src/gpu/SkGpuDevice.cpp

/*
    Copyright 2011 Google Inc.

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

         http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
 */


#include "GrContext.h"
#include "GrTextContext.h"

#include "SkGpuDevice.h"
#include "SkGrTexturePixelRef.h"

#include "SkColorFilter.h"
#include "SkDrawProcs.h"
#include "SkGlyphCache.h"
#include "SkUtils.h"

#define CACHE_LAYER_TEXTURES 1

#if 0
    extern bool (*gShouldDrawProc)();
    #define CHECK_SHOULD_DRAW(draw)                             \
        do {                                                    \
            if (gShouldDrawProc && !gShouldDrawProc()) return;  \
            this->prepareRenderTarget(draw);                    \
        } while (0)
#else
    #define CHECK_SHOULD_DRAW(draw) this->prepareRenderTarget(draw)
#endif

// we use the same texture slot on GrPaint for bitmaps and shaders
// (since drawBitmap, drawSprite, and drawDevice ignore skia's shader)
enum {
    kBitmapTextureIdx = 0,
    kShaderTextureIdx = 0
};


#define MAX_BLUR_SIGMA 4.0f
// FIXME:  This value comes from from SkBlurMaskFilter.cpp.
// Should probably be put in a common header someplace.
#define MAX_BLUR_RADIUS SkIntToScalar(128)
// This constant approximates the scaling done in the software path's
// "high quality" mode, in SkBlurMask::Blur() (1 / sqrt(3)).
// IMHO, it actually should be 1:  we blur "less" than we should do
// according to the CSS and canvas specs, simply because Safari does the same.
// Firefox used to do the same too, until 4.0 where they fixed it.  So at some
// point we should probably get rid of these scaling constants and rebaseline
// all the blur tests.
#define BLUR_SIGMA_SCALE 0.6f
///////////////////////////////////////////////////////////////////////////////

SkGpuDevice::SkAutoCachedTexture::
             SkAutoCachedTexture(SkGpuDevice* device,
                                 const SkBitmap& bitmap,
                                 const GrSamplerState& sampler,
                                 GrTexture** texture) {
    GrAssert(texture);
    *texture = this->set(device, bitmap, sampler);
}

SkGpuDevice::SkAutoCachedTexture::SkAutoCachedTexture() {
}

GrTexture* SkGpuDevice::SkAutoCachedTexture::set(SkGpuDevice* device,
                                                 const SkBitmap& bitmap,
                                                 const GrSamplerState& sampler) {
    if (fTex.texture()) {
        fDevice->unlockCachedTexture(fTex);
    }
    fDevice = device;
    GrTexture* texture = (GrTexture*)bitmap.getTexture();
    if (texture) {
        // return the native texture
        fTex.reset();
    } else {
        // look it up in our cache
        fTex = device->lockCachedTexture(bitmap, sampler);
        texture = fTex.texture();
    }
    return texture;
}

SkGpuDevice::SkAutoCachedTexture::~SkAutoCachedTexture() {
    if (fTex.texture()) {
        fDevice->unlockCachedTexture(fTex);
    }
}

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

bool gDoTraceDraw;

struct GrSkDrawProcs : public SkDrawProcs {
public:
    GrContext* fContext;
    GrTextContext* fTextContext;
    GrFontScaler* fFontScaler;  // cached in the skia glyphcache
};

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

GrRenderTarget* SkGpuDevice::Current3DApiRenderTarget() {
    return (GrRenderTarget*) -1;
}

static SkBitmap::Config grConfig2skConfig(GrPixelConfig config, bool* isOpaque) {
    switch (config) {
        case kAlpha_8_GrPixelConfig:
            *isOpaque = false;
            return SkBitmap::kA8_Config;
        case kRGB_565_GrPixelConfig:
            *isOpaque = true;
            return SkBitmap::kRGB_565_Config;
        case kRGBA_4444_GrPixelConfig:
            *isOpaque = false;
            return SkBitmap::kARGB_4444_Config;
        case kRGBA_8888_GrPixelConfig:
        case kRGBX_8888_GrPixelConfig:
            *isOpaque = (kRGBX_8888_GrPixelConfig == config);
            return SkBitmap::kARGB_8888_Config;
        default:
            *isOpaque = false;
            return SkBitmap::kNo_Config;
    }
}

static SkBitmap make_bitmap(GrContext* context, GrRenderTarget* renderTarget) {
    if (SkGpuDevice::Current3DApiRenderTarget() == renderTarget) {
        renderTarget = context->createRenderTargetFrom3DApiState();
    }
    GrTexture* texture = renderTarget->asTexture();
    GrPixelConfig config = texture ? texture->config() : kRGBA_8888_GrPixelConfig;

    bool isOpaque;
    SkBitmap bitmap;
    bitmap.setConfig(grConfig2skConfig(config, &isOpaque),
                     renderTarget->width(), renderTarget->height());
    bitmap.setIsOpaque(isOpaque);
    return bitmap;
}

SkGpuDevice::SkGpuDevice(GrContext* context, GrTexture* texture)
: SkDevice(make_bitmap(context, texture->asRenderTarget())) {
    this->initFromRenderTarget(context, texture->asRenderTarget());
}

SkGpuDevice::SkGpuDevice(GrContext* context, GrRenderTarget* renderTarget)
: SkDevice(make_bitmap(context, renderTarget)) {
    this->initFromRenderTarget(context, renderTarget);
}

void SkGpuDevice::initFromRenderTarget(GrContext* context, 
                                       GrRenderTarget* renderTarget) {
    fNeedPrepareRenderTarget = false;
    fDrawProcs = NULL;
    
    fContext = context;
    fContext->ref();
    
    fTexture = NULL;
    fRenderTarget = NULL;
    fNeedClear = false;
    
    if (Current3DApiRenderTarget() == renderTarget) {
        fRenderTarget = fContext->createRenderTargetFrom3DApiState();
    } else {
        GrAssert(NULL != renderTarget);
        fRenderTarget = renderTarget;
        fRenderTarget->ref();
        // if this RT is also a texture, hold a ref on it
        fTexture = fRenderTarget->asTexture();
        SkSafeRef(fTexture);
    }

    SkGrRenderTargetPixelRef* pr = new SkGrRenderTargetPixelRef(fRenderTarget);
    this->setPixelRef(pr, 0)->unref();
}

SkGpuDevice::SkGpuDevice(GrContext* context, SkBitmap::Config config, int width,
                         int height, Usage usage)
: SkDevice(config, width, height, false /*isOpaque*/) {
    fNeedPrepareRenderTarget = false;
    fDrawProcs = NULL;

    fContext = context;
    fContext->ref();

    fTexture = NULL;
    fRenderTarget = NULL;
    fNeedClear = false;

    if (config != SkBitmap::kRGB_565_Config) {
        config = SkBitmap::kARGB_8888_Config;
    }
    SkBitmap bm;
    bm.setConfig(config, width, height);

#if CACHE_LAYER_TEXTURES
    TexType type = (kSaveLayer_Usage == usage) ? 
                            kSaveLayerDeviceRenderTarget_TexType :
                            kDeviceRenderTarget_TexType;
    fCache = this->lockCachedTexture(bm, GrSamplerState::ClampNoFilter(), type);
    fTexture = fCache.texture();
    if (fTexture) {
        SkASSERT(NULL != fTexture->asRenderTarget());
        // hold a ref directly on fTexture (even though fCache has one) to match
        // other constructor paths. Simplifies cleanup.
        fTexture->ref();
    }
#else
    const GrTextureDesc desc = {
        kRenderTarget_GrTextureFlagBit,
        kNone_GrAALevel,
        width,
        height,
        SkGr::Bitmap2PixelConfig(bm)
    };

    fTexture = fContext->createUncachedTexture(desc, NULL, 0);
#endif
    if (NULL != fTexture) {
        fRenderTarget = fTexture->asRenderTarget();
        fRenderTarget->ref();

        GrAssert(NULL != fRenderTarget);

        // we defer the actual clear until our gainFocus()
        fNeedClear = true;

        // wrap the bitmap with a pixelref to expose our texture
        SkGrTexturePixelRef* pr = new SkGrTexturePixelRef(fTexture);
        this->setPixelRef(pr, 0)->unref();
    } else {
        GrPrintf("--- failed to create gpu-offscreen [%d %d]\n",
                 width, height);
        GrAssert(false);
    }
}

SkGpuDevice::~SkGpuDevice() {
    if (fDrawProcs) {
        delete fDrawProcs;
    }

    SkSafeUnref(fTexture);
    SkSafeUnref(fRenderTarget);
    if (fCache.texture()) {
        GrAssert(NULL != fTexture);
        GrAssert(fRenderTarget == fTexture->asRenderTarget());
        fContext->unlockTexture(fCache);
    } 
    fContext->unref();
}

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

void SkGpuDevice::makeRenderTargetCurrent() {
    fContext->setRenderTarget(fRenderTarget);
    fContext->flush(true);
    fNeedPrepareRenderTarget = true;
}

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

bool SkGpuDevice::readPixels(const SkIRect& srcRect, SkBitmap* bitmap) {
    SkIRect bounds;
    bounds.set(0, 0, this->width(), this->height());
    if (!bounds.intersect(srcRect)) {
        return false;
    }

    const int w = bounds.width();
    const int h = bounds.height();
    SkBitmap tmp;
    // note we explicitly specify our rowBytes to be snug (no gap between rows)
    tmp.setConfig(SkBitmap::kARGB_8888_Config, w, h, w * 4);
    if (!tmp.allocPixels()) {
        return false;
    }

    tmp.lockPixels();

    bool read = fContext->readRenderTargetPixels(fRenderTarget,
                                                 bounds.fLeft, bounds.fTop,
                                                 bounds.width(), bounds.height(),
                                                 kRGBA_8888_GrPixelConfig,
                                                 tmp.getPixels());
    tmp.unlockPixels();
    if (!read) {
        return false;
    }

    tmp.swap(*bitmap);
    return true;
}

void SkGpuDevice::writePixels(const SkBitmap& bitmap, int x, int y) {
    SkAutoLockPixels alp(bitmap);
    if (!bitmap.readyToDraw()) {
        return;
    }
    GrPixelConfig config = SkGr::BitmapConfig2PixelConfig(bitmap.config(),
                                                          bitmap.isOpaque());
    fContext->setRenderTarget(fRenderTarget);
    // we aren't setting the clip or matrix, so mark as dirty
    // we don't need to set them for this call and don't have them anyway
    fNeedPrepareRenderTarget = true;

    fContext->writePixels(x, y, bitmap.width(), bitmap.height(),
                          config, bitmap.getPixels(), bitmap.rowBytes());
}

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

static void convert_matrixclip(GrContext* context, const SkMatrix& matrix,
                               const SkClipStack& clipStack,
                               const SkRegion& clipRegion,
                               const SkIPoint& origin) {
    context->setMatrix(matrix);

    SkGrClipIterator iter;
    iter.reset(clipStack);
    const SkIRect& skBounds = clipRegion.getBounds();
    GrRect bounds;
    bounds.setLTRB(GrIntToScalar(skBounds.fLeft),
                   GrIntToScalar(skBounds.fTop),
                   GrIntToScalar(skBounds.fRight),
                   GrIntToScalar(skBounds.fBottom));
    GrClip grc(&iter, GrIntToScalar(-origin.x()), GrIntToScalar(-origin.y()),
               &bounds);
    context->setClip(grc);
}

// call this ever each draw call, to ensure that the context reflects our state,
// and not the state from some other canvas/device
void SkGpuDevice::prepareRenderTarget(const SkDraw& draw) {
    if (fNeedPrepareRenderTarget ||
        fContext->getRenderTarget() != fRenderTarget) {

        fContext->setRenderTarget(fRenderTarget);
        SkASSERT(draw.fClipStack);
        convert_matrixclip(fContext, *draw.fMatrix,
                           *draw.fClipStack, *draw.fClip, this->getOrigin());
        fNeedPrepareRenderTarget = false;
    }
}

void SkGpuDevice::setMatrixClip(const SkMatrix& matrix, const SkRegion& clip,
                                const SkClipStack& clipStack) {
    this->INHERITED::setMatrixClip(matrix, clip, clipStack);
    // We don't need to set them now because the context may not reflect this device.
    fNeedPrepareRenderTarget = true;
}

void SkGpuDevice::gainFocus(SkCanvas* canvas, const SkMatrix& matrix,
                            const SkRegion& clip, const SkClipStack& clipStack) {

    fContext->setRenderTarget(fRenderTarget);

    this->INHERITED::gainFocus(canvas, matrix, clip, clipStack);

    convert_matrixclip(fContext, matrix, clipStack, clip, this->getOrigin());

    if (fNeedClear) {
        fContext->clear(NULL, 0x0);
        fNeedClear = false;
    }
}

bool SkGpuDevice::bindDeviceAsTexture(GrPaint* paint) {
    if (NULL != fTexture) {
        paint->setTexture(kBitmapTextureIdx, fTexture);
        return true;
    }
    return false;
}

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

SK_COMPILE_ASSERT(SkShader::kNone_BitmapType == 0, shader_type_mismatch);
SK_COMPILE_ASSERT(SkShader::kDefault_BitmapType == 1, shader_type_mismatch);
SK_COMPILE_ASSERT(SkShader::kRadial_BitmapType == 2, shader_type_mismatch);
SK_COMPILE_ASSERT(SkShader::kSweep_BitmapType == 3, shader_type_mismatch);
SK_COMPILE_ASSERT(SkShader::kTwoPointRadial_BitmapType == 4,
                  shader_type_mismatch);
SK_COMPILE_ASSERT(SkShader::kLast_BitmapType == 4, shader_type_mismatch);

static const GrSamplerState::SampleMode sk_bmp_type_to_sample_mode[] = {
    (GrSamplerState::SampleMode) -1,                    // kNone_BitmapType
    GrSamplerState::kNormal_SampleMode,                 // kDefault_BitmapType
    GrSamplerState::kRadial_SampleMode,                 // kRadial_BitmapType
    GrSamplerState::kSweep_SampleMode,                  // kSweep_BitmapType
    GrSamplerState::kRadial2_SampleMode,                // kTwoPointRadial_BitmapType
};

bool SkGpuDevice::skPaint2GrPaintNoShader(const SkPaint& skPaint,
                                          bool justAlpha,
                                          GrPaint* grPaint,
                                          bool constantColor) {

    grPaint->fDither    = skPaint.isDither();
    grPaint->fAntiAlias = skPaint.isAntiAlias();

    SkXfermode::Coeff sm = SkXfermode::kOne_Coeff;
    SkXfermode::Coeff dm = SkXfermode::kISA_Coeff;

    SkXfermode* mode = skPaint.getXfermode();
    if (mode) {
        if (!mode->asCoeff(&sm, &dm)) {
            SkDEBUGCODE(SkDebugf("Unsupported xfer mode.\n");)
#if 0
            return false;
#endif
        }
    }
    grPaint->fSrcBlendCoeff = sk_blend_to_grblend(sm);
    grPaint->fDstBlendCoeff = sk_blend_to_grblend(dm);

    if (justAlpha) {
        uint8_t alpha = skPaint.getAlpha();
        grPaint->fColor = GrColorPackRGBA(alpha, alpha, alpha, alpha);
        // justAlpha is currently set to true only if there is a texture,
        // so constantColor should not also be true.
        GrAssert(!constantColor);
    } else {
        grPaint->fColor = SkGr::SkColor2GrColor(skPaint.getColor());
        grPaint->setTexture(kShaderTextureIdx, NULL);
    }
    SkColorFilter* colorFilter = skPaint.getColorFilter();
    SkColor color;
    SkXfermode::Mode filterMode;
    if (colorFilter != NULL && colorFilter->asColorMode(&color, &filterMode)) {
        if (!constantColor) {
            grPaint->fColorFilterColor = SkGr::SkColor2GrColor(color);
            grPaint->fColorFilterXfermode = filterMode;
            return true;
        }
        SkColor filtered = colorFilter->filterColor(skPaint.getColor());
        grPaint->fColor = SkGr::SkColor2GrColor(filtered);
    }
    grPaint->resetColorFilter();
    return true;
}

bool SkGpuDevice::skPaint2GrPaintShader(const SkPaint& skPaint,
                                        SkAutoCachedTexture* act,
                                        const SkMatrix& ctm,
                                        GrPaint* grPaint,
                                        bool constantColor) {

    SkASSERT(NULL != act);

    SkShader* shader = skPaint.getShader();
    if (NULL == shader) {
        return this->skPaint2GrPaintNoShader(skPaint,
                                             false,
                                             grPaint,
                                             constantColor);
    } else if (!this->skPaint2GrPaintNoShader(skPaint, true, grPaint, false)) {
        return false;
    }

    SkBitmap bitmap;
    SkMatrix matrix;
    SkShader::TileMode tileModes[2];
    SkScalar twoPointParams[3];
    SkShader::BitmapType bmptype = shader->asABitmap(&bitmap, &matrix,
                                                     tileModes, twoPointParams);

    GrSamplerState::SampleMode sampleMode = sk_bmp_type_to_sample_mode[bmptype];
    if (-1 == sampleMode) {
        SkShader::GradientInfo info;
        SkColor                color;

        info.fColors = &color;
        info.fColorOffsets = NULL;
        info.fColorCount = 1;
        if (SkShader::kColor_GradientType == shader->asAGradient(&info)) {
            SkPaint copy(skPaint);
            copy.setShader(NULL);
            // modulate the paint alpha by the shader's solid color alpha
            U8CPU newA = SkMulDiv255Round(SkColorGetA(color), copy.getAlpha());
            copy.setColor(SkColorSetA(color, newA));
            return this->skPaint2GrPaintNoShader(copy,
                                                 false,
                                                 grPaint,
                                                 constantColor);
        }
        return false;
    }
    GrSamplerState* sampler = grPaint->getTextureSampler(kShaderTextureIdx);
    sampler->setSampleMode(sampleMode);
    if (skPaint.isFilterBitmap()) {
        sampler->setFilter(GrSamplerState::kBilinear_Filter);
    } else {
        sampler->setFilter(GrSamplerState::kNearest_Filter);
    }
    sampler->setWrapX(sk_tile_mode_to_grwrap(tileModes[0]));
    sampler->setWrapY(sk_tile_mode_to_grwrap(tileModes[1]));
    if (GrSamplerState::kRadial2_SampleMode == sampleMode) {
        sampler->setRadial2Params(twoPointParams[0],
                                  twoPointParams[1],
                                  twoPointParams[2] < 0);
    }

    GrTexture* texture = act->set(this, bitmap, *sampler);
    if (NULL == texture) {
        SkDebugf("Couldn't convert bitmap to texture.\n");
        return false;
    }
    grPaint->setTexture(kShaderTextureIdx, texture);

    // since our texture coords will be in local space, we wack the texture
    // matrix to map them back into 0...1 before we load it
    SkMatrix localM;
    if (shader->getLocalMatrix(&localM)) {
        SkMatrix inverse;
        if (localM.invert(&inverse)) {
            matrix.preConcat(inverse);
        }
    }
    if (SkShader::kDefault_BitmapType == bmptype) {
        GrScalar sx = GrFixedToScalar(GR_Fixed1 / bitmap.width());
        GrScalar sy = GrFixedToScalar(GR_Fixed1 / bitmap.height());
        matrix.postScale(sx, sy);
    } else if (SkShader::kRadial_BitmapType == bmptype) {
        GrScalar s = GrFixedToScalar(GR_Fixed1 / bitmap.width());
        matrix.postScale(s, s);
    }
    sampler->setMatrix(matrix);

    return true;
}

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

class SkPositionSource {
public:
    SkPositionSource(const SkPoint* points, int count)
        : fPoints(points), fCount(count) {}

    int count() const { return fCount; }

    void writeValue(int i, GrPoint* dstPosition) const {
        SkASSERT(i < fCount);
        dstPosition->fX = SkScalarToGrScalar(fPoints[i].fX);
        dstPosition->fY = SkScalarToGrScalar(fPoints[i].fY);
    }
private:
    const SkPoint*  fPoints;
    int             fCount;
};

class SkTexCoordSource {
public:
    SkTexCoordSource(const SkPoint* coords)
        : fCoords(coords) {}

    void writeValue(int i, GrPoint* dstCoord) const {
        dstCoord->fX = SkScalarToGrScalar(fCoords[i].fX);
        dstCoord->fY = SkScalarToGrScalar(fCoords[i].fY);
    }
private:
    const SkPoint*  fCoords;
};

class SkColorSource {
public:
    SkColorSource(const SkColor* colors) : fColors(colors) {}

    void writeValue(int i, GrColor* dstColor) const {
        *dstColor = SkGr::SkColor2GrColor(fColors[i]);
    }
private:
    const SkColor* fColors;
};

class SkIndexSource {
public:
    SkIndexSource(const uint16_t* indices, int count)
        : fIndices(indices), fCount(count) {
    }

    int count() const { return fCount; }

    void writeValue(int i, uint16_t* dstIndex) const {
        *dstIndex = fIndices[i];
    }

private:
    const uint16_t* fIndices;
    int             fCount;
};

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

#if 0 // not currently being used so don't compile,

// can be used for positions or texture coordinates

class SkRectFanSource {
public:
    SkRectFanSource(const SkRect& rect) : fRect(rect) {}

    int count() const { return 4; }

    void writeValue(int i, GrPoint* dstPoint) const {
        SkASSERT(i < 4);
        dstPoint->fX = SkScalarToGrScalar((i % 3) ? fRect.fRight :
                                                    fRect.fLeft);
        dstPoint->fY = SkScalarToGrScalar((i < 2) ? fRect.fTop  :
                                                    fRect.fBottom);
    }
private:
    const SkRect&   fRect;
};

class SkIRectFanSource {
public:
    SkIRectFanSource(const SkIRect& rect) : fRect(rect) {}

    int count() const { return 4; }

    void writeValue(int i, GrPoint* dstPoint) const {
        SkASSERT(i < 4);
        dstPoint->fX = (i % 3) ? GrIntToScalar(fRect.fRight) :
                                 GrIntToScalar(fRect.fLeft);
        dstPoint->fY = (i < 2) ? GrIntToScalar(fRect.fTop)  :
                                 GrIntToScalar(fRect.fBottom);
    }
private:
    const SkIRect&   fRect;
};

class SkMatRectFanSource {
public:
    SkMatRectFanSource(const SkRect& rect, const SkMatrix& matrix)
        : fRect(rect), fMatrix(matrix) {}

    int count() const { return 4; }

    void writeValue(int i, GrPoint* dstPoint) const {
        SkASSERT(i < 4);

#if SK_SCALAR_IS_GR_SCALAR
        fMatrix.mapXY((i % 3) ? fRect.fRight : fRect.fLeft,
                      (i < 2) ? fRect.fTop   : fRect.fBottom,
                      (SkPoint*)dstPoint);
#else
        SkPoint dst;
        fMatrix.mapXY((i % 3) ? fRect.fRight : fRect.fLeft,
                      (i < 2) ? fRect.fTop   : fRect.fBottom,
                      &dst);
        dstPoint->fX = SkScalarToGrScalar(dst.fX);
        dstPoint->fY = SkScalarToGrScalar(dst.fY);
#endif
    }
private:
    const SkRect&   fRect;
    const SkMatrix& fMatrix;
};

#endif

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

void SkGpuDevice::clear(SkColor color) {
    fContext->clear(NULL, color);
}

void SkGpuDevice::drawPaint(const SkDraw& draw, const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    GrPaint grPaint;
    SkAutoCachedTexture act;
    if (!this->skPaint2GrPaintShader(paint,
                                     &act,
                                     *draw.fMatrix,
                                     &grPaint,
                                     true)) {
        return;
    }

    fContext->drawPaint(grPaint);
}

// must be in SkCanvas::PointMode order
static const GrPrimitiveType gPointMode2PrimtiveType[] = {
    kPoints_PrimitiveType,
    kLines_PrimitiveType,
    kLineStrip_PrimitiveType
};

void SkGpuDevice::drawPoints(const SkDraw& draw, SkCanvas::PointMode mode,
                             size_t count, const SkPoint pts[], const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    SkScalar width = paint.getStrokeWidth();
    if (width < 0) {
        return;
    }

    // we only handle hairlines here, else we let the SkDraw call our drawPath()
    if (width > 0) {
        draw.drawPoints(mode, count, pts, paint, true);
        return;
    }

    GrPaint grPaint;
    SkAutoCachedTexture act;
    if (!this->skPaint2GrPaintShader(paint,
                                     &act,
                                     *draw.fMatrix,
                                     &grPaint,
                                     true)) {
        return;
    }

#if SK_SCALAR_IS_GR_SCALAR
    fContext->drawVertices(grPaint,
                           gPointMode2PrimtiveType[mode],
                           count,
                           (GrPoint*)pts,
                           NULL,
                           NULL,
                           NULL,
                           0);
#else
    fContext->drawCustomVertices(grPaint,
                                 gPointMode2PrimtiveType[mode],
                                 SkPositionSource(pts, count));
#endif
}

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

void SkGpuDevice::drawRect(const SkDraw& draw, const SkRect& rect,
                          const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    bool doStroke = paint.getStyle() != SkPaint::kFill_Style;
    SkScalar width = paint.getStrokeWidth();

    /*
        We have special code for hairline strokes, miter-strokes, and fills.
        Anything else we just call our path code.
     */
    bool usePath = doStroke && width > 0 &&
                    paint.getStrokeJoin() != SkPaint::kMiter_Join;
    // another reason we might need to call drawPath...
    if (paint.getMaskFilter()) {
        usePath = true;
    }
    // until we aa rotated rects...
    if (!usePath && paint.isAntiAlias() && !draw.fMatrix->rectStaysRect()) {
        usePath = true;
    }
    // until we can both stroke and fill rectangles
    // with large enough miter limit...
    if (paint.getStyle() == SkPaint::kStrokeAndFill_Style) {
        usePath = true;
    }

    if (usePath) {
        SkPath path;
        path.addRect(rect);
        this->drawPath(draw, path, paint, NULL, true);
        return;
    }

    GrPaint grPaint;
    SkAutoCachedTexture act;
    if (!this->skPaint2GrPaintShader(paint,
                                     &act,
                                     *draw.fMatrix,
                                     &grPaint,
                                     true)) {
        return;
    }
    fContext->drawRect(grPaint, rect, doStroke ? width : -1);
}

#include "SkMaskFilter.h"
#include "SkBounder.h"

static GrPathFill skToGrFillType(SkPath::FillType fillType) {
    switch (fillType) {
        case SkPath::kWinding_FillType:
            return kWinding_PathFill;
        case SkPath::kEvenOdd_FillType:
            return kEvenOdd_PathFill;
        case SkPath::kInverseWinding_FillType:
            return kInverseWinding_PathFill;
        case SkPath::kInverseEvenOdd_FillType:
            return kInverseEvenOdd_PathFill;
        default:
            SkDebugf("Unsupported path fill type\n");
            return kHairLine_PathFill;
    }
}

static void buildKernel(float sigma, float* kernel, int kernelWidth) {
    int halfWidth = (kernelWidth - 1) / 2;
    float sum = 0.0f;
    float denom = 1.0f / (2.0f * sigma * sigma);
    for (int i = 0; i < kernelWidth; ++i) {
        float x = static_cast<float>(i - halfWidth);
        // Note that the constant term (1/(sqrt(2*pi*sigma^2)) of the Gaussian
        // is dropped here, since we renormalize the kernel below.
        kernel[i] = sk_float_exp(- x * x * denom);
        sum += kernel[i];
    }
    // Normalize the kernel
    float scale = 1.0f / sum;
    for (int i = 0; i < kernelWidth; ++i)
        kernel[i] *= scale;
}

static void scaleRect(SkRect* rect, float scale) {
    rect->fLeft *= scale;
    rect->fTop *= scale;
    rect->fRight *= scale;
    rect->fBottom *= scale;
}

static bool drawWithGPUMaskFilter(GrContext* context, const SkPath& path,
                                  SkMaskFilter* filter, const SkMatrix& matrix,
                                  const SkRegion& clip, SkBounder* bounder,
                                  GrPaint* grp) {
#ifdef SK_DISABLE_GPU_BLUR
    return false;
#endif
    SkMaskFilter::BlurInfo info;
    SkMaskFilter::BlurType blurType = filter->asABlur(&info);
    if (SkMaskFilter::kNone_BlurType == blurType) {
        return false;
    }
    SkScalar radius = info.fIgnoreTransform ? info.fRadius
                                            : matrix.mapRadius(info.fRadius);
    radius = SkMinScalar(radius, MAX_BLUR_RADIUS);
    float sigma = SkScalarToFloat(radius) * BLUR_SIGMA_SCALE;
    SkRect srcRect = path.getBounds();

    int scaleFactor = 1;

    while (sigma > MAX_BLUR_SIGMA) {
        scaleFactor *= 2;
        sigma *= 0.5f;
    }
    scaleRect(&srcRect, 1.0f / scaleFactor);
    int halfWidth = static_cast<int>(ceilf(sigma * 3.0f));
    int kernelWidth = halfWidth * 2 + 1;

    SkIRect srcIRect;
    srcRect.roundOut(&srcIRect);
    srcRect.set(srcIRect);
    srcRect.inset(-halfWidth, -halfWidth);

    scaleRect(&srcRect, scaleFactor);
    SkRect finalRect = srcRect;

    SkIRect finalIRect;
    finalRect.roundOut(&finalIRect);
    if (clip.quickReject(finalIRect)) {
        return true;
    }
    if (bounder && !bounder->doIRect(finalIRect)) {
        return true;
    }
    GrPoint offset = GrPoint::Make(-srcRect.fLeft, -srcRect.fTop);
    srcRect.offset(-srcRect.fLeft, -srcRect.fTop);
    const GrTextureDesc desc = {
        kRenderTarget_GrTextureFlagBit,
        kNone_GrAALevel,
        srcRect.width(),
        srcRect.height(),
        // We actually only need A8, but it often isn't supported as a
        // render target
        kRGBA_8888_GrPixelConfig
    };

    GrAutoScratchTexture srcEntry(context, desc);
    GrAutoScratchTexture dstEntry(context, desc);
    if (NULL == srcEntry.texture() || NULL == dstEntry.texture()) {
        return false;
    }
    GrTexture* srcTexture = srcEntry.texture();
    GrTexture* dstTexture = dstEntry.texture();
    if (NULL == srcTexture || NULL == dstTexture) {
        return false;
    }
    GrRenderTarget* oldRenderTarget = context->getRenderTarget();
    // Once this code moves into GrContext, this should be changed to use
    // an AutoClipRestore.
    GrClip oldClip = context->getClip();
    context->setRenderTarget(dstTexture->asRenderTarget());
    context->setClip(srcRect);
    context->clear(NULL, 0);
    GrPaint tempPaint;
    tempPaint.reset();

    GrAutoMatrix avm(context, GrMatrix::I());
    tempPaint.fAntiAlias = grp->fAntiAlias;
    if (tempPaint.fAntiAlias) {
        // AA uses the "coverage" stages on GrDrawTarget. Coverage with a dst
        // blend coeff of zero requires dual source blending support in order
        // to properly blend partially covered pixels. This means the AA
        // code path may not be taken. So we use a dst blend coeff of ISA. We
        // could special case AA draws to a dst surface with known alpha=0 to
        // use a zero dst coeff when dual source blending isn't available.
        tempPaint.fSrcBlendCoeff = kOne_BlendCoeff;
        tempPaint.fDstBlendCoeff = kISC_BlendCoeff;
    }
    // Draw hard shadow to dstTexture with path topleft at origin 0,0.
    context->drawPath(tempPaint, path, skToGrFillType(path.getFillType()), &offset);
    SkTSwap(srcTexture, dstTexture);

    GrMatrix sampleM;
    sampleM.setIDiv(srcTexture->width(), srcTexture->height());
    GrPaint paint;
    paint.reset();
    paint.getTextureSampler(0)->setFilter(GrSamplerState::kBilinear_Filter);
    paint.getTextureSampler(0)->setMatrix(sampleM);
    GrAutoScratchTexture origEntry;

    if (blurType != SkMaskFilter::kNormal_BlurType) {
        // Stash away a copy of the unblurred image.
        origEntry.set(context, desc);
        if (NULL == origEntry.texture()) {
            return false;
        }
        context->setRenderTarget(origEntry.texture()->asRenderTarget());
        paint.setTexture(0, srcTexture);
        context->drawRect(paint, srcRect);
    }
    for (int i = 1; i < scaleFactor; i *= 2) {
        sampleM.setIDiv(srcTexture->width(), srcTexture->height());
        paint.getTextureSampler(0)->setMatrix(sampleM);
        context->setRenderTarget(dstTexture->asRenderTarget());
        SkRect dstRect(srcRect);
        scaleRect(&dstRect, 0.5f);
        paint.setTexture(0, srcTexture);
        context->drawRectToRect(paint, dstRect, srcRect);
        srcRect = dstRect;
        SkTSwap(srcTexture, dstTexture);
    }

    SkAutoTMalloc<float> kernelStorage(kernelWidth);
    float* kernel = kernelStorage.get();
    buildKernel(sigma, kernel, kernelWidth);

    // Clear out a halfWidth to the right of the srcRect to prevent the
    // X convolution from reading garbage.
    SkIRect clearRect = SkIRect::MakeXYWH(
        srcRect.fRight, srcRect.fTop, halfWidth, srcRect.height());
    context->clear(&clearRect, 0x0);

    context->setRenderTarget(dstTexture->asRenderTarget());
    context->convolveInX(srcTexture, srcRect, kernel, kernelWidth);
    SkTSwap(srcTexture, dstTexture);

    // Clear out a halfWidth below the srcRect to prevent the Y
    // convolution from reading garbage.
    clearRect = SkIRect::MakeXYWH(
        srcRect.fLeft, srcRect.fBottom, srcRect.width(), halfWidth);
    context->clear(&clearRect, 0x0);

    context->setRenderTarget(dstTexture->asRenderTarget());
    context->convolveInY(srcTexture, srcRect, kernel, kernelWidth);
    SkTSwap(srcTexture, dstTexture);

    // Clear one pixel to the right and below, to accommodate bilinear
    // upsampling.
    clearRect = SkIRect::MakeXYWH(
        srcRect.fLeft, srcRect.fBottom, srcRect.width() + 1, 1);
    context->clear(&clearRect, 0x0);
    clearRect = SkIRect::MakeXYWH(
        srcRect.fRight, srcRect.fTop, 1, srcRect.height());
    context->clear(&clearRect, 0x0);

    if (scaleFactor > 1) {
        // FIXME:  This should be mitchell, not bilinear.
        paint.getTextureSampler(0)->setFilter(GrSamplerState::kBilinear_Filter);
        sampleM.setIDiv(srcTexture->width(), srcTexture->height());
        paint.getTextureSampler(0)->setMatrix(sampleM);
        context->setRenderTarget(dstTexture->asRenderTarget());
        paint.setTexture(0, srcTexture);
        SkRect dstRect(srcRect);
        scaleRect(&dstRect, scaleFactor);
        context->drawRectToRect(paint, dstRect, srcRect);
        srcRect = dstRect;
        SkTSwap(srcTexture, dstTexture);
    }

    if (blurType != SkMaskFilter::kNormal_BlurType) {
        GrTexture* origTexture = origEntry.texture();
        paint.getTextureSampler(0)->setFilter(GrSamplerState::kNearest_Filter);
        sampleM.setIDiv(origTexture->width(), origTexture->height());
        paint.getTextureSampler(0)->setMatrix(sampleM);
        // Blend origTexture over srcTexture.
        context->setRenderTarget(srcTexture->asRenderTarget());
        paint.setTexture(0, origTexture);
        if (SkMaskFilter::kInner_BlurType == blurType) {
            // inner:  dst = dst * src
            paint.fSrcBlendCoeff = kDC_BlendCoeff;
            paint.fDstBlendCoeff = kZero_BlendCoeff;
        } else if (SkMaskFilter::kSolid_BlurType == blurType) {
            // solid:  dst = src + dst - src * dst
            //             = (1 - dst) * src + 1 * dst
            paint.fSrcBlendCoeff = kIDC_BlendCoeff;
            paint.fDstBlendCoeff = kOne_BlendCoeff;
        } else if (SkMaskFilter::kOuter_BlurType == blurType) {
            // outer:  dst = dst * (1 - src)
            //             = 0 * src + (1 - src) * dst
            paint.fSrcBlendCoeff = kZero_BlendCoeff;
            paint.fDstBlendCoeff = kISC_BlendCoeff;
        }
        context->drawRect(paint, srcRect);
    }
    context->setRenderTarget(oldRenderTarget);
    context->setClip(oldClip);
    
    if (grp->hasTextureOrMask()) {
        GrMatrix inverse;
        if (!matrix.invert(&inverse)) {
            return false;
        }
        grp->preConcatActiveSamplerMatrices(inverse);
    }

    static const int MASK_IDX = GrPaint::kMaxMasks - 1;
    // we assume the last mask index is available for use
    GrAssert(NULL == grp->getMask(MASK_IDX));
    grp->setMask(MASK_IDX, srcTexture);
    grp->getMaskSampler(MASK_IDX)->setClampNoFilter();

    GrMatrix m;
    m.setTranslate(-finalRect.fLeft, -finalRect.fTop);
    m.postIDiv(srcTexture->width(), srcTexture->height());
    grp->getMaskSampler(MASK_IDX)->setMatrix(m);
    context->drawRect(*grp, finalRect);
    return true;
}

static bool drawWithMaskFilter(GrContext* context, const SkPath& path,
                               SkMaskFilter* filter, const SkMatrix& matrix,
                               const SkRegion& clip, SkBounder* bounder,
                               GrPaint* grp) {
    SkMask  srcM, dstM;

    if (!SkDraw::DrawToMask(path, &clip.getBounds(), filter, &matrix, &srcM,
                            SkMask::kComputeBoundsAndRenderImage_CreateMode)) {
        return false;
    }

    SkAutoMaskImage autoSrc(&srcM, false);

    if (!filter->filterMask(&dstM, srcM, matrix, NULL)) {
        return false;
    }
    // this will free-up dstM when we're done (allocated in filterMask())
    SkAutoMaskImage autoDst(&dstM, false);

    if (clip.quickReject(dstM.fBounds)) {
        return false;
    }
    if (bounder && !bounder->doIRect(dstM.fBounds)) {
        return false;
    }

    // we now have a device-aligned 8bit mask in dstM, ready to be drawn using
    // the current clip (and identity matrix) and grpaint settings

    // used to compute inverse view, if necessary
    GrMatrix ivm = context->getMatrix();

    GrAutoMatrix avm(context, GrMatrix::I());

    const GrTextureDesc desc = {
        kNone_GrTextureFlags,
        kNone_GrAALevel,
        dstM.fBounds.width(),
        dstM.fBounds.height(),
        kAlpha_8_GrPixelConfig
    };

    GrAutoScratchTexture ast(context, desc);
    GrTexture* texture = ast.texture();

    if (NULL == texture) {
        return false;
    }
    texture->uploadTextureData(0, 0, desc.fWidth, desc.fHeight, 
                               dstM.fImage, dstM.fRowBytes);

    if (grp->hasTextureOrMask() && ivm.invert(&ivm)) {
        grp->preConcatActiveSamplerMatrices(ivm);
    }

    static const int MASK_IDX = GrPaint::kMaxMasks - 1;
    // we assume the last mask index is available for use
    GrAssert(NULL == grp->getMask(MASK_IDX));
    grp->setMask(MASK_IDX, texture);
    grp->getMaskSampler(MASK_IDX)->setClampNoFilter();

    GrRect d;
    d.setLTRB(GrIntToScalar(dstM.fBounds.fLeft),
              GrIntToScalar(dstM.fBounds.fTop),
              GrIntToScalar(dstM.fBounds.fRight),
              GrIntToScalar(dstM.fBounds.fBottom));

    GrMatrix m;
    m.setTranslate(-dstM.fBounds.fLeft, -dstM.fBounds.fTop);
    m.postIDiv(texture->width(), texture->height());
    grp->getMaskSampler(MASK_IDX)->setMatrix(m);
    
    context->drawRect(*grp, d);
    return true;
}

void SkGpuDevice::drawPath(const SkDraw& draw, const SkPath& origSrcPath,
                           const SkPaint& paint, const SkMatrix* prePathMatrix,
                           bool pathIsMutable) {
    CHECK_SHOULD_DRAW(draw);

    GrPaint grPaint;
    SkAutoCachedTexture act;
    if (!this->skPaint2GrPaintShader(paint,
                                     &act,
                                     *draw.fMatrix,
                                     &grPaint,
                                     true)) {
        return;
    }

    // BEGIN lift from SkDraw::drawPath()

    SkPath*         pathPtr = const_cast<SkPath*>(&origSrcPath);
    bool            doFill = true;
    SkPath          tmpPath;

    if (prePathMatrix) {
        SkPath* result = pathPtr;

        if (!pathIsMutable) {
            result = &tmpPath;
            pathIsMutable = true;
        }
        // should I push prePathMatrix on our MV stack temporarily, instead
        // of applying it here? See SkDraw.cpp
        pathPtr->transform(*prePathMatrix, result);
        pathPtr = result;
    }
    // at this point we're done with prePathMatrix
    SkDEBUGCODE(prePathMatrix = (const SkMatrix*)0x50FF8001;)

    // This "if" is not part of the SkDraw::drawPath() lift.
    // When we get a 1.0 wide stroke we hairline stroke it instead of creating
    // a new stroked-path. This is motivated by canvas2D sites that draw
    // lines as 1.0 wide stroked paths. We can consider doing an alpha-modulated-
    // hairline for width < 1.0 when AA is enabled.
    static const int gMatrixMask = ~(SkMatrix::kIdentity_Mask | 
                                     SkMatrix::kTranslate_Mask);
    if (!paint.getPathEffect() && 
        SkPaint::kStroke_Style == paint.getStyle() &&
        !(draw.fMatrix->getType() & gMatrixMask) &&
        SK_Scalar1 == paint.getStrokeWidth()) {
        doFill = false;
    }

    if (doFill && (paint.getPathEffect() || 
                   paint.getStyle() != SkPaint::kFill_Style)) {
        doFill = paint.getFillPath(*pathPtr, &tmpPath);
        pathPtr = &tmpPath;
    }

    // END lift from SkDraw::drawPath()

    if (paint.getMaskFilter()) {
        // avoid possibly allocating a new path in transform if we can
        SkPath* devPathPtr = pathIsMutable ? pathPtr : &tmpPath;

        // transform the path into device space
        pathPtr->transform(*draw.fMatrix, devPathPtr);
        if (!drawWithGPUMaskFilter(fContext, *devPathPtr, paint.getMaskFilter(),
                                   *draw.fMatrix, *draw.fClip, draw.fBounder,
                                   &grPaint)) {
            drawWithMaskFilter(fContext, *devPathPtr, paint.getMaskFilter(),
                               *draw.fMatrix, *draw.fClip, draw.fBounder,
                               &grPaint);
        }
        return;
    }

    GrPathFill fill = kHairLine_PathFill;

    if (doFill) {
        switch (pathPtr->getFillType()) {
            case SkPath::kWinding_FillType:
                fill = kWinding_PathFill;
                break;
            case SkPath::kEvenOdd_FillType:
                fill = kEvenOdd_PathFill;
                break;
            case SkPath::kInverseWinding_FillType:
                fill = kInverseWinding_PathFill;
                break;
            case SkPath::kInverseEvenOdd_FillType:
                fill = kInverseEvenOdd_PathFill;
                break;
            default:
                SkDebugf("Unsupported path fill type\n");
                return;
        }
    }

    fContext->drawPath(grPaint, *pathPtr, fill);
}

void SkGpuDevice::drawBitmap(const SkDraw& draw,
                             const SkBitmap& bitmap,
                             const SkIRect* srcRectPtr,
                             const SkMatrix& m,
                             const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    SkIRect srcRect;
    if (NULL == srcRectPtr) {
        srcRect.set(0, 0, bitmap.width(), bitmap.height());
    } else {
        srcRect = *srcRectPtr;
    }

    if (paint.getMaskFilter()){
        SkBitmap        tmp;    // storage if we need a subset of bitmap
        const SkBitmap* bitmapPtr = &bitmap;
        if (srcRectPtr) {
            if (!bitmap.extractSubset(&tmp, srcRect)) {
                return;     // extraction failed
            }
            bitmapPtr = &tmp;
        }
        SkPaint paintWithTexture(paint);
        paintWithTexture.setShader(SkShader::CreateBitmapShader( *bitmapPtr,
            SkShader::kClamp_TileMode, SkShader::kClamp_TileMode))->unref();
        paintWithTexture.getShader()->setLocalMatrix(m);

        SkRect ScalarRect;
        ScalarRect.set(srcRect);

        if (m.rectStaysRect()) {
            // Preferred drawing method, optimized for rectangles
            m.mapRect(&ScalarRect);
            this->drawRect(draw, ScalarRect, paintWithTexture);
        } else {
            // Slower drawing method, for warped or rotated rectangles
            SkPath path;
            path.addRect(ScalarRect);
            path.transform(m);
            this->drawPath(draw, path, paintWithTexture, NULL, true);
        }
        return;
    }

    GrPaint grPaint;
    if (!this->skPaint2GrPaintNoShader(paint, true, &grPaint, false)) {
        return;
    }
    GrSamplerState* sampler = grPaint.getTextureSampler(kBitmapTextureIdx);
    if (paint.isFilterBitmap()) {
        sampler->setFilter(GrSamplerState::kBilinear_Filter);
    } else {
        sampler->setFilter(GrSamplerState::kNearest_Filter);
    }

    const int maxTextureSize = fContext->getMaxTextureSize();
    if (bitmap.getTexture() || (bitmap.width() <= maxTextureSize &&
                                bitmap.height() <= maxTextureSize)) {
        // take the fast case
        this->internalDrawBitmap(draw, bitmap, srcRect, m, &grPaint);
        return;
    }

    // undo the translate done by SkCanvas
    int DX = SkMax32(0, srcRect.fLeft);
    int DY = SkMax32(0, srcRect.fTop);
    // compute clip bounds in local coordinates
    SkIRect clipRect;
    {
        SkRect r;
        r.set(draw.fClip->getBounds());
        SkMatrix matrix, inverse;
        matrix.setConcat(*draw.fMatrix, m);
        if (!matrix.invert(&inverse)) {
            return;
        }
        inverse.mapRect(&r);
        r.roundOut(&clipRect);
        // apply the canvas' translate to our local clip
        clipRect.offset(DX, DY);
    }

    int nx = bitmap.width() / maxTextureSize;
    int ny = bitmap.height() / maxTextureSize;
    for (int x = 0; x <= nx; x++) {
        for (int y = 0; y <= ny; y++) {
            SkIRect tileR;
            tileR.set(x * maxTextureSize, y * maxTextureSize,
                      (x + 1) * maxTextureSize, (y + 1) * maxTextureSize);
            if (!SkIRect::Intersects(tileR, clipRect)) {
                continue;
            }

            SkIRect srcR = tileR;
            if (!srcR.intersect(srcRect)) {
                continue;
            }

            SkBitmap tmpB;
            if (bitmap.extractSubset(&tmpB, tileR)) {
                // now offset it to make it "local" to our tmp bitmap
                srcR.offset(-tileR.fLeft, -tileR.fTop);

                SkMatrix tmpM(m);
                {
                    int dx = tileR.fLeft - DX + SkMax32(0, srcR.fLeft);
                    int dy = tileR.fTop -  DY + SkMax32(0, srcR.fTop);
                    tmpM.preTranslate(SkIntToScalar(dx), SkIntToScalar(dy));
                }
                this->internalDrawBitmap(draw, tmpB, srcR, tmpM, &grPaint);
            }
        }
    }
}

/*
 *  This is called by drawBitmap(), which has to handle images that may be too
 *  large to be represented by a single texture.
 *
 *  internalDrawBitmap assumes that the specified bitmap will fit in a texture
 *  and that non-texture portion of the GrPaint has already been setup.
 */
void SkGpuDevice::internalDrawBitmap(const SkDraw& draw,
                                     const SkBitmap& bitmap,
                                     const SkIRect& srcRect,
                                     const SkMatrix& m,
                                     GrPaint* grPaint) {
    SkASSERT(bitmap.width() <= fContext->getMaxTextureSize() &&
             bitmap.height() <= fContext->getMaxTextureSize());

    SkAutoLockPixels alp(bitmap, !bitmap.getTexture());
    if (!bitmap.getTexture() && !bitmap.readyToDraw()) {
        SkDebugf("nothing to draw\n");
        return;
    }

    GrSamplerState* sampler = grPaint->getTextureSampler(kBitmapTextureIdx);

    sampler->setWrapX(GrSamplerState::kClamp_WrapMode);
    sampler->setWrapY(GrSamplerState::kClamp_WrapMode);
    sampler->setSampleMode(GrSamplerState::kNormal_SampleMode);
    sampler->setMatrix(GrMatrix::I());

    GrTexture* texture;
    SkAutoCachedTexture act(this, bitmap, *sampler, &texture);
    if (NULL == texture) {
        return;
    }

    grPaint->setTexture(kShaderTextureIdx, texture);

    GrRect dstRect = SkRect::MakeWH(GrIntToScalar(srcRect.width()),
                                    GrIntToScalar(srcRect.height()));
    GrRect paintRect;
    paintRect.setLTRB(GrFixedToScalar((srcRect.fLeft << 16) / bitmap.width()),
                      GrFixedToScalar((srcRect.fTop << 16) / bitmap.height()),
                      GrFixedToScalar((srcRect.fRight << 16) / bitmap.width()),
                      GrFixedToScalar((srcRect.fBottom << 16) / bitmap.height()));

    if (GrSamplerState::kNearest_Filter != sampler->getFilter() &&
        (srcRect.width() < bitmap.width() || 
         srcRect.height() < bitmap.height())) {
        // If drawing a subrect of the bitmap and filtering is enabled,
        // use a constrained texture domain to avoid color bleeding
        GrScalar left, top, right, bottom;
        if (srcRect.width() > 1) {
            GrScalar border = GR_ScalarHalf / bitmap.width();
            left = paintRect.left() + border;
            right = paintRect.right() - border;
        } else {
            left = right = GrScalarHalf(paintRect.left() + paintRect.right());
        }
        if (srcRect.height() > 1) {
            GrScalar border = GR_ScalarHalf / bitmap.height();
            top = paintRect.top() + border;
            bottom = paintRect.bottom() - border;
        } else {
            top = bottom = GrScalarHalf(paintRect.top() + paintRect.bottom());
        }
        GrRect textureDomain;
        textureDomain.setLTRB(left, top, right, bottom);
        sampler->setTextureDomain(textureDomain);
    }

    fContext->drawRectToRect(*grPaint, dstRect, paintRect, &m);
}

void SkGpuDevice::drawSprite(const SkDraw& draw, const SkBitmap& bitmap,
                            int left, int top, const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    SkAutoLockPixels alp(bitmap);
    if (!bitmap.getTexture() && !bitmap.readyToDraw()) {
        return;
    }

    GrPaint grPaint;
    if(!this->skPaint2GrPaintNoShader(paint, true, &grPaint, false)) {
        return;
    }

    GrAutoMatrix avm(fContext, GrMatrix::I());

    GrSamplerState* sampler = grPaint.getTextureSampler(kBitmapTextureIdx);

    GrTexture* texture;
    sampler->setClampNoFilter();
    SkAutoCachedTexture act(this, bitmap, *sampler, &texture);

    grPaint.setTexture(kBitmapTextureIdx, texture);

    fContext->drawRectToRect(grPaint,
                             GrRect::MakeXYWH(GrIntToScalar(left),
                                              GrIntToScalar(top),
                                              GrIntToScalar(bitmap.width()),
                                              GrIntToScalar(bitmap.height())),
                             GrRect::MakeWH(GR_Scalar1, GR_Scalar1));
}

void SkGpuDevice::drawDevice(const SkDraw& draw, SkDevice* dev,
                            int x, int y, const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    GrPaint grPaint;
    if (!((SkGpuDevice*)dev)->bindDeviceAsTexture(&grPaint) ||
        !this->skPaint2GrPaintNoShader(paint, true, &grPaint, false)) {
        return;
    }

    GrTexture* devTex = grPaint.getTexture(0);
    SkASSERT(NULL != devTex);

    const SkBitmap& bm = dev->accessBitmap(false);
    int w = bm.width();
    int h = bm.height();

    GrAutoMatrix avm(fContext, GrMatrix::I());

    grPaint.getTextureSampler(kBitmapTextureIdx)->setClampNoFilter();

    GrRect dstRect = GrRect::MakeXYWH(GrIntToScalar(x),
                                      GrIntToScalar(y),
                                      GrIntToScalar(w),
                                      GrIntToScalar(h));
    // The device being drawn may not fill up its texture (saveLayer uses
    // the approximate ).
    GrRect srcRect = GrRect::MakeWH(GR_Scalar1 * w / devTex->width(),
                                    GR_Scalar1 * h / devTex->height());

    fContext->drawRectToRect(grPaint, dstRect, srcRect);
}

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

// must be in SkCanvas::VertexMode order
static const GrPrimitiveType gVertexMode2PrimitiveType[] = {
    kTriangles_PrimitiveType,
    kTriangleStrip_PrimitiveType,
    kTriangleFan_PrimitiveType,
};

void SkGpuDevice::drawVertices(const SkDraw& draw, SkCanvas::VertexMode vmode,
                              int vertexCount, const SkPoint vertices[],
                              const SkPoint texs[], const SkColor colors[],
                              SkXfermode* xmode,
                              const uint16_t indices[], int indexCount,
                              const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    GrPaint grPaint;
    SkAutoCachedTexture act;
    // we ignore the shader if texs is null.
    if (NULL == texs) {
        if (!this->skPaint2GrPaintNoShader(paint,
                                           false,
                                           &grPaint, 
                                           NULL == colors)) {
            return;
        }
    } else {
        if (!this->skPaint2GrPaintShader(paint, &act,
                                         *draw.fMatrix,
                                         &grPaint,
                                         NULL == colors)) {
            return;
        }
    }

    if (NULL != xmode && NULL != texs && NULL != colors) {
        SkXfermode::Mode mode;
        if (!SkXfermode::IsMode(xmode, &mode) ||
            SkXfermode::kMultiply_Mode != mode) {
            SkDebugf("Unsupported vertex-color/texture xfer mode.\n");
#if 0
            return
#endif
        }
    }

#if SK_SCALAR_IS_GR_SCALAR
    // even if GrColor and SkColor byte offsets match we need
    // to perform pre-multiply.
    if (NULL == colors) {
        fContext->drawVertices(grPaint,
                               gVertexMode2PrimitiveType[vmode],
                               vertexCount,
                               (GrPoint*) vertices,
                               (GrPoint*) texs,
                               NULL,
                               indices,
                               indexCount);
    } else
#endif
    {
        SkTexCoordSource texSrc(texs);
        SkColorSource colSrc(colors);
        SkIndexSource idxSrc(indices, indexCount);

        fContext->drawCustomVertices(grPaint,
                                     gVertexMode2PrimitiveType[vmode],
                                     SkPositionSource(vertices, vertexCount),
                                     (NULL == texs) ? NULL : &texSrc,
                                     (NULL == colors) ? NULL : &colSrc,
                                     (NULL == indices) ? NULL : &idxSrc);
    }
}

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

static void GlyphCacheAuxProc(void* data) {
    delete (GrFontScaler*)data;
}

static GrFontScaler* get_gr_font_scaler(SkGlyphCache* cache) {
    void* auxData;
    GrFontScaler* scaler = NULL;
    if (cache->getAuxProcData(GlyphCacheAuxProc, &auxData)) {
        scaler = (GrFontScaler*)auxData;
    }
    if (NULL == scaler) {
        scaler = new SkGrFontScaler(cache);
        cache->setAuxProc(GlyphCacheAuxProc, scaler);
    }
    return scaler;
}

static void SkGPU_Draw1Glyph(const SkDraw1Glyph& state,
                             SkFixed fx, SkFixed fy,
                             const SkGlyph& glyph) {
    SkASSERT(glyph.fWidth > 0 && glyph.fHeight > 0);

    GrSkDrawProcs* procs = (GrSkDrawProcs*)state.fDraw->fProcs;

    if (NULL == procs->fFontScaler) {
        procs->fFontScaler = get_gr_font_scaler(state.fCache);
    }

    /*
     *  What should we do with fy? (assuming horizontal/latin text)
     *
     *  The raster code calls SkFixedFloorToFixed on it, as it does with fx.
     *  It calls that rather than round, because our caller has already added
     *  SK_FixedHalf, so that calling floor gives us the rounded integer.
     *
     *  Test code between raster and gpu (they should draw the same)
     *
     *      canvas->drawText("Hamburgefons", 12, 0, 16.5f, paint);
     *
     *  Perhaps we should only perform this integralization if there is no
     *  fExtMatrix...
     */
    fy = SkFixedFloorToFixed(fy);

    procs->fTextContext->drawPackedGlyph(GrGlyph::Pack(glyph.getGlyphID(), fx, 0),
                                         SkFixedFloorToFixed(fx), fy,
                                         procs->fFontScaler);
}

SkDrawProcs* SkGpuDevice::initDrawForText(GrTextContext* context) {

    // deferred allocation
    if (NULL == fDrawProcs) {
        fDrawProcs = new GrSkDrawProcs;
        fDrawProcs->fD1GProc = SkGPU_Draw1Glyph;
        fDrawProcs->fContext = fContext;
    }

    // init our (and GL's) state
    fDrawProcs->fTextContext = context;
    fDrawProcs->fFontScaler = NULL;
    return fDrawProcs;
}

void SkGpuDevice::drawText(const SkDraw& draw, const void* text,
                          size_t byteLength, SkScalar x, SkScalar y,
                          const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    if (draw.fMatrix->getType() & SkMatrix::kPerspective_Mask) {
        // this guy will just call our drawPath()
        draw.drawText((const char*)text, byteLength, x, y, paint);
    } else {
        SkDraw myDraw(draw);

        GrPaint grPaint;
        SkAutoCachedTexture act;

        if (!this->skPaint2GrPaintShader(paint,
                                         &act,
                                         *draw.fMatrix,
                                         &grPaint,
                                         true)) {
            return;
        }
        GrTextContext context(fContext, grPaint, draw.fExtMatrix);
        myDraw.fProcs = this->initDrawForText(&context);
        this->INHERITED::drawText(myDraw, text, byteLength, x, y, paint);
    }
}

void SkGpuDevice::drawPosText(const SkDraw& draw, const void* text,
                             size_t byteLength, const SkScalar pos[],
                             SkScalar constY, int scalarsPerPos,
                             const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    if (draw.fMatrix->getType() & SkMatrix::kPerspective_Mask) {
        // this guy will just call our drawPath()
        draw.drawPosText((const char*)text, byteLength, pos, constY,
                         scalarsPerPos, paint);
    } else {
        SkDraw myDraw(draw);

        GrPaint grPaint;
        SkAutoCachedTexture act;
        if (!this->skPaint2GrPaintShader(paint,
                                         &act,
                                         *draw.fMatrix,
                                         &grPaint,
                                         true)) {
            return;
        }

        GrTextContext context(fContext, grPaint, draw.fExtMatrix);
        myDraw.fProcs = this->initDrawForText(&context);
        this->INHERITED::drawPosText(myDraw, text, byteLength, pos, constY,
                                     scalarsPerPos, paint);
    }
}

void SkGpuDevice::drawTextOnPath(const SkDraw& draw, const void* text,
                                size_t len, const SkPath& path,
                                const SkMatrix* m, const SkPaint& paint) {
    CHECK_SHOULD_DRAW(draw);

    SkASSERT(draw.fDevice == this);
    draw.drawTextOnPath((const char*)text, len, path, m, paint);
}

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

bool SkGpuDevice::filterTextFlags(const SkPaint& paint, TextFlags* flags) {
    if (!paint.isLCDRenderText()) {
        // we're cool with the paint as is
        return false;
    }

    if (paint.getShader() ||
        paint.getXfermode() || // unless its srcover
        paint.getMaskFilter() ||
        paint.getRasterizer() ||
        paint.getColorFilter() ||
        paint.getPathEffect() ||
        paint.isFakeBoldText() ||
        paint.getStyle() != SkPaint::kFill_Style) {
        // turn off lcd
        flags->fFlags = paint.getFlags() & ~SkPaint::kLCDRenderText_Flag;
        flags->fHinting = paint.getHinting();
        return true;
    }
    // we're cool with the paint as is
    return false;
}

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

SkGpuDevice::TexCache SkGpuDevice::lockCachedTexture(const SkBitmap& bitmap,
                                            const GrSamplerState& sampler,
                                            TexType type) {
    GrContext::TextureCacheEntry entry;
    GrContext* ctx = this->context();

    if (kBitmap_TexType != type) {
        const GrTextureDesc desc = {
            kRenderTarget_GrTextureFlagBit,
            kNone_GrAALevel,
            bitmap.width(),
            bitmap.height(),
            SkGr::Bitmap2PixelConfig(bitmap)
        };
        GrContext::ScratchTexMatch match;
        if (kSaveLayerDeviceRenderTarget_TexType == type) {
            // we know layers will only be drawn through drawDevice.
            // drawDevice has been made to work with content embedded in a
            // larger texture so its okay to use the approximate version.
            match = GrContext::kApprox_ScratchTexMatch;
        } else {
            SkASSERT(kDeviceRenderTarget_TexType == type);
            match = GrContext::kExact_ScratchTexMatch;
        }
        entry = ctx->lockScratchTexture(desc, match);
    } else {
        if (!bitmap.isVolatile()) {
            GrContext::TextureKey key = bitmap.getGenerationID();
            key |= ((uint64_t) bitmap.pixelRefOffset()) << 32;
        
            entry = ctx->findAndLockTexture(key, bitmap.width(),
                                            bitmap.height(), sampler);
            if (NULL == entry.texture()) {
                entry = sk_gr_create_bitmap_texture(ctx, key, sampler, 
                                                    bitmap);
            }
        } else {
            entry = sk_gr_create_bitmap_texture(ctx, gUNCACHED_KEY, sampler, bitmap);
        }
        if (NULL == entry.texture()) {
            GrPrintf("---- failed to create texture for cache [%d %d]\n",
                     bitmap.width(), bitmap.height());
        }
    }
    return entry;
}

void SkGpuDevice::unlockCachedTexture(TexCache cache) {
    this->context()->unlockTexture(cache);
}

SkDevice* SkGpuDevice::onCreateCompatibleDevice(SkBitmap::Config config, 
                                                int width, int height, 
                                                bool isOpaque,
                                                Usage usage) {
    return SkNEW_ARGS(SkGpuDevice,(this->context(), config, 
                                   width, height, usage));
}