src/gpu/ops/GrAtlasTextOp.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 "src/gpu/ops/GrAtlasTextOp.h"

#include "include/core/SkPoint3.h"
#include "include/private/GrRecordingContext.h"
#include "src/core/SkMathPriv.h"
#include "src/core/SkMatrixPriv.h"
#include "src/core/SkStrikeCache.h"
#include "src/gpu/GrCaps.h"
#include "src/gpu/GrMemoryPool.h"
#include "src/gpu/GrOpFlushState.h"
#include "src/gpu/GrRecordingContextPriv.h"
#include "src/gpu/GrResourceProvider.h"
#include "src/gpu/effects/GrBitmapTextGeoProc.h"
#include "src/gpu/effects/GrDistanceFieldGeoProc.h"
#include "src/gpu/ops/GrSimpleMeshDrawOpHelper.h"
#include "src/gpu/text/GrAtlasManager.h"
#include "src/gpu/text/GrStrikeCache.h"

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

std::unique_ptr<GrAtlasTextOp> GrAtlasTextOp::MakeBitmap(GrRecordingContext* context,
                                                         GrPaint&& paint,
                                                         GrMaskFormat maskFormat,
                                                         int glyphCount,
                                                         bool needsTransform) {
        GrOpMemoryPool* pool = context->priv().opMemoryPool();

        std::unique_ptr<GrAtlasTextOp> op = pool->allocate<GrAtlasTextOp>(std::move(paint));

        switch (maskFormat) {
            case kA8_GrMaskFormat:
                op->fMaskType = kGrayscaleCoverageMask_MaskType;
                break;
            case kA565_GrMaskFormat:
                op->fMaskType = kLCDCoverageMask_MaskType;
                break;
            case kARGB_GrMaskFormat:
                op->fMaskType = kColorBitmapMask_MaskType;
                break;
        }
        op->fNumGlyphs = glyphCount;
        op->fGeoCount = 1;
        op->fLuminanceColor = 0;
        op->fNeedsGlyphTransform = needsTransform;
        return op;
    }

std::unique_ptr<GrAtlasTextOp> GrAtlasTextOp::MakeDistanceField(
                                            GrRecordingContext* context,
                                            GrPaint&& paint,
                                            int glyphCount,
                                            const GrDistanceFieldAdjustTable* distanceAdjustTable,
                                            bool useGammaCorrectDistanceTable,
                                            SkColor luminanceColor,
                                            const SkSurfaceProps& props,
                                            bool isAntiAliased,
                                            bool useLCD) {
        GrOpMemoryPool* pool = context->priv().opMemoryPool();

        std::unique_ptr<GrAtlasTextOp> op = pool->allocate<GrAtlasTextOp>(std::move(paint));

        bool isBGR = SkPixelGeometryIsBGR(props.pixelGeometry());
        bool isLCD = useLCD && SkPixelGeometryIsH(props.pixelGeometry());
        op->fMaskType = !isAntiAliased ? kAliasedDistanceField_MaskType
                                       : isLCD ? (isBGR ? kLCDBGRDistanceField_MaskType
                                                        : kLCDDistanceField_MaskType)
                                               : kGrayscaleDistanceField_MaskType;
        op->fDistanceAdjustTable.reset(SkRef(distanceAdjustTable));
        op->fUseGammaCorrectDistanceTable = useGammaCorrectDistanceTable;
        op->fLuminanceColor = luminanceColor;
        op->fNumGlyphs = glyphCount;
        op->fGeoCount = 1;
        return op;
    }

static const int kDistanceAdjustLumShift = 5;

void GrAtlasTextOp::init() {
    const Geometry& geo = fGeoData[0];
    if (this->usesDistanceFields()) {
        bool isLCD = this->isLCD();

        const SkMatrix& drawMatrix = geo.fDrawMatrix;

        fDFGPFlags = drawMatrix.isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
        fDFGPFlags |= drawMatrix.isScaleTranslate() ? kScaleOnly_DistanceFieldEffectFlag : 0;
        fDFGPFlags |= drawMatrix.hasPerspective() ? kPerspective_DistanceFieldEffectFlag : 0;
        fDFGPFlags |= fUseGammaCorrectDistanceTable ? kGammaCorrect_DistanceFieldEffectFlag : 0;
        fDFGPFlags |= (kAliasedDistanceField_MaskType == fMaskType)
                              ? kAliased_DistanceFieldEffectFlag
                              : 0;

        if (isLCD) {
            fDFGPFlags |= kUseLCD_DistanceFieldEffectFlag;
            fDFGPFlags |=
                    (kLCDBGRDistanceField_MaskType == fMaskType) ? kBGR_DistanceFieldEffectFlag : 0;
        }

        fNeedsGlyphTransform = true;
    }

    SkRect bounds;
    geo.fBlob->computeSubRunBounds(
            &bounds, *geo.fSubRunPtr, geo.fDrawMatrix, geo.fDrawOrigin, fNeedsGlyphTransform);
    // We don't have tight bounds on the glyph paths in device space. For the purposes of bounds
    // we treat this as a set of non-AA rects rendered with a texture.
    this->setBounds(bounds, HasAABloat::kNo, IsHairline::kNo);
}

void GrAtlasTextOp::visitProxies(const VisitProxyFunc& func) const {
    fProcessors.visitProxies(func);
}

#ifdef SK_DEBUG
SkString GrAtlasTextOp::dumpInfo() const {
    SkString str;

    for (int i = 0; i < fGeoCount; ++i) {
        str.appendf("%d: Color: 0x%08x Trans: %.2f,%.2f\n",
                    i,
                    fGeoData[i].fColor.toBytes_RGBA(),
                    fGeoData[i].fDrawOrigin.x(),
                    fGeoData[i].fDrawOrigin.y());
    }

    str += fProcessors.dumpProcessors();
    str += INHERITED::dumpInfo();
    return str;
}
#endif

GrDrawOp::FixedFunctionFlags GrAtlasTextOp::fixedFunctionFlags() const {
    return FixedFunctionFlags::kNone;
}

GrProcessorSet::Analysis GrAtlasTextOp::finalize(
        const GrCaps& caps, const GrAppliedClip* clip, bool hasMixedSampledCoverage,
        GrClampType clampType) {
    GrProcessorAnalysisCoverage coverage;
    GrProcessorAnalysisColor color;
    if (kColorBitmapMask_MaskType == fMaskType) {
        color.setToUnknown();
    } else {
        color.setToConstant(this->color());
    }
    switch (fMaskType) {
        case kGrayscaleCoverageMask_MaskType:
        case kAliasedDistanceField_MaskType:
        case kGrayscaleDistanceField_MaskType:
            coverage = GrProcessorAnalysisCoverage::kSingleChannel;
            break;
        case kLCDCoverageMask_MaskType:
        case kLCDDistanceField_MaskType:
        case kLCDBGRDistanceField_MaskType:
            coverage = GrProcessorAnalysisCoverage::kLCD;
            break;
        case kColorBitmapMask_MaskType:
            coverage = GrProcessorAnalysisCoverage::kNone;
            break;
    }
    auto analysis = fProcessors.finalize(
            color, coverage, clip, &GrUserStencilSettings::kUnused, hasMixedSampledCoverage, caps,
            clampType, &fGeoData[0].fColor);
    fUsesLocalCoords = analysis.usesLocalCoords();
    return analysis;
}

static void clip_quads(const SkIRect& clipRect, char* currVertex, const char* blobVertices,
                       size_t vertexStride, int glyphCount) {
    for (int i = 0; i < glyphCount; ++i) {
        const SkPoint* blobPositionLT = reinterpret_cast<const SkPoint*>(blobVertices);
        const SkPoint* blobPositionRB =
                reinterpret_cast<const SkPoint*>(blobVertices + 3 * vertexStride);

        // positions for bitmap glyphs are pixel boundary aligned
        SkIRect positionRect = SkIRect::MakeLTRB(SkScalarRoundToInt(blobPositionLT->fX),
                                                 SkScalarRoundToInt(blobPositionLT->fY),
                                                 SkScalarRoundToInt(blobPositionRB->fX),
                                                 SkScalarRoundToInt(blobPositionRB->fY));
        if (clipRect.contains(positionRect)) {
            memcpy(currVertex, blobVertices, 4 * vertexStride);
            currVertex += 4 * vertexStride;
        } else {
            // Pull out some more data that we'll need.
            // In the LCD case the color will be garbage, but we'll overwrite it with the texcoords
            // and it avoids a lot of conditionals.
            auto color = *reinterpret_cast<const SkColor*>(blobVertices + sizeof(SkPoint));
            size_t coordOffset = vertexStride - 2*sizeof(uint16_t);
            auto* blobCoordsLT = reinterpret_cast<const uint16_t*>(blobVertices + coordOffset);
            auto* blobCoordsRB = reinterpret_cast<const uint16_t*>(blobVertices + 3 * vertexStride +
                                                                   coordOffset);
            // Pull out the texel coordinates and texture index bits
            uint16_t coordsRectL = blobCoordsLT[0] >> 1;
            uint16_t coordsRectT = blobCoordsLT[1] >> 1;
            uint16_t coordsRectR = blobCoordsRB[0] >> 1;
            uint16_t coordsRectB = blobCoordsRB[1] >> 1;
            uint16_t pageIndexX = blobCoordsLT[0] & 0x1;
            uint16_t pageIndexY = blobCoordsLT[1] & 0x1;

            int positionRectWidth = positionRect.width();
            int positionRectHeight = positionRect.height();
            SkASSERT(positionRectWidth == (coordsRectR - coordsRectL));
            SkASSERT(positionRectHeight == (coordsRectB - coordsRectT));

            // Clip position and texCoords to the clipRect
            unsigned int delta;
            delta = SkTMin(SkTMax(clipRect.fLeft - positionRect.fLeft, 0), positionRectWidth);
            coordsRectL += delta;
            positionRect.fLeft += delta;

            delta = SkTMin(SkTMax(clipRect.fTop - positionRect.fTop, 0), positionRectHeight);
            coordsRectT += delta;
            positionRect.fTop += delta;

            delta = SkTMin(SkTMax(positionRect.fRight - clipRect.fRight, 0), positionRectWidth);
            coordsRectR -= delta;
            positionRect.fRight -= delta;

            delta = SkTMin(SkTMax(positionRect.fBottom - clipRect.fBottom, 0), positionRectHeight);
            coordsRectB -= delta;
            positionRect.fBottom -= delta;

            // Repack texel coordinates and index
            coordsRectL = coordsRectL << 1 | pageIndexX;
            coordsRectT = coordsRectT << 1 | pageIndexY;
            coordsRectR = coordsRectR << 1 | pageIndexX;
            coordsRectB = coordsRectB << 1 | pageIndexY;

            // Set new positions and coords
            SkPoint* currPosition = reinterpret_cast<SkPoint*>(currVertex);
            currPosition->fX = positionRect.fLeft;
            currPosition->fY = positionRect.fTop;
            *(reinterpret_cast<SkColor*>(currVertex + sizeof(SkPoint))) = color;
            uint16_t* currCoords = reinterpret_cast<uint16_t*>(currVertex + coordOffset);
            currCoords[0] = coordsRectL;
            currCoords[1] = coordsRectT;
            currVertex += vertexStride;

            currPosition = reinterpret_cast<SkPoint*>(currVertex);
            currPosition->fX = positionRect.fLeft;
            currPosition->fY = positionRect.fBottom;
            *(reinterpret_cast<SkColor*>(currVertex + sizeof(SkPoint))) = color;
            currCoords = reinterpret_cast<uint16_t*>(currVertex + coordOffset);
            currCoords[0] = coordsRectL;
            currCoords[1] = coordsRectB;
            currVertex += vertexStride;

            currPosition = reinterpret_cast<SkPoint*>(currVertex);
            currPosition->fX = positionRect.fRight;
            currPosition->fY = positionRect.fTop;
            *(reinterpret_cast<SkColor*>(currVertex + sizeof(SkPoint))) = color;
            currCoords = reinterpret_cast<uint16_t*>(currVertex + coordOffset);
            currCoords[0] = coordsRectR;
            currCoords[1] = coordsRectT;
            currVertex += vertexStride;

            currPosition = reinterpret_cast<SkPoint*>(currVertex);
            currPosition->fX = positionRect.fRight;
            currPosition->fY = positionRect.fBottom;
            *(reinterpret_cast<SkColor*>(currVertex + sizeof(SkPoint))) = color;
            currCoords = reinterpret_cast<uint16_t*>(currVertex + coordOffset);
            currCoords[0] = coordsRectR;
            currCoords[1] = coordsRectB;
            currVertex += vertexStride;
        }

        blobVertices += 4 * vertexStride;
    }
}

void GrAtlasTextOp::onPrepareDraws(Target* target) {
    auto resourceProvider = target->resourceProvider();

    // 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() && !fGeoData[0].fDrawMatrix.invert(&localMatrix)) {
        return;
    }

    GrAtlasManager* atlasManager = target->atlasManager();
    GrStrikeCache* glyphCache = target->glyphCache();

    GrMaskFormat maskFormat = this->maskFormat();

    unsigned int numActiveViews;
    const GrSurfaceProxyView* views = atlasManager->getViews(maskFormat, &numActiveViews);
    if (!views) {
        SkDebugf("Could not allocate backing texture for atlas\n");
        return;
    }
    SkASSERT(views[0].proxy());

    static constexpr int kMaxTextures = GrBitmapTextGeoProc::kMaxTextures;
    static_assert(GrDistanceFieldA8TextGeoProc::kMaxTextures == kMaxTextures);
    static_assert(GrDistanceFieldLCDTextGeoProc::kMaxTextures == kMaxTextures);

    auto fixedDynamicState = target->makeFixedDynamicState(kMaxTextures);
    for (unsigned i = 0; i < numActiveViews; ++i) {
        fixedDynamicState->fPrimitiveProcessorTextures[i] = views[i].proxy();
        // This op does not know its atlas proxies when it is added to a GrOpsTasks, so the proxies
        // don't get added during the visitProxies call. Thus we add them here.
        target->sampledProxyArray()->push_back(views[i].proxy());
    }

    FlushInfo flushInfo;
    flushInfo.fFixedDynamicState = fixedDynamicState;

    bool vmPerspective = fGeoData[0].fDrawMatrix.hasPerspective();
    if (this->usesDistanceFields()) {
        flushInfo.fGeometryProcessor = this->setupDfProcessor(target->allocator(),
                                                              *target->caps().shaderCaps(),
                                                              views, numActiveViews);
    } else {
        auto filter = fNeedsGlyphTransform ? GrSamplerState::Filter::kBilerp
                                           : GrSamplerState::Filter::kNearest;
        flushInfo.fGeometryProcessor = GrBitmapTextGeoProc::Make(
                target->allocator(), *target->caps().shaderCaps(), this->color(), false, views,
                numActiveViews, filter, maskFormat, localMatrix, vmPerspective);
    }

    int vertexStride = (int)flushInfo.fGeometryProcessor->vertexStride();

    // Ensure we don't request an insanely large contiguous vertex allocation.
    static const int kMaxVertexBytes = GrBufferAllocPool::kDefaultBufferSize;
    const int quadSize = vertexStride * kVerticesPerGlyph;
    const int maxQuadsPerBuffer = kMaxVertexBytes / quadSize;

    // Where the quad buffer begins and ends relative to totalGlyphsRegened.
    int quadBufferBegin = 0;
    int quadBufferEnd = std::min(this->numGlyphs(), maxQuadsPerBuffer);

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

    // totalGlyphsRegened is all the glyphs for the op [0, this->numGlyphs()). The subRun glyph and
    // quad buffer indices are calculated from this.
    int totalGlyphsRegened = 0;
    for (int i = 0; i < fGeoCount; i++) {
        const Geometry& args = fGeoData[i];
        auto subRun = args.fSubRunPtr;
        SkASSERT((int)subRun->vertexStride() == vertexStride);

        subRun->updateVerticesColorIfNeeded(args.fColor.toBytes_RGBA());
        subRun->translateVerticesIfNeeded(args.fDrawMatrix, args.fDrawOrigin);

        // TODO4F: Preserve float colors
        GrTextBlob::VertexRegenerator regenerator(
                resourceProvider, args.fSubRunPtr, target->deferredUploadTarget(), glyphCache,
                atlasManager);

        // Where the subRun begins and ends relative to totalGlyphsRegened.
        int subRunBegin = totalGlyphsRegened;
        int subRunEnd = subRunBegin + (int)subRun->fGlyphs.size();

        // Draw all the glyphs in the subRun.
        while (totalGlyphsRegened < subRunEnd) {
            // drawBegin and drawEnd are indices for the subRun on the
            // interval [0, subRun->fGlyphs.size()).
            int drawBegin = totalGlyphsRegened - subRunBegin;
            // drawEnd is either the end of the subRun or the end of the current quad buffer.
            int drawEnd = std::min(subRunEnd, quadBufferEnd) - subRunBegin;
            auto[ok, glyphsRegenerated] = regenerator.regenerate(drawBegin, drawEnd);

            // There was a problem allocating the glyph in the atlas. Bail.
            if(!ok) { return; }

            // Update all the vertices for glyphsRegenerate glyphs.
            if (glyphsRegenerated > 0) {
                int quadBufferIndex = totalGlyphsRegened - quadBufferBegin;
                int subRunIndex = totalGlyphsRegened - subRunBegin;
                auto regeneratedQuadBuffer =
                        SkTAddOffset<char>(vertices, subRun->quadOffset(quadBufferIndex));
                if (args.fClipRect.isEmpty()) {
                    memcpy(regeneratedQuadBuffer,
                           subRun->quadStart(subRunIndex),
                           glyphsRegenerated * quadSize);
                } else {
                    SkASSERT(!vmPerspective);
                    clip_quads(args.fClipRect,
                               regeneratedQuadBuffer,
                               subRun->quadStart(subRunIndex),
                               vertexStride,
                               glyphsRegenerated);
                }
                if (fNeedsGlyphTransform && !args.fDrawMatrix.isIdentity()) {
                    // We always do the distance field view matrix transformation after copying
                    // rather than during blob vertex generation time in the blob as handling
                    // successive arbitrary transformations would be complicated and accumulate
                    // error.
                    if (args.fDrawMatrix.hasPerspective()) {
                        auto* pos = reinterpret_cast<SkPoint3*>(regeneratedQuadBuffer);
                        SkMatrixPriv::MapHomogeneousPointsWithStride(
                                args.fDrawMatrix, pos,
                                vertexStride, pos,
                                vertexStride,
                                glyphsRegenerated * kVerticesPerGlyph);
                    } else {
                        auto* pos = reinterpret_cast<SkPoint*>(regeneratedQuadBuffer);
                        SkMatrixPriv::MapPointsWithStride(args.fDrawMatrix, pos, vertexStride,
                                                          glyphsRegenerated * kVerticesPerGlyph);
                    }
                }
            }

            totalGlyphsRegened += glyphsRegenerated;
            flushInfo.fGlyphsToFlush += glyphsRegenerated;

            // regenerate() has stopped part way through a SubRun. This means that either the atlas
            // or the quad buffer is full or both. There is a case were the flow through
            // the loop is strange. If we run out of quad buffer space at the same time the
            // SubRun ends, then this is not triggered which is the right result for the last
            // SubRun. But, if this is not the last SubRun, then advance to the next SubRun which
            // will process no glyphs, and return to this point where the quad buffer will be
            // expanded.
            if (totalGlyphsRegened != subRunEnd) {
                // Flush if not all glyphs drawn because either the quad buffer is full or the
                // atlas is out of space.
                this->flush(target, &flushInfo);
                if (totalGlyphsRegened == quadBufferEnd) {
                    // Quad buffer is full. Get more buffer.
                    quadBufferBegin = totalGlyphsRegened;
                    int quadBufferSize =
                            std::min(maxQuadsPerBuffer, this->numGlyphs() - totalGlyphsRegened);
                    quadBufferEnd = quadBufferBegin + quadBufferSize;

                    vertices = target->makeVertexSpace(
                            vertexStride,
                            kVerticesPerGlyph * quadBufferSize,
                            &flushInfo.fVertexBuffer,
                            &flushInfo.fVertexOffset);
                    if (!vertices || !flushInfo.fVertexBuffer) {
                        SkDebugf("Could not allocate vertices\n");
                        return;
                    }
                }
            }
        }
    }  // for all geometries
    this->flush(target, &flushInfo);
}

void GrAtlasTextOp::onExecute(GrOpFlushState* flushState, const SkRect& chainBounds) {
    auto pipeline = GrSimpleMeshDrawOpHelper::CreatePipeline(flushState,
                                                             std::move(fProcessors),
                                                             GrPipeline::InputFlags::kNone);

    flushState->executeDrawsAndUploadsForMeshDrawOp(this, chainBounds, pipeline);
}

void GrAtlasTextOp::flush(GrMeshDrawOp::Target* target, FlushInfo* flushInfo) const {
    if (!flushInfo->fGlyphsToFlush) {
        return;
    }

    auto atlasManager = target->atlasManager();

    GrGeometryProcessor* gp = flushInfo->fGeometryProcessor;
    GrMaskFormat maskFormat = this->maskFormat();

    unsigned int numActiveViews;
    const GrSurfaceProxyView* views = atlasManager->getViews(maskFormat, &numActiveViews);
    SkASSERT(views);
    // Something has gone terribly wrong, bail
    if (!views || 0 == numActiveViews) {
        return;
    }
    if (gp->numTextureSamplers() != (int) numActiveViews) {
        // During preparation the number of atlas pages has increased.
        // Update the proxies used in the GP to match.
        for (unsigned i = gp->numTextureSamplers(); i < numActiveViews; ++i) {
            flushInfo->fFixedDynamicState->fPrimitiveProcessorTextures[i] = views[i].proxy();
            // This op does not know its atlas proxies when it is added to a GrOpsTasks, so the
            // proxies don't get added during the visitProxies call. Thus we add them here.
            target->sampledProxyArray()->push_back(views[i].proxy());
            // These will get unreffed when the previously recorded draws destruct.
            for (int d = 0; d < flushInfo->fNumDraws; ++d) {
                flushInfo->fFixedDynamicState->fPrimitiveProcessorTextures[i]->ref();
            }
        }
        if (this->usesDistanceFields()) {
            if (this->isLCD()) {
                reinterpret_cast<GrDistanceFieldLCDTextGeoProc*>(gp)->addNewViews(
                        views, numActiveViews, GrSamplerState::Filter::kBilerp);
            } else {
                reinterpret_cast<GrDistanceFieldA8TextGeoProc*>(gp)->addNewViews(
                        views, numActiveViews, GrSamplerState::Filter::kBilerp);
            }
        } else {
            auto filter = fNeedsGlyphTransform ? GrSamplerState::Filter::kBilerp
                                               : GrSamplerState::Filter::kNearest;
            reinterpret_cast<GrBitmapTextGeoProc*>(gp)->addNewViews(views, numActiveViews, filter);
        }
    }
    int maxGlyphsPerDraw = static_cast<int>(flushInfo->fIndexBuffer->size() / sizeof(uint16_t) / 6);
    GrMesh* mesh = target->allocMesh(GrPrimitiveType::kTriangles);
    mesh->setIndexedPatterned(flushInfo->fIndexBuffer, kIndicesPerGlyph, kVerticesPerGlyph,
                              flushInfo->fGlyphsToFlush, maxGlyphsPerDraw);
    mesh->setVertexData(flushInfo->fVertexBuffer, flushInfo->fVertexOffset);
    target->recordDraw(flushInfo->fGeometryProcessor, mesh, 1, flushInfo->fFixedDynamicState,
                       nullptr, GrPrimitiveType::kTriangles);
    flushInfo->fVertexOffset += kVerticesPerGlyph * flushInfo->fGlyphsToFlush;
    flushInfo->fGlyphsToFlush = 0;
    ++flushInfo->fNumDraws;
}

GrOp::CombineResult GrAtlasTextOp::onCombineIfPossible(GrOp* t, GrRecordingContext::Arenas*,
                                                       const GrCaps& caps) {
    GrAtlasTextOp* that = t->cast<GrAtlasTextOp>();
    if (fProcessors != that->fProcessors) {
        return CombineResult::kCannotCombine;
    }

    if (fMaskType != that->fMaskType) {
        return CombineResult::kCannotCombine;
    }

    const SkMatrix& thisFirstMatrix = fGeoData[0].fDrawMatrix;
    const SkMatrix& thatFirstMatrix = that->fGeoData[0].fDrawMatrix;

    if (this->usesLocalCoords() && !SkMatrixPriv::CheapEqual(thisFirstMatrix, thatFirstMatrix)) {
        return CombineResult::kCannotCombine;
    }

    if (fNeedsGlyphTransform != that->fNeedsGlyphTransform) {
        return CombineResult::kCannotCombine;
    }

    if (fNeedsGlyphTransform &&
        (thisFirstMatrix.hasPerspective() != thatFirstMatrix.hasPerspective())) {
        return CombineResult::kCannotCombine;
    }

    if (this->usesDistanceFields()) {
        if (fDFGPFlags != that->fDFGPFlags) {
            return CombineResult::kCannotCombine;
        }

        if (fLuminanceColor != that->fLuminanceColor) {
            return CombineResult::kCannotCombine;
        }
    } else {
        if (kColorBitmapMask_MaskType == fMaskType && this->color() != that->color()) {
            return CombineResult::kCannotCombine;
        }
    }

    fNumGlyphs += that->numGlyphs();

    // Reallocate space for geo data if necessary and then import that geo's data.
    int newGeoCount = that->fGeoCount + fGeoCount;

    // We reallocate at a rate of 1.5x to try to get better total memory usage
    if (newGeoCount > fGeoDataAllocSize) {
        int newAllocSize = fGeoDataAllocSize + fGeoDataAllocSize / 2;
        while (newAllocSize < newGeoCount) {
            newAllocSize += newAllocSize / 2;
        }
        fGeoData.realloc(newAllocSize);
        fGeoDataAllocSize = newAllocSize;
    }

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

    return CombineResult::kMerged;
}

// TODO trying to figure out why lcd is so whack
// (see comments in GrTextContext::ComputeCanonicalColor)
GrGeometryProcessor* GrAtlasTextOp::setupDfProcessor(SkArenaAlloc* arena,
                                                     const GrShaderCaps& caps,
                                                     const GrSurfaceProxyView* views,
                                                     unsigned int numActiveViews) const {
    bool isLCD = this->isLCD();

    SkMatrix localMatrix = SkMatrix::I();
    if (this->usesLocalCoords()) {
        // If this fails we'll just use I().
        bool result = fGeoData[0].fDrawMatrix.invert(&localMatrix);
        (void)result;
    }

    // see if we need to create a new effect
    if (isLCD) {
        float redCorrection = fDistanceAdjustTable->getAdjustment(
                SkColorGetR(fLuminanceColor) >> kDistanceAdjustLumShift,
                fUseGammaCorrectDistanceTable);
        float greenCorrection = fDistanceAdjustTable->getAdjustment(
                SkColorGetG(fLuminanceColor) >> kDistanceAdjustLumShift,
                fUseGammaCorrectDistanceTable);
        float blueCorrection = fDistanceAdjustTable->getAdjustment(
                SkColorGetB(fLuminanceColor) >> kDistanceAdjustLumShift,
                fUseGammaCorrectDistanceTable);
        GrDistanceFieldLCDTextGeoProc::DistanceAdjust widthAdjust =
                GrDistanceFieldLCDTextGeoProc::DistanceAdjust::Make(
                        redCorrection, greenCorrection, blueCorrection);
        return GrDistanceFieldLCDTextGeoProc::Make(arena, caps, views, numActiveViews,
                                                   GrSamplerState::Filter::kBilerp, widthAdjust,
                                                   fDFGPFlags, localMatrix);
    } else {
#ifdef SK_GAMMA_APPLY_TO_A8
        float correction = 0;
        if (kAliasedDistanceField_MaskType != fMaskType) {
            U8CPU lum = SkColorSpaceLuminance::computeLuminance(SK_GAMMA_EXPONENT,
                                                                fLuminanceColor);
            correction = fDistanceAdjustTable->getAdjustment(lum >> kDistanceAdjustLumShift,
                                                             fUseGammaCorrectDistanceTable);
        }
        return GrDistanceFieldA8TextGeoProc::Make(arena, caps, views, numActiveViews,
                                                  GrSamplerState::Filter::kBilerp, correction,
                                                  fDFGPFlags, localMatrix);
#else
        return GrDistanceFieldA8TextGeoProc::Make(arena, caps, views, numActiveViews,
                                                  GrSamplerState::Filter::kBilerp,
                                                  fDFGPFlags, localMatrix);
#endif
    }
}