrayTextVASize);

    *dfPaint = origPaint;
    this->initDistanceFieldPaint(blob, dfPaint, textRatio, viewMatrix);
    blob->fViewMatrix = viewMatrix;
    Run& run = blob->fRuns[0];
    PerSubRunInfo& subRun = run.fSubRunInfo.back();
    subRun.fUseLCDText = origPaint.isLCDRenderText();
    subRun.fDrawAsDistanceFields = true;

    *cache = this->setupCache(&blob->fRuns[0], *dfPaint, nullptr, true);
    return blob;
}

inline GrAtlasTextBlob*
GrAtlasTextContext::createDrawTextBlob(GrRenderTarget* rt, const GrClip& clip,
                                       const GrPaint& paint, const SkPaint& skPaint,
                                       const SkMatrix& viewMatrix,
                                       const char text[], size_t byteLength,
                                       SkScalar x, SkScalar y, const SkIRect& regionClipBounds) {
    int glyphCount = skPaint.countText(text, byteLength);
    SkIRect clipRect;
    clip.getConservativeBounds(rt->width(), rt->height(), &clipRect);

    GrAtlasTextBlob* blob;
    if (this->canDrawAsDistanceFields(skPaint, viewMatrix)) {
        SkPaint dfPaint;
        SkScalar textRatio;
        SkGlyphCache* cache;
        blob = this->setupDFBlob(glyphCount, skPaint, viewMatrix, &cache, &dfPaint, &textRatio);

        SkTDArray<char> fallbackTxt;
        SkTDArray<SkScalar> fallbackPos;
        SkPoint offset;
        this->internalDrawDFText(blob, 0, cache, dfPaint, paint.getColor(), viewMatrix, text,
                                 byteLength, x, y, clipRect, textRatio, &fallbackTxt, &fallbackPos,
                                 &offset, skPaint);
        SkGlyphCache::AttachCache(cache);
        if (fallbackTxt.count()) {
            this->fallbackDrawPosText(blob, 0, rt, clip, paint.getColor(), skPaint, viewMatrix, 
                                      fallbackTxt, fallbackPos, 2, offset, clipRect);
        }
    } else {
        blob = fCache->createBlob(glyphCount, 1, kGrayTextVASize);
        blob->fViewMatrix = viewMatrix;

        SkGlyphCache* cache = this->setupCache(&blob->fRuns[0], skPaint, &viewMatrix, false);
        this->internalDrawBMPText(blob, 0, cache, skPaint, paint.getColor(), viewMatrix, text,
                                  byteLength, x, y, clipRect);
        SkGlyphCache::AttachCache(cache);
    }
    return blob;
}

inline GrAtlasTextBlob*
GrAtlasTextContext::createDrawPosTextBlob(GrRenderTarget* rt, const GrClip& clip,
                                          const GrPaint& paint, const SkPaint& skPaint,
                                          const SkMatrix& viewMatrix,
                                          const char text[], size_t byteLength,
                                          const SkScalar pos[], int scalarsPerPosition,
                                          const SkPoint& offset, const SkIRect& regionClipBounds) {
    int glyphCount = skPaint.countText(text, byteLength);

    SkIRect clipRect;
    clip.getConservativeBounds(rt->width(), rt->height(), &clipRect);

    GrAtlasTextBlob* blob;
    if (this->canDrawAsDistanceFields(skPaint, viewMatrix)) {
        SkPaint dfPaint;
        SkScalar textRatio;
        SkGlyphCache* cache;
        blob = this->setupDFBlob(glyphCount, skPaint, viewMatrix, &cache, &dfPaint, &textRatio);

        SkTDArray<char> fallbackTxt;
        SkTDArray<SkScalar> fallbackPos;
        this->internalDrawDFPosText(blob, 0, cache, dfPaint, paint.getColor(), viewMatrix, text,
                                    byteLength, pos, scalarsPerPosition, offset, clipRect,
                                    textRatio, &fallbackTxt, &fallbackPos);
        SkGlyphCache::AttachCache(cache);
        if (fallbackTxt.count()) {
            this->fallbackDrawPosText(blob, 0, rt, clip, paint.getColor(), skPaint, viewMatrix, 
                                      fallbackTxt, fallbackPos, scalarsPerPosition, offset, 
                                      clipRect);
        }
    } else {
        blob = fCache->createBlob(glyphCount, 1, kGrayTextVASize);
        blob->fViewMatrix = viewMatrix;
        SkGlyphCache* cache = this->setupCache(&blob->fRuns[0], skPaint, &viewMatrix, false);
        this->internalDrawBMPPosText(blob, 0, cache, skPaint, paint.getColor(), viewMatrix, text,
                                     byteLength, pos, scalarsPerPosition, offset, clipRect);
        SkGlyphCache::AttachCache(cache);
    }
    return blob;
}

void GrAtlasTextContext::onDrawText(GrRenderTarget* rt,
                                    const GrClip& clip, 
                                    const GrPaint& paint, const SkPaint& skPaint,
                                    const SkMatrix& viewMatrix,
                                    const char text[], size_t byteLength,
                                    SkScalar x, SkScalar y, const SkIRect& regionClipBounds) {
    SkAutoTUnref<GrAtlasTextBlob> blob(
        this->createDrawTextBlob(rt, clip, paint, skPaint, viewMatrix,
                                 text, byteLength, x, y, regionClipBounds));
    this->flush(blob, rt, skPaint, paint, clip, regionClipBounds);
}

void GrAtlasTextContext::onDrawPosText(GrRenderTarget* rt,
                                       const GrClip& clip,
                                       const GrPaint& paint, const SkPaint& skPaint,
                                       const SkMatrix& viewMatrix,
                                       const char text[], size_t byteLength,
                                       const SkScalar pos[], int scalarsPerPosition,
                                       const SkPoint& offset, const SkIRect& regionClipBounds) {
    SkAutoTUnref<GrAtlasTextBlob> blob(
        this->createDrawPosTextBlob(rt, clip, paint, skPaint, viewMatrix,
                                    text, byteLength,
                                    pos, scalarsPerPosition,
                                    offset, regionClipBounds));

    this->flush(blob, rt, skPaint, paint, clip, regionClipBounds);
}

void GrAtlasTextContext::internalDrawBMPText(GrAtlasTextBlob* blob, int runIndex,
                                             SkGlyphCache* cache, const SkPaint& skPaint,
                                             GrColor color,
                                             const SkMatrix& viewMatrix,
                                             const char text[], size_t byteLength,
                                             SkScalar x, SkScalar y, const SkIRect& clipRect) {
    SkASSERT(byteLength == 0 || text != nullptr);

    // nothing to draw
    if (text == nullptr || byteLength == 0) {
        return;
    }

    fCurrStrike = nullptr;
    SkDrawCacheProc glyphCacheProc = skPaint.getDrawCacheProc();

    // Get GrFontScaler from cache
    GrFontScaler* fontScaler = GetGrFontScaler(cache);

    // transform our starting point
    {
        SkPoint loc;
        viewMatrix.mapXY(x, y, &loc);
        x = loc.fX;
        y = loc.fY;
    }

    // need to measure first
    if (skPaint.getTextAlign() != SkPaint::kLeft_Align) {
        SkVector    stopVector;
        MeasureText(cache, glyphCacheProc, text, byteLength, &stopVector);

        SkScalar    stopX = stopVector.fX;
        SkScalar    stopY = stopVector.fY;

        if (skPaint.getTextAlign() == SkPaint::kCenter_Align) {
            stopX = SkScalarHalf(stopX);
            stopY = SkScalarHalf(stopY);
        }
        x -= stopX;
        y -= stopY;
    }

    const char* stop = text + byteLength;

    SkAutoKern autokern;

    SkFixed fxMask = ~0;
    SkFixed fyMask = ~0;
    SkScalar halfSampleX, halfSampleY;
    if (cache->isSubpixel()) {
        halfSampleX = halfSampleY = SkFixedToScalar(SkGlyph::kSubpixelRound);
        SkAxisAlignment baseline = SkComputeAxisAlignmentForHText(viewMatrix);
        if (kX_SkAxisAlignment == baseline) {
            fyMask = 0;
            halfSampleY = SK_ScalarHalf;
        } else if (kY_SkAxisAlignment == baseline) {
            fxMask = 0;
            halfSampleX = SK_ScalarHalf;
        }
    } else {
        halfSampleX = halfSampleY = SK_ScalarHalf;
    }

    Sk48Dot16 fx = SkScalarTo48Dot16(x + halfSampleX);
    Sk48Dot16 fy = SkScalarTo48Dot16(y + halfSampleY);

    while (text < stop) {
        const SkGlyph& glyph = glyphCacheProc(cache, &text, fx & fxMask, fy & fyMask);

        fx += autokern.adjust(glyph);

        if (glyph.fWidth) {
            this->bmpAppendGlyph(blob,
                                 runIndex,
                                 glyph,
                                 Sk48Dot16FloorToInt(fx),
                                 Sk48Dot16FloorToInt(fy),
                                 color,
                                 fontScaler,
                                 clipRect);
        }

        fx += glyph.fAdvanceX;
        fy += glyph.fAdvanceY;
    }
}

void GrAtlasTextContext::internalDrawBMPPosText(GrAtlasTextBlob* blob, int runIndex,
                                                SkGlyphCache* cache, const SkPaint& skPaint,
                                                GrColor color,
                                                const SkMatrix& viewMatrix,
                                                const char text[], size_t byteLength,
                                                const SkScalar pos[], int scalarsPerPosition,
                                                const SkPoint& offset, const SkIRect& clipRect) {
    SkASSERT(byteLength == 0 || text != nullptr);
    SkASSERT(1 == scalarsPerPosition || 2 == scalarsPerPosition);

    // nothing to draw
    if (text == nullptr || byteLength == 0) {
        return;
    }

    fCurrStrike = nullptr;
    SkDrawCacheProc glyphCacheProc = skPaint.getDrawCacheProc();

    // Get GrFontScaler from cache
    GrFontScaler* fontScaler = GetGrFontScaler(cache);

    const char*        stop = text + byteLength;
    SkTextAlignProc    alignProc(skPaint.getTextAlign());
    SkTextMapStateProc tmsProc(viewMatrix, offset, scalarsPerPosition);

    if (cache->isSubpixel()) {
        // maybe we should skip the rounding if linearText is set
        SkAxisAlignment baseline = SkComputeAxisAlignmentForHText(viewMatrix);

        SkFixed fxMask = ~0;
        SkFixed fyMask = ~0;
        SkScalar halfSampleX = SkFixedToScalar(SkGlyph::kSubpixelRound);
        SkScalar halfSampleY = SkFixedToScalar(SkGlyph::kSubpixelRound);
        if (kX_SkAxisAlignment == baseline) {
            fyMask = 0;
            halfSampleY = SK_ScalarHalf;
        } else if (kY_SkAxisAlignment == baseline) {
            fxMask = 0;
            halfSampleX = SK_ScalarHalf;
        }

        if (SkPaint::kLeft_Align == skPaint.getTextAlign()) {
            while (text < stop) {
                SkPoint tmsLoc;
                tmsProc(pos, &tmsLoc);
                Sk48Dot16 fx = SkScalarTo48Dot16(tmsLoc.fX + halfSampleX);
                Sk48Dot16 fy = SkScalarTo48Dot16(tmsLoc.fY + halfSampleY);

                const SkGlyph& glyph = glyphCacheProc(cache, &text,
                                                      fx & fxMask, fy & fyMask);

                if (glyph.fWidth) {
                    this->bmpAppendGlyph(blob,
                                         runIndex,
                                         glyph,
                                         Sk48Dot16FloorToInt(fx),
                                         Sk48Dot16FloorToInt(fy),
                                         color,
                                         fontScaler,
                                         clipRect);
                }
                pos += scalarsPerPosition;
            }
        } else {
            while (text < stop) {
                const char* currentText = text;
                const SkGlyph& metricGlyph = glyphCacheProc(cache, &text, 0, 0);

                if (metricGlyph.fWidth) {
                    SkDEBUGCODE(SkFixed prevAdvX = metricGlyph.fAdvanceX;)
                    SkDEBUGCODE(SkFixed prevAdvY = metricGlyph.fAdvanceY;)
                    SkPoint tmsLoc;
                    tmsProc(pos, &tmsLoc);
                    SkPoint alignLoc;
                    alignProc(tmsLoc, metricGlyph, &alignLoc);

                    Sk48Dot16 fx = SkScalarTo48Dot16(alignLoc.fX + halfSampleX);
                    Sk48Dot16 fy = SkScalarTo48Dot16(alignLoc.fY + halfSampleY);

                    // have to call again, now that we've been "aligned"
                    const SkGlyph& glyph = glyphCacheProc(cache, &currentText,
                                                          fx & fxMask, fy & fyMask);
                    // the assumption is that the metrics haven't changed
                    SkASSERT(prevAdvX == glyph.fAdvanceX);
                    SkASSERT(prevAdvY == glyph.fAdvanceY);
                    SkASSERT(glyph.fWidth);

                    this->bmpAppendGlyph(blob,
                                         runIndex,
                                         glyph,
                                         Sk48Dot16FloorToInt(fx),
                                         Sk48Dot16FloorToInt(fy),
                                         color,
                                         fontScaler,
                                         clipRect);
                }
                pos += scalarsPerPosition;
            }
        }
    } else {    // not subpixel

        if (SkPaint::kLeft_Align == skPaint.getTextAlign()) {
            while (text < stop) {
                // the last 2 parameters are ignored
                const SkGlyph& glyph = glyphCacheProc(cache, &text, 0, 0);

                if (glyph.fWidth) {
                    SkPoint tmsLoc;
                    tmsProc(pos, &tmsLoc);

                    Sk48Dot16 fx = SkScalarTo48Dot16(tmsLoc.fX + SK_ScalarHalf); //halfSampleX;
                    Sk48Dot16 fy = SkScalarTo48Dot16(tmsLoc.fY + SK_ScalarHalf); //halfSampleY;
                    this->bmpAppendGlyph(blob,
                                         runIndex,
                                         glyph,
                                         Sk48Dot16FloorToInt(fx),
                                         Sk48Dot16FloorToInt(fy),
                                         color,
                                         fontScaler,
                                         clipRect);
                }
                pos += scalarsPerPosition;
            }
        } else {
            while (text < stop) {
                // the last 2 parameters are ignored
                const SkGlyph& glyph = glyphCacheProc(cache, &text, 0, 0);

                if (glyph.fWidth) {
                    SkPoint tmsLoc;
                    tmsProc(pos, &tmsLoc);

                    SkPoint alignLoc;
                    alignProc(tmsLoc, glyph, &alignLoc);

                    Sk48Dot16 fx = SkScalarTo48Dot16(alignLoc.fX + SK_ScalarHalf); //halfSampleX;
                    Sk48Dot16 fy = SkScalarTo48Dot16(alignLoc.fY + SK_ScalarHalf); //halfSampleY;
                    this->bmpAppendGlyph(blob,
                                         runIndex,
                                         glyph,
                                         Sk48Dot16FloorToInt(fx),
                                         Sk48Dot16FloorToInt(fy),
                                         color,
                                         fontScaler,
                                         clipRect);
                }
                pos += scalarsPerPosition;
            }
        }
    }
}


void GrAtlasTextContext::internalDrawDFText(GrAtlasTextBlob* blob, int runIndex,
                                            SkGlyphCache* cache, const SkPaint& skPaint,
                                            GrColor color,
                                            const SkMatrix& viewMatrix,
                                            const char text[], size_t byteLength,
                                            SkScalar x, SkScalar y, const SkIRect& clipRect,
                                            SkScalar textRatio,
                                            SkTDArray<char>* fallbackTxt,
                                            SkTDArray<SkScalar>* fallbackPos,
                                            SkPoint* offset,
                                            const SkPaint& origPaint) {
    SkASSERT(byteLength == 0 || text != nullptr);

    // nothing to draw
    if (text == nullptr || byteLength == 0) {
        return;
    }

    SkDrawCacheProc glyphCacheProc = origPaint.getDrawCacheProc();
    SkAutoDescriptor desc;
    origPaint.getScalerContextDescriptor(&desc, fSurfaceProps, nullptr, true);
    SkGlyphCache* origPaintCache = SkGlyphCache::DetachCache(origPaint.getTypeface(),
                                                             desc.getDesc());

    SkTArray<SkScalar> positions;

    const char* textPtr = text;
    SkFixed stopX = 0;
    SkFixed stopY = 0;
    SkFixed origin = 0;
    switch (origPaint.getTextAlign()) {
        case SkPaint::kRight_Align: origin = SK_Fixed1; break;
        case SkPaint::kCenter_Align: origin = SK_FixedHalf; break;
        case SkPaint::kLeft_Align: origin = 0; break;
    }

    SkAutoKern autokern;
    const char* stop = text + byteLength;
    while (textPtr < stop) {
        // don't need x, y here, since all subpixel variants will have the
        // same advance
        const SkGlyph& glyph = glyphCacheProc(origPaintCache, &textPtr, 0, 0);

        SkFixed width = glyph.fAdvanceX + autokern.adjust(glyph);
        positions.push_back(SkFixedToScalar(stopX + SkFixedMul(origin, width)));

        SkFixed height = glyph.fAdvanceY;
        positions.push_back(SkFixedToScalar(stopY + SkFixedMul(origin, height)));

        stopX += width;
        stopY += height;
    }
    SkASSERT(textPtr == stop);

    // now adjust starting point depending on alignment
    SkScalar alignX = SkFixedToScalar(stopX);
    SkScalar alignY = SkFixedToScalar(stopY);
    if (origPaint.getTextAlign() == SkPaint::kCenter_Align) {
        alignX = SkScalarHalf(alignX);
        alignY = SkScalarHalf(alignY);
    } else if (origPaint.getTextAlign() == SkPaint::kLeft_Align) {
        alignX = 0;
        alignY = 0;
    }
    x -= alignX;
    y -= alignY;
    *offset = SkPoint::Make(x, y);

    this->internalDrawDFPosText(blob, runIndex, cache, skPaint, color, viewMatrix, text, byteLength,
                                positions.begin(), 2, *offset, clipRect, textRatio, fallbackTxt,
                                fallbackPos);
    SkGlyphCache::AttachCache(origPaintCache);
}

void GrAtlasTextContext::internalDrawDFPosText(GrAtlasTextBlob* blob, int runIndex,
                                               SkGlyphCache* cache, const SkPaint& skPaint,
                                               GrColor color,
                                               const SkMatrix& viewMatrix,
                                               const char text[], size_t byteLength,
                                               const SkScalar pos[], int scalarsPerPosition,
                                               const SkPoint& offset, const SkIRect& clipRect,
                                               SkScalar textRatio,
                                               SkTDArray<char>* fallbackTxt,
                                               SkTDArray<SkScalar>* fallbackPos) {

    SkASSERT(byteLength == 0 || text != nullptr);
    SkASSERT(1 == scalarsPerPosition || 2 == scalarsPerPosition);

    // nothing to draw
    if (text == nullptr || byteLength == 0) {
        return;
    }

    fCurrStrike = nullptr;

    SkDrawCacheProc glyphCacheProc = skPaint.getDrawCacheProc();
    GrFontScaler* fontScaler = GetGrFontScaler(cache);

    const char* stop = text + byteLength;

    if (SkPaint::kLeft_Align == skPaint.getTextAlign()) {
        while (text < stop) {
            const char* lastText = text;
            // the last 2 parameters are ignored
            const SkGlyph& glyph = glyphCacheProc(cache, &text, 0, 0);

            if (glyph.fWidth) {
                SkScalar x = offset.x() + pos[0];
                SkScalar y = offset.y() + (2 == scalarsPerPosition ? pos[1] : 0);

                if (!this->dfAppendGlyph(blob,
                                         runIndex,
                                         glyph,
                                         x, y, color, fontScaler, clipRect,
                                         textRatio, viewMatrix)) {
                    // couldn't append, send to fallback
                    fallbackTxt->append(SkToInt(text-lastText), lastText);
                    *fallbackPos->append() = pos[0];
                    if (2 == scalarsPerPosition) {
                        *fallbackPos->append() = pos[1];
                    }
                }
            }
            pos += scalarsPerPosition;
        }
    } else {
        SkScalar alignMul = SkPaint::kCenter_Align == skPaint.getTextAlign() ? SK_ScalarHalf
                                                                             : SK_Scalar1;
        while (text < stop) {
            const char* lastText = text;
            // the last 2 parameters are ignored
            const SkGlyph& glyph = glyphCacheProc(cache, &text, 0, 0);

            if (glyph.fWidth) {
                SkScalar x = offset.x() + pos[0];
                SkScalar y = offset.y() + (2 == scalarsPerPosition ? pos[1] : 0);

                SkScalar advanceX = SkFixedToScalar(glyph.fAdvanceX) * alignMul * textRatio;
                SkScalar advanceY = SkFixedToScalar(glyph.fAdvanceY) * alignMul * textRatio;

                if (!this->dfAppendGlyph(blob,
                                         runIndex,
                                         glyph,
                                         x - advanceX, y - advanceY, color,
                                         fontScaler,
                                         clipRect,
                                         textRatio,
                                         viewMatrix)) {
                    // couldn't append, send to fallback
                    fallbackTxt->append(SkToInt(text-lastText), lastText);
                    *fallbackPos->append() = pos[0];
                    if (2 == scalarsPerPosition) {
                        *fallbackPos->append() = pos[1];
                    }
                }
            }
            pos += scalarsPerPosition;
        }
    }
}

void GrAtlasTextContext::bmpAppendGlyph(GrAtlasTextBlob* blob, int runIndex,
                                        const SkGlyph& skGlyph,
                                        int vx, int vy, GrColor color, GrFontScaler* scaler,
                                        const SkIRect& clipRect) {
    Run& run = blob->fRuns[runIndex];
    if (!fCurrStrike) {
        fCurrStrike = fContext->getBatchFontCache()->getStrike(scaler);
    }

    GrGlyph::PackedID id = GrGlyph::Pack(skGlyph.getGlyphID(),
                                         skGlyph.getSubXFixed(),
                                         skGlyph.getSubYFixed(),
                                         GrGlyph::kCoverage_MaskStyle);
    GrGlyph* glyph = fCurrStrike->getGlyph(skGlyph, id, scaler);
    if (!glyph) {
        return;
    }

    int x = vx + glyph->fBounds.fLeft;
    int y = vy + glyph->fBounds.fTop;

    // keep them as ints until we've done the clip-test
    int width = glyph->fBounds.width();
    int height = glyph->fBounds.height();

#if 0
    // Not checking the clip bounds might introduce a performance regression.  However, its not
    // clear if this is still true today with the larger tiles we use in Chrome.  For repositionable
    // blobs, we want to make sure we have all of the glyphs, so clipping them out is not ideal.
    // We could store the cliprect in the key, but then we'd lose the ability to do integer scrolls
    // TODO verify this
    // check if we clipped out
    if (clipRect.quickReject(x, y, x + width, y + height)) {
        return;
    }
#endif

    // If the glyph is too large we fall back to paths
    if (glyph->fTooLargeForAtlas) {
        this->appendGlyphPath(blob, glyph, scaler, skGlyph, SkIntToScalar(vx), SkIntToScalar(vy));
        return;
    }

    GrMaskFormat format = glyph->fMaskFormat;

    PerSubRunInfo* subRun = &run.fSubRunInfo.back();
    if (run.fInitialized && subRun->fMaskFormat != format) {
        subRun = &run.push_back();
        subRun->fStrike.reset(SkRef(fCurrStrike));
    } else if (!run.fInitialized) {
        subRun->fStrike.reset(SkRef(fCurrStrike));
    }

    run.fInitialized = true;

    size_t vertexStride = get_vertex_stride(format);

    SkRect r;
    r.fLeft = SkIntToScalar(x);
    r.fTop = SkIntToScalar(y);
    r.fRight = r.fLeft + SkIntToScalar(width);
    r.fBottom = r.fTop + SkIntToScalar(height);
    subRun->fMaskFormat = format;
    this->appendGlyphCommon(blob, &run, subRun, r, color, vertexStride, kA8_GrMaskFormat == format,
                            glyph);
}

bool GrAtlasTextContext::dfAppendGlyph(GrAtlasTextBlob* blob, int runIndex,
                                       const SkGlyph& skGlyph,
                                       SkScalar sx, SkScalar sy, GrColor color,
                                       GrFontScaler* scaler,
                                       const SkIRect& clipRect,
                                       SkScalar textRatio, const SkMatrix& viewMatrix) {
    Run& run = blob->fRuns[runIndex];
    if (!fCurrStrike) {
        fCurrStrike = fContext->getBatchFontCache()->getStrike(scaler);
    }

    GrGlyph::PackedID id = GrGlyph::Pack(skGlyph.getGlyphID(),
                                         skGlyph.getSubXFixed(),
                                         skGlyph.getSubYFixed(),
                                         GrGlyph::kDistance_MaskStyle);
    GrGlyph* glyph = fCurrStrike->getGlyph(skGlyph, id, scaler);
    if (!glyph) {
        return true;
    }

    // fallback to color glyph support
    if (kA8_GrMaskFormat != glyph->fMaskFormat) {
        return false;
    }

    SkScalar dx = SkIntToScalar(glyph->fBounds.fLeft + SK_DistanceFieldInset);
    SkScalar dy = SkIntToScalar(glyph->fBounds.fTop + SK_DistanceFieldInset);
    SkScalar width = SkIntToScalar(glyph->fBounds.width() - 2 * SK_DistanceFieldInset);
    SkScalar height = SkIntToScalar(glyph->fBounds.height() - 2 * SK_DistanceFieldInset);

    SkScalar scale = textRatio;
    dx *= scale;
    dy *= scale;
    width *= scale;
    height *= scale;
    sx += dx;
    sy += dy;
    SkRect glyphRect = SkRect::MakeXYWH(sx, sy, width, height);

#if 0
    // check if we clipped out
    SkRect dstRect;
    viewMatrix.mapRect(&dstRect, glyphRect);
    if (clipRect.quickReject(SkScalarTruncToInt(dstRect.left()),
                             SkScalarTruncToInt(dstRect.top()),
                             SkScalarTruncToInt(dstRect.right()),
                             SkScalarTruncToInt(dstRect.bottom()))) {
        return true;
    }
#endif

    // TODO combine with the above
    // If the glyph is too large we fall back to paths
    if (glyph->fTooLargeForAtlas) {
        this->appendGlyphPath(blob, glyph, scaler, skGlyph, sx - dx, sy - dy, scale, true);
        return true;
    }

    PerSubRunInfo* subRun = &run.fSubRunInfo.back();
    if (!run.fInitialized) {
        subRun->fStrike.reset(SkRef(fCurrStrike));
    }
    run.fInitialized = true;
    SkASSERT(glyph->fMaskFormat == kA8_GrMaskFormat);
    subRun->fMaskFormat = kA8_GrMaskFormat;

    size_t vertexStride = get_vertex_stride_df(kA8_GrMaskFormat, subRun->fUseLCDText);

    bool useColorVerts = !subRun->fUseLCDText;
    this->appendGlyphCommon(blob, &run, subRun, glyphRect, color, vertexStride, useColorVerts,
                            glyph);
    return true;
}

inline void GrAtlasTextContext::appendGlyphPath(GrAtlasTextBlob* blob, GrGlyph* glyph,
                                                GrFontScaler* scaler, const SkGlyph& skGlyph,
                                                SkScalar x, SkScalar y, SkScalar scale,
                                                bool applyVM) {
    if (nullptr == glyph->fPath) {
        const SkPath* glyphPath = scaler->getGlyphPath(skGlyph);
        if (!glyphPath) {
            return;
        }

        glyph->fPath = new SkPath(*glyphPath);
    }
    blob->fBigGlyphs.push_back(GrAtlasTextBlob::BigGlyph(*glyph->fPath, x, y, scale, applyVM));
}

inline void GrAtlasTextContext::appendGlyphCommon(GrAtlasTextBlob* blob, Run* run,
                                                  Run::SubRunInfo* subRun,
                                                  const SkRect& positions, GrColor color,
                                                  size_t vertexStride, bool useVertexColor,
                                                  GrGlyph* glyph) {
    blob->fGlyphs[subRun->fGlyphEndIndex] = glyph;
    run->fVertexBounds.joinNonEmptyArg(positions);
    run->fColor = color;

    intptr_t vertex = reinterpret_cast<intptr_t>(blob->fVertices + subRun->fVertexEndIndex);

    if (useVertexColor) {
        // V0
        SkPoint* position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fLeft, positions.fTop);
        SkColor* colorPtr = reinterpret_cast<SkColor*>(vertex + sizeof(SkPoint));
        *colorPtr = color;
        vertex += vertexStride;

        // V1
        position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fLeft, positions.fBottom);
        colorPtr = reinterpret_cast<SkColor*>(vertex + sizeof(SkPoint));
        *colorPtr = color;
        vertex += vertexStride;

        // V2
        position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fRight, positions.fBottom);
        colorPtr = reinterpret_cast<SkColor*>(vertex + sizeof(SkPoint));
        *colorPtr = color;
        vertex += vertexStride;

        // V3
        position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fRight, positions.fTop);
        colorPtr = reinterpret_cast<SkColor*>(vertex + sizeof(SkPoint));
        *colorPtr = color;
    } else {
        // V0
        SkPoint* position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fLeft, positions.fTop);
        vertex += vertexStride;

        // V1
        position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fLeft, positions.fBottom);
        vertex += vertexStride;

        // V2
        position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fRight, positions.fBottom);
        vertex += vertexStride;

        // V3
        position = reinterpret_cast<SkPoint*>(vertex);
        position->set(positions.fRight, positions.fTop);
    }

    subRun->fGlyphEndIndex++;
    subRun->fVertexEndIndex += vertexStride * kVerticesPerGlyph;
}

class TextBatch : public GrVertexBatch {
public:
    typedef GrAtlasTextContext::DistanceAdjustTable DistanceAdjustTable;
    typedef GrAtlasTextBlob Blob;
    typedef Blob::Run Run;
    typedef Run::SubRunInfo TextInfo;
    struct Geometry {
        Blob* fBlob;
        int fRun;
        int fSubRun;
        GrColor fColor;
        SkScalar fTransX;
        SkScalar fTransY;
    };

    static TextBatch* CreateBitmap(GrMaskFormat maskFormat, int glyphCount,
                                   GrBatchFontCache* fontCache) {
        TextBatch* batch = new TextBatch;

        batch->initClassID<TextBatch>();
        batch->fFontCache = fontCache;
        switch (maskFormat) {
            case kA8_GrMaskFormat:
                batch->fMaskType = kGrayscaleCoverageMask_MaskType;
                break;
            case kA565_GrMaskFormat:
                batch->fMaskType = kLCDCoverageMask_MaskType;
                break;
            case kARGB_GrMaskFormat:
                batch->fMaskType = kColorBitmapMask_MaskType;
                break;
        }
        batch->fBatch.fNumGlyphs = glyphCount;
        batch->fGeoCount = 1;
        batch->fFilteredColor = 0;
        batch->fFontCache = fontCache;
        batch->fUseBGR = false;
        return batch;
    }

    static TextBatch* CreateDistanceField(int glyphCount, GrBatchFontCache* fontCache,
                                          DistanceAdjustTable* distanceAdjustTable,
                                          SkColor filteredColor, bool isLCD,
                                          bool useBGR) {
        TextBatch* batch = new TextBatch;
        batch->initClassID<TextBatch>();
        batch->fFontCache = fontCache;
        batch->fMaskType = isLCD ? kLCDDistanceField_MaskType : kGrayscaleDistanceField_MaskType;
        batch->fDistanceAdjustTable.reset(SkRef(distanceAdjustTable));
        batch->fFilteredColor = filteredColor;
        batch->fUseBGR = useBGR;
        batch->fBatch.fNumGlyphs = glyphCount;
        batch->fGeoCount = 1;
        return batch;
    }

    // to avoid even the initial copy of the struct, we have a getter for the first item which
    // is used to seed the batch with its initial geometry.  After seeding, the client should call
    // init() so the Batch can initialize itself
    Geometry& geometry() { return fGeoData[0]; }

    void init() {
        const Geometry& geo = fGeoData[0];
        fBatch.fColor = geo.fColor;
        fBatch.fViewMatrix = geo.fBlob->fViewMatrix;

        // We don't yet position distance field text on the cpu, so we have to map the vertex bounds
        // into device space
        const Run& run = geo.fBlob->fRuns[geo.fRun];
        if (run.fSubRunInfo[geo.fSubRun].fDrawAsDistanceFields) {
            SkRect bounds = run.fVertexBounds;
            fBatch.fViewMatrix.mapRect(&bounds);
            this->setBounds(bounds);
        } else {
            this->setBounds(run.fVertexBounds);
        }
    }

    const char* name() const override { return "TextBatch"; }

    void getInvariantOutputColor(GrInitInvariantOutput* out) const override {
        if (kColorBitmapMask_MaskType == fMaskType) {
            out->setUnknownFourComponents();
        } else {
            out->setKnownFourComponents(fBatch.fColor);
        }
    }

    void getInvariantOutputCoverage(GrInitInvariantOutput* out) const override {
        switch (fMaskType) {
            case kGrayscaleDistanceField_MaskType:
            case kGrayscaleCoverageMask_MaskType:
                out->setUnknownSingleComponent();
                break;
            case kLCDCoverageMask_MaskType:
            case kLCDDistanceField_MaskType:
                out->setUnknownOpaqueFourComponents();
                out->setUsingLCDCoverage();
                break;
            case kColorBitmapMask_MaskType:
                out->setKnownSingleComponent(0xff);
        }
    }

private:
    void initBatchTracker(const GrPipelineOptimizations& opt) override {
        // Handle any color overrides
        if (!opt.readsColor()) {
            fGeoData[0].fColor = GrColor_ILLEGAL;
        }
        opt.getOverrideColorIfSet(&fGeoData[0].fColor);

        // setup batch properties
        fBatch.fColorIgnored = !opt.readsColor();
        fBatch.fColor = fGeoData[0].fColor;
        fBatch.fUsesLocalCoords = opt.readsLocalCoords();
        fBatch.fCoverageIgnored = !opt.readsCoverage();
    }

    struct FlushInfo {
        SkAutoTUnref<const GrVertexBuffer> fVertexBuffer;
        SkAutoTUnref<const GrIndexBuffer> fIndexBuffer;
        int fGlyphsToFlush;
        int fVertexOffset;
    };

    void onPrepareDraws(Target* target) override {
        // if we have RGB, then we won't have any SkShaders so no need to use a localmatrix.
        // TODO actually only invert if we don't have RGBA
        SkMatrix localMatrix;
        if (this->usesLocalCoords() && !this->viewMatrix().invert(&localMatrix)) {
            SkDebugf("Cannot invert viewmatrix\n");
            return;
        }

        GrTexture* texture = fFontCache->getTexture(this->maskFormat());
        if (!texture) {
            SkDebugf("Could not allocate backing texture for atlas\n");
            return;
        }

        bool usesDistanceFields = this->usesDistanceFields();
        GrMaskFormat maskFormat = this->maskFormat();
        bool isLCD = this->isLCD();

        SkAutoTUnref<const GrGeometryProcessor> gp;
        if (usesDistanceFields) {
            gp.reset(this->setupDfProcessor(this->viewMatrix(), fFilteredColor, this->color(),
                                            texture));
        } else {
            GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode);
            gp.reset(GrBitmapTextGeoProc::Create(this->color(),
                                                 texture,
                                                 params,
                                                 maskFormat,
                                                 localMatrix,
                                                 this->usesLocalCoords()));
        }

        FlushInfo flushInfo;
        flushInfo.fGlyphsToFlush = 0;
        size_t vertexStride = gp->getVertexStride();
        SkASSERT(vertexStride == (usesDistanceFields ?
                                  get_vertex_stride_df(maskFormat, isLCD) :
                                  get_vertex_stride(maskFormat)));

        target->initDraw(gp, this->pipeline());

        int glyphCount = this->numGlyphs();
        const GrVertexBuffer* vertexBuffer;

        void* vertices = target->makeVertexSpace(vertexStride,
                                                 glyphCount * kVerticesPerGlyph,
                                                 &vertexBuffer,
                                                 &flushInfo.fVertexOffset);
        flushInfo.fVertexBuffer.reset(SkRef(vertexBuffer));
        flushInfo.fIndexBuffer.reset(target->resourceProvider()->refQuadIndexBuffer());
        if (!vertices || !flushInfo.fVertexBuffer) {
            SkDebugf("Could not allocate vertices\n");
            return;
        }

        unsigned char* currVertex = reinterpret_cast<unsigned char*>(vertices);

        // We cache some values to avoid going to the glyphcache for the same fontScaler twice
        // in a row
        const SkDescriptor* desc = nullptr;
        SkGlyphCache* cache = nullptr;
        GrFontScaler* scaler = nullptr;
        SkTypeface* typeface = nullptr;

        for (int i = 0; i < fGeoCount; i++) {
            Geometry& args = fGeoData[i];
            Blob* blob = args.fBlob;
            Run& run = blob->fRuns[args.fRun];
            TextInfo& info = run.fSubRunInfo[args.fSubRun];

            uint64_t currentAtlasGen = fFontCache->atlasGeneration(maskFormat);
            bool regenerateTextureCoords = info.fAtlasGeneration != currentAtlasGen ||
                                           info.fStrike->isAbandoned();
            bool regenerateColors;
            if (usesDistanceFields) {
                regenerateColors = !isLCD && run.fColor != args.fColor;
            } else {
                regenerateColors = kA8_GrMaskFormat == maskFormat && run.fColor != args.fColor;
            }
            bool regeneratePositions = args.fTransX != 0.f || args.fTransY != 0.f;
            int glyphCount = info.fGlyphEndIndex - info.fGlyphStartIndex;

            // We regenerate both texture coords and colors in the blob itself, and update the
            // atlas generation.  If we don't end up purging any unused plots, we can avoid
            // regenerating the coords.  We could take a finer grained approach to updating texture
            // coords but its not clear if the extra bookkeeping would offset any gains.
            // To avoid looping over the glyphs twice, we do one loop and conditionally update color
            // or coords as needed.  One final note, if we have to break a run for an atlas eviction
            // then we can't really trust the atlas has all of the correct data.  Atlas evictions
            // should be pretty rare, so we just always regenerate in those cases
            if (regenerateTextureCoords || regenerateColors || regeneratePositions) {
                // first regenerate texture coordinates / colors if need be
                bool brokenRun = false;

                // Because the GrBatchFontCache may evict the strike a blob depends on using for
                // generating its texture coords, we have to track whether or not the strike has
                // been abandoned.  If it hasn't been abandoned, then we can use the GrGlyph*s as is
                // otherwise we have to get the new strike, and use that to get the correct glyphs.
                // Because we do not have the packed ids, and thus can't look up our glyphs in the
                // new strike, we instead keep our ref to the old strike and use the packed ids from
                // it.  These ids will still be valid as long as we hold the ref.  When we are done
                // updating our cache of the GrGlyph*s, we drop our ref on the old strike
                bool regenerateGlyphs = false;
                GrBatchTextStrike* strike = nullptr;
                if (regenerateTextureCoords) {
                    info.fBulkUseToken.reset();

                    // We can reuse if we have a valid strike and our descriptors / typeface are the
                    // same
                    const SkDescriptor* newDesc = run.fOverrideDescriptor ?
                                                  run.fOverrideDescriptor->getDesc() :
                                                  run.fDescriptor.getDesc();
                    if (!cache || !SkTypeface::Equal(typeface, run.fTypeface) ||
                                  !(desc->equals(*newDesc))) {
                        if (cache) {
                            SkGlyphCache::AttachCache(cache);
                        }
                        desc = newDesc;
                        cache = SkGlyphCache::DetachCache(run.fTypeface, desc);
                        scaler = GrTextContext::GetGrFontScaler(cache);
                        strike = info.fStrike;
                        typeface = run.fTypeface;
                    }

                    if (info.fStrike->isAbandoned()) {
                        regenerateGlyphs = true;
                        strike = fFontCache->getStrike(scaler);
                    } else {
                        strike = info.fStrike;
                    }
                }

                for (int glyphIdx = 0; glyphIdx < glyphCount; glyphIdx++) {
                    if (regenerateTextureCoords) {
                        size_t glyphOffset = glyphIdx + info.fGlyphStartIndex;

                        GrGlyph* glyph = blob->fGlyphs[glyphOffset];
                        GrGlyph::PackedID id = glyph->fPackedID;
                        const SkGlyph& skGlyph = scaler->grToSkGlyph(id);
                        if (regenerateGlyphs) {
                            // Get the id from the old glyph, and use the new strike to lookup
                            // the glyph.
                            blob->fGlyphs[glyphOffset] = strike->getGlyph(skGlyph, id, maskFormat,
                                                                          scaler);
                        }
                        glyph = blob->fGlyphs[glyphOffset];
                        SkASSERT(glyph);
                        SkASSERT(id == glyph->fPackedID);
                        // We want to be able to assert this but cannot for testing purposes.
                        // once skbug:4143 has landed we can revist this assert
                        //SkASSERT(glyph->fMaskFormat == this->maskFormat());

                        if (!fFontCache->hasGlyph(glyph) &&
                            !strike->addGlyphToAtlas(target, glyph, scaler, skGlyph, maskFormat)) {
                            this->flush(target, &flushInfo);
                            target->initDraw(gp, this->pipeline());
                            brokenRun = glyphIdx > 0;

                            SkDEBUGCODE(bool success =) strike->addGlyphToAtlas(target,
                                                                                glyph,
                                                                                scaler,
                                                                                skGlyph,
                                                                                maskFormat);
                            SkASSERT(success);
                        }
                        fFontCache->addGlyphToBulkAndSetUseToken(&info.fBulkUseToken, glyph,
                                                                 target->currentToken());

                        // Texture coords are the last vertex attribute so we get a pointer to the
                        // first one and then map with stride in regenerateTextureCoords
                        intptr_t vertex = reinterpret_cast<intptr_t>(blob->fVertices);
                        vertex += info.fVertexStartIndex;
                        vertex += vertexStride * glyphIdx * kVerticesPerGlyph;
                        vertex += vertexStride - sizeof(SkIPoint16);

                        this->regenerateTextureCoords(glyph, vertex, vertexStride);
                    }

                    if (regenerateColors) {
                        intptr_t vertex = reinterpret_cast<intptr_t>(blob->fVertices);
                        vertex += info.fVertexStartIndex;
                        vertex += vertexStride * glyphIdx * kVerticesPerGlyph + sizeof(SkPoint);
                        this->regenerateColors(vertex, vertexStride, args.fColor);
                    }

                    if (regeneratePositions) {
                        intptr_t vertex = reinterpret_cast<intptr_t>(blob->fVertices);
                        vertex += info.fVertexStartIndex;
                        vertex += vertexStride * glyphIdx * kVerticesPerGlyph;
                        SkScalar transX = args.fTransX;
                        SkScalar transY = args.fTransY;
                        this->regeneratePositions(vertex, vertexStride, transX, transY);
                    }
                    flushInfo.fGlyphsToFlush++;
                }

                // We my have changed the color so update it here
                run.fColor = args.fColor;
                if (regenerateTextureCoords) {
                    if (regenerateGlyphs) {
                        info.fStrike.reset(SkRef(strike));
                    }
                    info.fAtlasGeneration = brokenRun ? GrBatchAtlas::kInvalidAtlasGeneration :
                                                        fFontCache->atlasGeneration(maskFormat);
                }
            } else {
                flushInfo.fGlyphsToFlush += glyphCount;

                // set use tokens for all of the glyphs in our subrun.  This is only valid if we
                // have a valid atlas generation
                fFontCache->setUseTokenBulk(info.fBulkUseToken, target->currentToken(), maskFormat);
            }

            // now copy all vertices
            size_t byteCount = info.fVertexEndIndex - info.fVertexStartIndex;
            memcpy(currVertex, blob->fVertices + info.fVertexStartIndex, byteCount);

            currVertex += byteCount;
        }
        // Make sure to attach the last cache if applicable
        if (cache) {
            SkGlyphCache::AttachCache(cache);
        }
        this->flush(target, &flushInfo);
    }

    TextBatch() {} // initialized in factory functions.

    ~TextBatch() {
        for (int i = 0; i < fGeoCount; i++) {
            fGeoData[i].fBlob->unref();
        }
    }

    GrMaskFormat maskFormat() const {
        switch (fMaskType) {
            case kLCDCoverageMask_MaskType:
                return kA565_GrMaskFormat;
            case kColorBitmapMask_MaskType:
                return kARGB_GrMaskFormat;
            case kGrayscaleCoverageMask_MaskType:
            case kGrayscaleDistanceField_MaskType:
            case kLCDDistanceField_MaskType:
                return kA8_GrMaskFormat;
        }
        return kA8_GrMaskFormat; // suppress warning
    }

    bool usesDistanceFields() const {
        return kGrayscaleDistanceField_MaskType == fMaskType ||
               kLCDDistanceField_MaskType == fMaskType;
    }

    bool isLCD() const {
        return kLCDCoverageMask_MaskType == fMaskType ||
               kLCDDistanceField_MaskType == fMaskType;
    }

    void regenerateTextureCoords(GrGlyph* glyph, intptr_t vertex, size_t vertexStride) {
        int width = glyph->fBounds.width();
        int height = glyph->fBounds.height();

        int u0, v0, u1, v1;
        if (this->usesDistanceFields()) {
            u0 = glyph->fAtlasLocation.fX + SK_DistanceFieldInset;
            v0 = glyph->fAtlasLocation.fY + SK_DistanceFieldInset;
            u1 = u0 + width - 2 * SK_DistanceFieldInset;
            v1 = v0 + height - 2 * SK_DistanceFieldInset;
        } else {
            u0 = glyph->fAtlasLocation.fX;
            v0 = glyph->fAtlasLocation.fY;
            u1 = u0 + width;
            v1 = v0 + height;
        }

        SkIPoint16* textureCoords;
        // V0
        textureCoords = reinterpret_cast<SkIPoint16*>(vertex);
        textureCoords->set(u0, v0);
        vertex += vertexStride;

        // V1
        textureCoords = reinterpret_cast<SkIPoint16*>(vertex);
        textureCoords->set(u0, v1);
        vertex += vertexStride;

        // V2
        textureCoords = reinterpret_cast<SkIPoint16*>(vertex);
        textureCoords->set(u1, v1);
        vertex += vertexStride;

        // V3
        textureCoords = reinterpret_cast<SkIPoint16*>(vertex);
        textureCoords->set(u1, v0);
    }

    void regenerateColors(intptr_t vertex, size_t vertexStride, GrColor color) {
        for (int i = 0; i < kVerticesPerGlyph; i++) {
            SkColor* vcolor = reinterpret_cast<SkColor*>(vertex);
            *vcolor = color;
            vertex += vertexStride;
        }
    }

    void regeneratePositions(intptr_t vertex, size_t vertexStride, SkScalar transX,
                             SkScalar transY) {
        for (int i = 0; i < kVerticesPerGlyph; i++) {
            SkPoint* point = reinterpret_cast<SkPoint*>(vertex);
            point->fX += transX;
            point->fY += transY;
            vertex += vertexStride;
        }
    }

    void flush(GrVertexBatch::Target* target, FlushInfo* flushInfo) {
        GrVertices vertices;
        int maxGlyphsPerDraw = flushInfo->fIndexBuffer->maxQuads();
        vertices.initInstanced(kTriangles_GrPrimitiveType, flushInfo->fVertexBuffer,
                               flushInfo->fIndexBuffer, flushInfo->fVertexOffset,
                               kVerticesPerGlyph, kIndicesPerGlyph, flushInfo->fGlyphsToFlush,
                               maxGlyphsPerDraw);
        target->draw(vertices);
        flushInfo->fVertexOffset += kVerticesPerGlyph * flushInfo->fGlyphsToFlush;
        flushInfo->fGlyphsToFlush = 0;
    }

    GrColor color() const { return fBatch.fColor; }
    const SkMatrix& viewMatrix() const { return fBatch.fViewMatrix; }
    bool usesLocalCoords() const { return fBatch.fUsesLocalCoords; }
    int numGlyphs() const { return fBatch.fNumGlyphs; }

    bool onCombineIfPossible(GrBatch* t, const GrCaps& caps) override {
        TextBatch* that = t->cast<TextBatch>();
        if (!GrPipeline::CanCombine(*this->pipeline(), this->bounds(), *that->pipeline(),
                                    that->bounds(), caps)) {
            return false;
        }

        if (fMaskType != that->fMaskType) {
            return false;
        }

        if (!this->usesDistanceFields()) {
            // TODO we can often batch across LCD text if we have dual source blending and don't
            // have to use the blend constant
            if (kGrayscaleCoverageMask_MaskType != fMaskType && this->color() != that->color()) {
                return false;
            }
            if (this->usesLocalCoords() && !this->viewMatrix().cheapEqualTo(that->viewMatrix())) {
                return false;
            }
        } else {
            if (!this->viewMatrix().cheapEqualTo(that->viewMatrix())) {
                return false;
            }

            if (fFilteredColor != that->fFilteredColor) {
                return false;
            }

            if (fUseBGR != that->fUseBGR) {
                return false;
            }

            // TODO see note above
            if (kLCDDistanceField_MaskType == fMaskType && this->color() != that->color()) {
                return false;
            }
        }

        fBatch.fNumGlyphs += that->numGlyphs();

        // Reallocate space for geo data if necessary and then import that's geo data.
        int newGeoCount = that->fGeoCount + fGeoCount;
        // We assume (and here enforce) that the allocation size is the smallest power of two that
        // is greater than or equal to the number of geometries (and at least
        // kMinGeometryAllocated).
        int newAllocSize = GrNextPow2(newGeoCount);
        int currAllocSize = SkTMax<int>(kMinGeometryAllocated, GrNextPow2(fGeoCount));

        if (newGeoCount > currAllocSize) {
            fGeoData.realloc(newAllocSize);
        }

        memcpy(&fGeoData[fGeoCount], that->fGeoData.get(), that->fGeoCount * sizeof(Geometry));
        // We steal the ref on the blobs from the other TextBatch and set its count to 0 so that
        // it doesn't try to unref them.
#ifdef SK_DEBUG
        for (int i = 0; i < that->fGeoCount; ++i) {
            that->fGeoData.get()[i].fBlob = (Blob*)0x1;
        }
#endif
        that->fGeoCount = 0;
        fGeoCount = newGeoCount;

        this->joinBounds(that->bounds());
        return true;
    }

    // TODO just use class params
    // TODO trying to figure out why lcd is so whack
    GrGeometryProcessor* setupDfProcessor(const SkMatrix& viewMatrix, SkColor filteredColor,
                                          GrColor color, GrTexture* texture) {
        GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kBilerp_FilterMode);
        bool isLCD = this->isLCD();
        // set up any flags
        uint32_t flags = viewMatrix.isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;

        // see if we need to create a new effect
        if (isLCD) {
            flags |= kUseLCD_DistanceFieldEffectFlag;
            flags |= viewMatrix.rectStaysRect() ? kRectToRect_DistanceFieldEffectFlag : 0;
            flags |= fUseBGR ? kBGR_DistanceFieldEffectFlag : 0;

            GrColor colorNoPreMul = skcolor_to_grcolor_nopremultiply(filteredColor);

            float redCorrection =
                (*fDistanceAdjustTable)[GrColorUnpackR(colorNoPreMul) >> kDistanceAdjustLumShift];
            float greenCorrection =
                (*fDistanceAdjustTable)[GrColorUnpackG(colorNoPreMul) >> kDistanceAdjustLumShift];
            float blueCorrection =
                (*fDistanceAdjustTable)[GrColorUnpackB(colorNoPreMul) >> kDistanceAdjustLumShift];
            GrDistanceFieldLCDTextGeoProc::DistanceAdjust widthAdjust =
                GrDistanceFieldLCDTextGeoProc::DistanceAdjust::Make(redCorrection,
                                                                    greenCorrection,
                                                                    blueCorrection);

            return GrDistanceFieldLCDTextGeoProc::Create(color,
                                                         viewMatrix,
                                                         texture,
                                                         params,
                                                         widthAdjust,
                                                         flags,
                                                         this->usesLocalCoords());
        } else {
            flags |= kColorAttr_DistanceFieldEffectFlag;
#ifdef SK_GAMMA_APPLY_TO_A8
            U8CPU lum = SkColorSpaceLuminance::computeLuminance(SK_GAMMA_EXPONENT, filteredColor);
            float correction = (*fDistanceAdjustTable)[lum >> kDistanceAdjustLumShift];
            return GrDistanceFieldA8TextGeoProc::Create(color,
                                                        viewMatrix,
                                                        texture,
                                                        params,
                                                        correction,
                                                        flags,
                                                        this->usesLocalCoords());
#else
            return GrDistanceFieldA8TextGeoProc::Create(color,
                                                        viewMatrix,
                                                        texture,
                                                        params,
                                                        flags,
                                                        this->usesLocalCoords());
#endif
        }

    }

    struct BatchTracker {
        GrColor fColor;
        SkMatrix fViewMatrix;
        bool fUsesLocalCoords;
        bool fColorIgnored;
        bool fCoverageIgnored;
        int fNumGlyphs;
    };

    BatchTracker fBatch;
    // The minimum number of Geometry we will try to allocate.
    enum { kMinGeometryAllocated = 4 };
    SkAutoSTMalloc<kMinGeometryAllocated, Geometry> fGeoData;
    int fGeoCount;

    enum MaskType {
        kGrayscaleCoverageMask_MaskType,
        kLCDCoverageMask_MaskType,
        kColorBitmapMask_MaskType,
        kGrayscaleDistanceField_MaskType,
        kLCDDistanceField_MaskType,
    } fMaskType;
    bool fUseBGR; // fold this into the enum?

    GrBatchFontCache* fFontCache;

    // Distance field properties
    SkAutoTUnref<const DistanceAdjustTable> fDistanceAdjustTable;
    SkColor fFilteredColor;
};

void GrAtlasTextContext::flushRunAsPaths(GrRenderTarget* rt, const SkTextBlob::RunIterator& it, 
                                         const GrClip& clip, const SkPaint& skPaint,
                                         SkDrawFilter* drawFilter, const SkMatrix& viewMatrix,
                                         const SkIRect& clipBounds, SkScalar x, SkScalar y) {
    SkPaint runPaint = skPaint;

    size_t textLen = it.glyphCount() * sizeof(uint16_t);
    const SkPoint& offset = it.offset();

    it.applyFontToPaint(&runPaint);

    if (drawFilter && !drawFilter->filter(&runPaint, SkDrawFilter::kText_Type)) {
        return;
    }

    runPaint.setFlags(FilterTextFlags(fSurfaceProps, runPaint));

    switch (it.positioning()) {
        case SkTextBlob::kDefault_Positioning:
            this->drawTextAsPath(rt, clip, runPaint, viewMatrix,
                                 (const char *)it.glyphs(),
                                 textLen, x + offset.x(), y + offset.y(), clipBounds);
            break;
        case SkTextBlob::kHorizontal_Positioning:
            this->drawPosTextAsPath(rt, clip, runPaint, viewMatrix,
                                    (const char*)it.glyphs(),
                                    textLen, it.pos(), 1, SkPoint::Make(x, y + offset.y()),
                                    clipBounds);
            break;
        case SkTextBlob::kFull_Positioning:
            this->drawPosTextAsPath(rt, clip, runPaint, viewMatrix,
                                    (const char*)it.glyphs(),
                                    textLen, it.pos(), 2, SkPoint::Make(x, y), clipBounds);
            break;
    }
}

inline GrDrawBatch*
GrAtlasTextContext::createBatch(GrAtlasTextBlob* cacheBlob, const PerSubRunInfo& info,
                                int glyphCount, int run, int subRun,
                                GrColor color, SkScalar transX, SkScalar transY,
                                const SkPaint& skPaint) {
    GrMaskFormat format = info.fMaskFormat;
    GrColor subRunColor;
    if (kARGB_GrMaskFormat == format) {
        uint8_t paintAlpha = skPaint.getAlpha();
        subRunColor = SkColorSetARGB(paintAlpha, paintAlpha, paintAlpha, paintAlpha);
    } else {
        subRunColor = color;
    }

    TextBatch* batch;
    if (info.fDrawAsDistanceFields) {
        SkColor filteredColor;
        SkColorFilter* colorFilter = skPaint.getColorFilter();
        if (colorFilter) {
            filteredColor = colorFilter->filterColor(skPaint.getColor());
        } else {
            filteredColor = skPaint.getColor();
        }
        bool useBGR = SkPixelGeometryIsBGR(fSurfaceProps.pixelGeometry());
        batch = TextBatch::CreateDistanceField(glyphCount, fContext->getBatchFontCache(),
                                               fDistanceAdjustTable, filteredColor,
                                               info.fUseLCDText, useBGR);
    } else {
        batch = TextBatch::CreateBitmap(format, glyphCount, fContext->getBatchFontCache());
    }
    TextBatch::Geometry& geometry = batch->geometry();
    geometry.fBlob = SkRef(cacheBlob);
    geometry.fRun = run;
    geometry.fSubRun = subRun;
    geometry.fColor = subRunColor;
    geometry.fTransX = transX;
    geometry.fTransY = transY;
    batch->init();

    return batch;
}

inline void GrAtlasTextContext::flushRun(GrPipelineBuilder* pipelineBuilder,
                                         GrAtlasTextBlob* cacheBlob, int run, GrColor color,
                                         SkScalar transX, SkScalar transY,
                                         const SkPaint& skPaint) {
    for (int subRun = 0; subRun < cacheBlob->fRuns[run].fSubRunInfo.count(); subRun++) {
        const PerSubRunInfo& info = cacheBlob->fRuns[run].fSubRunInfo[subRun];
        int glyphCount = info.fGlyphEndIndex - info.fGlyphStartIndex;
        if (0 == glyphCount) {
            continue;
        }

        SkAutoTUnref<GrDrawBatch> batch(this->createBatch(cacheBlob, info, glyphCount, run,
                                                          subRun, color, transX, transY,
                                                          skPaint));
        fDrawContext->drawBatch(pipelineBuilder, batch);
    }
}

inline void GrAtlasTextContext::flushBigGlyphs(GrAtlasTextBlob* cacheBlob, GrRenderTarget* rt,
                                               const GrClip& clip, const SkPaint& skPaint,
                                               SkScalar transX, SkScalar transY,
                                               const SkIRect& clipBounds) {
    if (!cacheBlob->fBigGlyphs.count()) {
        return;
    }

    for (int i = 0; i < cacheBlob->fBigGlyphs.count(); i++) {
        GrAtlasTextBlob::BigGlyph& bigGlyph = cacheBlob->fBigGlyphs[i];
        bigGlyph.fVx += transX;
        bigGlyph.fVy += transY;
        SkMatrix ctm;
        ctm.setScale(bigGlyph.fScale, bigGlyph.fScale);
        ctm.postTranslate(bigGlyph.fVx, bigGlyph.fVy);
        if (bigGlyph.fApplyVM) {
            ctm.postConcat(cacheBlob->fViewMatrix);
        }

        GrBlurUtils::drawPathWithMaskFilter(fContext, fDrawContext, rt, clip, bigGlyph.fPath,
                                            skPaint, ctm, nullptr, clipBounds, false);
    }
}

void GrAtlasTextContext::flush(const SkTextBlob* blob,
                               GrAtlasTextBlob* cacheBlob,
                               GrRenderTarget* rt,
                               const SkPaint& skPaint,
                               const GrPaint& grPaint,
                               SkDrawFilter* drawFilter,
                               const GrClip& clip,
                               const SkMatrix& viewMatrix,
                               const SkIRect& clipBounds,
                               SkScalar x, SkScalar y,
                               SkScalar transX, SkScalar transY) {
    // We loop through the runs of the blob, flushing each.  If any run is too large, then we flush
    // it as paths
    GrPipelineBuilder pipelineBuilder(grPaint, rt, clip);

    GrColor color = grPaint.getColor();

    SkTextBlob::RunIterator it(blob);
    for (int run = 0; !it.done(); it.next(), run++) {
        if (cacheBlob->fRuns[run].fDrawAsPaths) {
            this->flushRunAsPaths(rt, it, clip, skPaint,
                                  drawFilter, viewMatrix, clipBounds, x, y);
            continue;
        }
        cacheBlob->fRuns[run].fVertexBounds.offset(transX, transY);
        this->flushRun(&pipelineBuilder, cacheBlob, run, color,
                       transX, transY, skPaint);
    }

    // Now flush big glyphs
    this->flushBigGlyphs(cacheBlob, rt, clip, skPaint, transX, transY, clipBounds);
}

void GrAtlasTextContext::flush(GrAtlasTextBlob* cacheBlob,
                               GrRenderTarget* rt,
                               const SkPaint& skPaint,
                               const GrPaint& grPaint,
                               const GrClip& clip,
                               const SkIRect& clipBounds) {
    GrPipelineBuilder pipelineBuilder(grPaint, rt, clip);

    GrColor color = grPaint.getColor();
    for (int run = 0; run < cacheBlob->fRunCount; run++) {
        this->flushRun(&pipelineBuilder, cacheBlob, run, color, 0, 0, skPaint);
    }

    // Now flush big glyphs
    this->flushBigGlyphs(cacheBlob, rt, clip, skPaint, 0, 0, clipBounds);
}

///////////////////////////////////////////////////////////////////////////////////////////////////

#ifdef GR_TEST_UTILS

DRAW_BATCH_TEST_DEFINE(TextBlobBatch) {
    static uint32_t gContextID = SK_InvalidGenID;
    static GrAtlasTextContext* gTextContext = nullptr;
    static SkSurfaceProps gSurfaceProps(SkSurfaceProps::kLegacyFontHost_InitType);

    if (context->uniqueID() != gContextID) {
        gContextID = context->uniqueID();
        delete gTextContext;

        // We don't yet test the fall back to paths in the GrTextContext base class.  This is mostly
        // because we don't really want to have a gpu device here.
        // We enable distance fields by twiddling a knob on the paint
        GrDrawContext* drawContext = context->drawContext(&gSurfaceProps);

        gTextContext = GrAtlasTextContext::Create(context, drawContext, gSurfaceProps);
    }

    // create dummy render target
    GrSurfaceDesc desc;
    desc.fFlags = kRenderTarget_GrSurfaceFlag;
    desc.fWidth = 1024;
    desc.fHeight = 1024;
    desc.fConfig = kRGBA_8888_GrPixelConfig;
    desc.fSampleCnt = 0;
    SkAutoTUnref<GrTexture> texture(context->textureProvider()->createTexture(desc, true, nullptr, 0));
    SkASSERT(texture);
    SkASSERT(nullptr != texture->asRenderTarget());
    GrRenderTarget* rt = texture->asRenderTarget();

    // Setup dummy SkPaint / GrPaint
    GrColor color = GrRandomColor(random);
    SkMatrix viewMatrix = GrTest::TestMatrixInvertible(random);
    SkPaint skPaint;
    skPaint.setColor(color);
    skPaint.setLCDRenderText(random->nextBool());
    skPaint.setAntiAlias(skPaint.isLCDRenderText() ? true : random->nextBool());
    skPaint.setSubpixelText(random->nextBool());

    GrPaint grPaint;
    if (!SkPaint2GrPaint(context, rt, skPaint, viewMatrix, true, &grPaint)) {
        SkFAIL("couldn't convert paint\n");
    }

    const char* text = "The quick brown fox jumps over the lazy dog.";
    int textLen = (int)strlen(text);

    // Setup clip
    GrClip clip;
    SkIRect noClip = SkIRect::MakeLargest();

    // right now we don't handle textblobs, nor do we handle drawPosText.  Since we only
    // intend to test the batch with this unit test, that is okay.
    SkAutoTUnref<GrAtlasTextBlob> blob(
            gTextContext->createDrawTextBlob(rt, clip, grPaint, skPaint, viewMatrix, text,
                                             static_cast<size_t>(textLen), 0, 0, noClip));

    SkScalar transX = static_cast<SkScalar>(random->nextU());
    SkScalar transY = static_cast<SkScalar>(random->nextU());
    const GrAtlasTextBlob::Run::SubRunInfo& info = blob->fRuns[0].fSubRunInfo[0];
    return gTextContext->createBatch(blob, info, textLen, 0, 0, color, transX, transY, skPaint);
}

#endif