gpu/src/GrContext.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 "GrBufferAllocPool.h"
#include "GrClipIterator.h"
#include "GrContext.h"
#include "GrGpu.h"
#include "GrIndexBuffer.h"
#include "GrInOrderDrawBuffer.h"
#include "GrPathRenderer.h"
#include "GrPathUtils.h"
#include "GrTextureCache.h"
#include "GrTextStrike.h"
#include "SkTrace.h"

// Using MSAA seems to be slower for some yet unknown reason.
#define PREFER_MSAA_OFFSCREEN_AA 0
#define OFFSCREEN_SSAA_SCALE 4 // super sample at 4x4

#define DEFER_TEXT_RENDERING 1

#define BATCH_RECT_TO_RECT (1 && !GR_STATIC_RECT_VB)

static const size_t MAX_TEXTURE_CACHE_COUNT = 128;
static const size_t MAX_TEXTURE_CACHE_BYTES = 8 * 1024 * 1024;

static const size_t DRAW_BUFFER_VBPOOL_BUFFER_SIZE = 1 << 18;
static const int DRAW_BUFFER_VBPOOL_PREALLOC_BUFFERS = 4;

// We are currently only batching Text and drawRectToRect, both
// of which use the quad index buffer.
static const size_t DRAW_BUFFER_IBPOOL_BUFFER_SIZE = 0;
static const int DRAW_BUFFER_IBPOOL_PREALLOC_BUFFERS = 0;

GrContext* GrContext::Create(GrEngine engine,
                             GrPlatform3DContext context3D) {
    GrContext* ctx = NULL;
    GrGpu* fGpu = GrGpu::Create(engine, context3D);
    if (NULL != fGpu) {
        ctx = new GrContext(fGpu);
        fGpu->unref();
    }
    return ctx;
}

GrContext* GrContext::CreateGLShaderContext() {
    return GrContext::Create(kOpenGL_Shaders_GrEngine, 0);
}

GrContext::~GrContext() {
    this->flush();
    delete fTextureCache;
    delete fFontCache;
    delete fDrawBuffer;
    delete fDrawBufferVBAllocPool;
    delete fDrawBufferIBAllocPool;
    GrSafeUnref(fCustomPathRenderer);
    GrSafeUnref(fAAFillRectIndexBuffer);
    GrSafeUnref(fAAStrokeRectIndexBuffer);
    fGpu->unref();
}

void GrContext::contextLost() {
    contextDestroyed();
    this->setupDrawBuffer();
}

void GrContext::contextDestroyed() {
    // abandon first to so destructors
    // don't try to free the resources in the API.
    fGpu->abandonResources();

    delete fDrawBuffer;
    fDrawBuffer = NULL;

    delete fDrawBufferVBAllocPool;
    fDrawBufferVBAllocPool = NULL;

    delete fDrawBufferIBAllocPool;
    fDrawBufferIBAllocPool = NULL;

    GrSafeSetNull(fAAFillRectIndexBuffer);
    GrSafeSetNull(fAAStrokeRectIndexBuffer);

    fTextureCache->removeAll();
    fFontCache->freeAll();
    fGpu->markContextDirty();
}

void GrContext::resetContext() {
    fGpu->markContextDirty();
}

void GrContext::freeGpuResources() {
    this->flush();
    fTextureCache->removeAll();
    fFontCache->freeAll();
}

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

int GrContext::PaintStageVertexLayoutBits(
                            const GrPaint& paint,
                            const bool hasTexCoords[GrPaint::kTotalStages]) {
    int stageMask = paint.getActiveStageMask();
    int layout = 0;
    for (int i = 0; i < GrPaint::kTotalStages; ++i) {
        if ((1 << i) & stageMask) {
            if (NULL != hasTexCoords && hasTexCoords[i]) {
                layout |= GrDrawTarget::StageTexCoordVertexLayoutBit(i, i);
            } else {
                layout |= GrDrawTarget::StagePosAsTexCoordVertexLayoutBit(i);
            }
        }
    }
    return layout;
}


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

enum {
    kNPOTBit    = 0x1,
    kFilterBit  = 0x2,
    kKeylessBit = 0x4,
};

bool GrContext::finalizeTextureKey(GrTextureKey* key,
                                   const GrSamplerState& sampler,
                                   bool keyless) const {
    uint32_t bits = 0;
    uint16_t width = key->width();
    uint16_t height = key->height();

    if (!fGpu->npotTextureTileSupport()) {
        bool isPow2 = GrIsPow2(width) && GrIsPow2(height);

        bool tiled = (sampler.getWrapX() != GrSamplerState::kClamp_WrapMode) ||
                     (sampler.getWrapY() != GrSamplerState::kClamp_WrapMode);

        if (tiled && !isPow2) {
            bits |= kNPOTBit;
            if (GrSamplerState::kNearest_Filter != sampler.getFilter()) {
                bits |= kFilterBit;
            }
        }
    }

    if (keyless) {
        bits |= kKeylessBit;
    }
    key->finalize(bits);
    return 0 != bits;
}

GrTextureEntry* GrContext::findAndLockTexture(GrTextureKey* key,
                                              const GrSamplerState& sampler) {
    finalizeTextureKey(key, sampler, false);
    return fTextureCache->findAndLock(*key);
}

static void stretchImage(void* dst,
                         int dstW,
                         int dstH,
                         void* src,
                         int srcW,
                         int srcH,
                         int bpp) {
    GrFixed dx = (srcW << 16) / dstW;
    GrFixed dy = (srcH << 16) / dstH;

    GrFixed y = dy >> 1;

    int dstXLimit = dstW*bpp;
    for (int j = 0; j < dstH; ++j) {
        GrFixed x = dx >> 1;
        void* srcRow = (uint8_t*)src + (y>>16)*srcW*bpp;
        void* dstRow = (uint8_t*)dst + j*dstW*bpp;
        for (int i = 0; i < dstXLimit; i += bpp) {
            memcpy((uint8_t*) dstRow + i,
                   (uint8_t*) srcRow + (x>>16)*bpp,
                   bpp);
            x += dx;
        }
        y += dy;
    }
}

GrTextureEntry* GrContext::createAndLockTexture(GrTextureKey* key,
                                                const GrSamplerState& sampler,
                                                const GrTextureDesc& desc,
                                                void* srcData, size_t rowBytes) {
    SK_TRACE_EVENT0("GrContext::createAndLockTexture");
    GrAssert(key->width() == desc.fWidth);
    GrAssert(key->height() == desc.fHeight);

#if GR_DUMP_TEXTURE_UPLOAD
    GrPrintf("GrContext::createAndLockTexture [%d %d]\n", desc.fWidth, desc.fHeight);
#endif

    GrTextureEntry* entry = NULL;
    bool special = finalizeTextureKey(key, sampler, false);
    if (special) {
        GrTextureEntry* clampEntry;
        GrTextureKey clampKey(*key);
        clampEntry = findAndLockTexture(&clampKey, GrSamplerState::ClampNoFilter());

        if (NULL == clampEntry) {
            clampEntry = createAndLockTexture(&clampKey,
                                              GrSamplerState::ClampNoFilter(),
                                              desc, srcData, rowBytes);
            GrAssert(NULL != clampEntry);
            if (NULL == clampEntry) {
                return NULL;
            }
        }
        GrTextureDesc rtDesc = desc;
        rtDesc.fFlags =  rtDesc.fFlags |
                         kRenderTarget_GrTextureFlagBit |
                         kNoStencil_GrTextureFlagBit;
        rtDesc.fWidth  = GrNextPow2(GrMax<int>(desc.fWidth,
                                               fGpu->minRenderTargetWidth()));
        rtDesc.fHeight = GrNextPow2(GrMax<int>(desc.fHeight,
                                               fGpu->minRenderTargetHeight()));

        GrTexture* texture = fGpu->createTexture(rtDesc, NULL, 0);

        if (NULL != texture) {
            GrDrawTarget::AutoStateRestore asr(fGpu);
            fGpu->setRenderTarget(texture->asRenderTarget());
            fGpu->setTexture(0, clampEntry->texture());
            fGpu->disableStencil();
            fGpu->setViewMatrix(GrMatrix::I());
            fGpu->setAlpha(0xff);
            fGpu->setBlendFunc(kOne_BlendCoeff, kZero_BlendCoeff);
            fGpu->disableState(GrDrawTarget::kDither_StateBit |
                               GrDrawTarget::kClip_StateBit   |
                               GrDrawTarget::kAntialias_StateBit);
            GrSamplerState::Filter filter;
            // if filtering is not desired then we want to ensure all
            // texels in the resampled image are copies of texels from
            // the original.
            if (GrSamplerState::kNearest_Filter == sampler.getFilter()) {
                filter = GrSamplerState::kNearest_Filter;
            } else {
                filter = GrSamplerState::kBilinear_Filter;
            }
            GrSamplerState stretchSampler(GrSamplerState::kClamp_WrapMode,
                                          GrSamplerState::kClamp_WrapMode,
                                          filter);
            fGpu->setSamplerState(0, stretchSampler);

            static const GrVertexLayout layout =
                                GrDrawTarget::StageTexCoordVertexLayoutBit(0,0);
            GrDrawTarget::AutoReleaseGeometry arg(fGpu, layout, 4, 0);

            if (arg.succeeded()) {
                GrPoint* verts = (GrPoint*) arg.vertices();
                verts[0].setIRectFan(0, 0,
                                     texture->width(),
                                     texture->height(),
                                     2*sizeof(GrPoint));
                verts[1].setIRectFan(0, 0, 1, 1, 2*sizeof(GrPoint));
                fGpu->drawNonIndexed(kTriangleFan_PrimitiveType,
                                     0, 4);
                entry = fTextureCache->createAndLock(*key, texture);
            }
            texture->releaseRenderTarget();
        } else {
            // TODO: Our CPU stretch doesn't filter. But we create separate
            // stretched textures when the sampler state is either filtered or
            // not. Either implement filtered stretch blit on CPU or just create
            // one when FBO case fails.

            rtDesc.fFlags = kNone_GrTextureFlags;
            // no longer need to clamp at min RT size.
            rtDesc.fWidth  = GrNextPow2(desc.fWidth);
            rtDesc.fHeight = GrNextPow2(desc.fHeight);
            int bpp = GrBytesPerPixel(desc.fFormat);
            SkAutoSMalloc<128*128*4> stretchedPixels(bpp *
                                                     rtDesc.fWidth *
                                                     rtDesc.fHeight);
            stretchImage(stretchedPixels.get(), rtDesc.fWidth, rtDesc.fHeight,
                         srcData, desc.fWidth, desc.fHeight, bpp);

            size_t stretchedRowBytes = rtDesc.fWidth * bpp;

            GrTexture* texture = fGpu->createTexture(rtDesc,
                                                     stretchedPixels.get(),
                                                     stretchedRowBytes);
            GrAssert(NULL != texture);
            entry = fTextureCache->createAndLock(*key, texture);
        }
        fTextureCache->unlock(clampEntry);

    } else {
        GrTexture* texture = fGpu->createTexture(desc, srcData, rowBytes);
        if (NULL != texture) {
            entry = fTextureCache->createAndLock(*key, texture);
        } else {
            entry = NULL;
        }
    }
    return entry;
}

GrTextureEntry* GrContext::lockKeylessTexture(const GrTextureDesc& desc) {
    uint32_t p0 = desc.fFormat;
    uint32_t p1 = (desc.fAALevel << 16) | desc.fFlags;
    GrTextureKey key(p0, p1, desc.fWidth, desc.fHeight);
    this->finalizeTextureKey(&key, GrSamplerState::ClampNoFilter(), true);
    
    GrTextureEntry* entry = fTextureCache->findAndLock(key);
    if (NULL == entry) {
        GrTexture* texture = fGpu->createTexture(desc, NULL, 0);
        if (NULL != texture) {
            entry = fTextureCache->createAndLock(key, texture);
        }
    }
    // If the caller gives us the same desc/sampler twice we don't want
    // to return the same texture the second time (unless it was previously
    // released). So we detach the entry from the cache and reattach at release.
    if (NULL != entry) {
        fTextureCache->detach(entry);
    }
    return entry;
}

GrTextureEntry* GrContext::findApproximateKeylessTexture(
                                                    const GrTextureDesc& inDesc) {
    GrTextureDesc desc = inDesc;
    // bin by pow2 with a reasonable min
    static const int MIN_SIZE = 256;
    desc.fWidth  = GrMax(MIN_SIZE, GrNextPow2(desc.fWidth));
    desc.fHeight = GrMax(MIN_SIZE, GrNextPow2(desc.fHeight));

    uint32_t p0 = desc.fFormat;
    uint32_t p1 = (desc.fAALevel << 16) | desc.fFlags;
    
    GrTextureEntry* entry;
    bool keepTrying = true;
    int origWidth = desc.fWidth;
    int origHeight = desc.fHeight;
    bool doubledW = false;
    bool doubledH = false;

    do {
        GrTextureKey key(p0, p1, desc.fWidth, desc.fHeight);
        this->finalizeTextureKey(&key, GrSamplerState::ClampNoFilter(), true);
        entry = fTextureCache->findAndLock(key);

        // if we miss, relax the fit of the flags...
        // then try doubling width... then height.
        if (NULL != entry) {
            break;
        }
        if (!(desc.fFlags & kRenderTarget_GrTextureFlagBit)) {
            desc.fFlags = desc.fFlags | kRenderTarget_GrTextureFlagBit;
        } else if (desc.fFlags & kNoStencil_GrTextureFlagBit) {
            desc.fFlags = desc.fFlags & ~kNoStencil_GrTextureFlagBit;
        } else if (!doubledW) {
            desc.fFlags = inDesc.fFlags;
            desc.fWidth *= 2;
            doubledW = true;
        } else if (!doubledH) {
            desc.fFlags = inDesc.fFlags;
            desc.fWidth = origWidth;
            desc.fHeight *= 2;
            doubledH = true;
        } else {
            break;
        }
        
    } while (true);

    if (NULL == entry) {
        desc.fFlags = inDesc.fFlags;
        desc.fWidth = origWidth;
        desc.fHeight = origHeight;
        GrTexture* texture = fGpu->createTexture(desc, NULL, 0);
        if (NULL != texture) {
            GrTextureKey key(p0, p1, desc.fWidth, desc.fHeight);
            this->finalizeTextureKey(&key, GrSamplerState::ClampNoFilter(), 
                                     true);
            entry = fTextureCache->createAndLock(key, texture);
        }
    }

    // If the caller gives us the same desc/sampler twice we don't want
    // to return the same texture the second time (unless it was previously
    // released). So we detach the entry from the cache and reattach at release.
    if (NULL != entry) {
        fTextureCache->detach(entry);
    }
    return entry;
}

void GrContext::unlockTexture(GrTextureEntry* entry) {
    if (kKeylessBit & entry->key().getPrivateBits()) {
        fTextureCache->reattachAndUnlock(entry);
    } else {
        fTextureCache->unlock(entry);
    }
}

GrTexture* GrContext::createUncachedTexture(const GrTextureDesc& desc,
                                            void* srcData,
                                            size_t rowBytes) {
    return fGpu->createTexture(desc, srcData, rowBytes);
}

void GrContext::getTextureCacheLimits(int* maxTextures,
                                      size_t* maxTextureBytes) const {
    fTextureCache->getLimits(maxTextures, maxTextureBytes);
}

void GrContext::setTextureCacheLimits(int maxTextures, size_t maxTextureBytes) {
    fTextureCache->setLimits(maxTextures, maxTextureBytes);
}

int GrContext::getMaxTextureSize() const {
    return fGpu->maxTextureSize();
}

int GrContext::getMaxRenderTargetSize() const {
    return fGpu->maxRenderTargetSize();
}

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

GrResource* GrContext::createPlatformSurface(const GrPlatformSurfaceDesc& desc) {
    // validate flags here so that GrGpu subclasses don't have to check
    if (kTexture_GrPlatformSurfaceType == desc.fSurfaceType &&
        0 != desc.fRenderTargetFlags) {
            return NULL;
    }
    if (!(kIsMultisampled_GrPlatformRenderTargetFlagBit & desc.fRenderTargetFlags) &&
        (kGrCanResolve_GrPlatformRenderTargetFlagBit & desc.fRenderTargetFlags)) {
            return NULL;
    }
    if (kTextureRenderTarget_GrPlatformSurfaceType == desc.fSurfaceType &&
        (kIsMultisampled_GrPlatformRenderTargetFlagBit & desc.fRenderTargetFlags) &&
        !(kGrCanResolve_GrPlatformRenderTargetFlagBit & desc.fRenderTargetFlags)) {
        return NULL;
    }
    return fGpu->createPlatformSurface(desc);
}

GrRenderTarget* GrContext::createRenderTargetFrom3DApiState() {
    return fGpu->createRenderTargetFrom3DApiState();
}

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

bool GrContext::supportsIndex8PixelConfig(const GrSamplerState& sampler,
                                          int width, int height) {
    if (!fGpu->supports8BitPalette()) {
        return false;
    }


    bool isPow2 = GrIsPow2(width) && GrIsPow2(height);

    if (!isPow2) {
        if (!fGpu->npotTextureSupport()) {
            return false;
        }

        bool tiled = sampler.getWrapX() != GrSamplerState::kClamp_WrapMode ||
                     sampler.getWrapY() != GrSamplerState::kClamp_WrapMode;
        if (tiled && !fGpu->npotTextureTileSupport()) {
            return false;
        }
    }
    return true;
}

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

const GrClip& GrContext::getClip() const { return fGpu->getClip(); }

void GrContext::setClip(const GrClip& clip) {
    fGpu->setClip(clip);
    fGpu->enableState(GrDrawTarget::kClip_StateBit);
}

void GrContext::setClip(const GrIRect& rect) {
    GrClip clip;
    clip.setFromIRect(rect);
    fGpu->setClip(clip);
}

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

void GrContext::clear(const GrIRect* rect, const GrColor color) {
    this->flush();
    fGpu->clear(rect, color);
}

void GrContext::drawPaint(const GrPaint& paint) {
    // set rect to be big enough to fill the space, but not super-huge, so we
    // don't overflow fixed-point implementations
    GrRect r;
    r.setLTRB(0, 0,
              GrIntToScalar(getRenderTarget()->width()),
              GrIntToScalar(getRenderTarget()->height()));
    GrMatrix inverse;
    if (fGpu->getViewInverse(&inverse)) {
        inverse.mapRect(&r);
    } else {
        GrPrintf("---- fGpu->getViewInverse failed\n");
    }
    this->drawRect(paint, r);
}

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

struct GrContext::OffscreenRecord {
    OffscreenRecord() { fEntry0 = NULL; fEntry1 = NULL; }
    ~OffscreenRecord() { GrAssert(NULL == fEntry0 && NULL == fEntry1); }

    enum Downsample {
        k4x4TwoPass_Downsample,
        k4x4SinglePass_Downsample,
        kFSAA_Downsample
    }                              fDownsample;
    int                            fTileSizeX;
    int                            fTileSizeY;
    int                            fTileCountX;
    int                            fTileCountY;
    int                            fScale;
    GrTextureEntry*                fEntry0;
    GrTextureEntry*                fEntry1;
    GrDrawTarget::SavedDrawState   fSavedState;
    GrClip                         fClip;
};

bool GrContext::doOffscreenAA(GrDrawTarget* target, 
                              const GrPaint& paint,
                              bool isLines) const {
#if !GR_USE_OFFSCREEN_AA
    return false;
#else
    if (!paint.fAntiAlias) {
        return false;
    }
    if (isLines && fGpu->supportsAALines()) {
        return false;
    }
    if (target->getRenderTarget()->isMultisampled()) {
        return false;
    }
    // we have to be sure that the blend equation is expressible
    // as simple src / dst coeffecients when the source 
    // is already modulated by the coverage fraction.
    // We could use dual-source blending to get the correct per-pixel
    // dst coeffecient for the remaining cases.
    if (kISC_BlendCoeff != paint.fDstBlendCoeff &&
        kOne_BlendCoeff != paint.fDstBlendCoeff &&
        kISA_BlendCoeff != paint.fDstBlendCoeff) {
        return false;
    }
    return true;
#endif
}

bool GrContext::prepareForOffscreenAA(GrDrawTarget* target,
                                      bool requireStencil,
                                      const GrIRect& boundRect,
                                      GrPathRenderer* pr,
                                      OffscreenRecord* record) {

    GrAssert(GR_USE_OFFSCREEN_AA);

    GrAssert(NULL == record->fEntry0);
    GrAssert(NULL == record->fEntry1);
    GrAssert(!boundRect.isEmpty());

    int boundW = boundRect.width();
    int boundH = boundRect.height();

    GrTextureDesc desc;

    desc.fWidth  = GrMin(fMaxOffscreenAASize, boundW);
    desc.fHeight = GrMin(fMaxOffscreenAASize, boundH);

    if (requireStencil) {
        desc.fFlags = kRenderTarget_GrTextureFlagBit;
    } else {
        desc.fFlags = kRenderTarget_GrTextureFlagBit | 
                      kNoStencil_GrTextureFlagBit;
    }

    desc.fFormat = kRGBA_8888_GrPixelConfig;

    if (PREFER_MSAA_OFFSCREEN_AA && fGpu->supportsFullsceneAA()) {
        record->fDownsample = OffscreenRecord::kFSAA_Downsample;
        record->fScale = 1;
        desc.fAALevel = kMed_GrAALevel;
    } else {
        record->fDownsample = (fGpu->supports4x4DownsampleFilter()) ?
                                OffscreenRecord::k4x4SinglePass_Downsample :
                                OffscreenRecord::k4x4TwoPass_Downsample;
        record->fScale = OFFSCREEN_SSAA_SCALE;
        // both downsample paths assume this
        GR_STATIC_ASSERT(4 == OFFSCREEN_SSAA_SCALE);
        desc.fAALevel = kNone_GrAALevel;
    }
    // Avoid overtesselating paths in AA buffers; may unduly reduce quality
    // of simple circles?
    if (pr) {
        //pr->scaleCurveTolerance(GrIntToScalar(record->fScale));
    }
    
    desc.fWidth *= record->fScale;
    desc.fHeight *= record->fScale;

    record->fEntry0 = this->findApproximateKeylessTexture(desc);
    if (NULL == record->fEntry0) {
        return false;
    }
    // the approximate lookup might have given us some slop space, might as well
    // use it when computing the tiles size.
    // these are scale values, will adjust after considering
    // the possible second offscreen.
    record->fTileSizeX = record->fEntry0->texture()->width();
    record->fTileSizeY = record->fEntry0->texture()->height();

    if (OffscreenRecord::k4x4TwoPass_Downsample == record->fDownsample) {
        desc.fWidth /= 2;
        desc.fHeight /= 2;
        record->fEntry1 = this->findApproximateKeylessTexture(desc);
        if (NULL == record->fEntry1) {
            this->unlockTexture(record->fEntry0);
            record->fEntry0 = NULL;
            return false;
        }
        record->fTileSizeX = GrMin(record->fTileSizeX, 
                                   2 * record->fEntry0->texture()->width());
        record->fTileSizeY = GrMin(record->fTileSizeY, 
                                   2 * record->fEntry0->texture()->height());
    }
    record->fTileSizeX /= record->fScale;
    record->fTileSizeY /= record->fScale;

    record->fTileCountX = GrIDivRoundUp(boundW, record->fTileSizeX);
    record->fTileCountY = GrIDivRoundUp(boundH, record->fTileSizeY);

    record->fClip = target->getClip();

    target->saveCurrentDrawState(&record->fSavedState);
    return true;
}

void GrContext::setupOffscreenAAPass1(GrDrawTarget* target,
                                      const GrIRect& boundRect,
                                      int tileX, int tileY,
                                      OffscreenRecord* record) {

    GrRenderTarget* offRT0 = record->fEntry0->texture()->asRenderTarget();
    GrAssert(NULL != offRT0);

    GrPaint tempPaint;
    tempPaint.reset();
    SetPaint(tempPaint, target);
    target->setRenderTarget(offRT0);

    GrMatrix transM;
    int left = boundRect.fLeft + tileX * record->fTileSizeX;
    int top =  boundRect.fTop  + tileY * record->fTileSizeY;
    transM.setTranslate(-left * GR_Scalar1, -top * GR_Scalar1);
    target->postConcatViewMatrix(transM);
    GrMatrix scaleM;
    scaleM.setScale(record->fScale * GR_Scalar1, record->fScale * GR_Scalar1);
    target->postConcatViewMatrix(scaleM);

    int w = (tileX == record->fTileCountX-1) ? boundRect.fRight - left :
                                               record->fTileSizeX;
    int h = (tileY == record->fTileCountY-1) ? boundRect.fBottom - top :
                                               record->fTileSizeY;
    GrIRect clear = SkIRect::MakeWH(record->fScale * w, 
                                    record->fScale * h);
    target->setClip(GrClip(clear));
#if 0
    // visualize tile boundaries by setting edges of offscreen to white
    // and interior to tranparent. black.
    target->clear(&clear, 0xffffffff);

    static const int gOffset = 2;
    GrIRect clear2 = SkIRect::MakeLTRB(gOffset, gOffset,
                                       record->fScale * w - gOffset,
                                       record->fScale * h - gOffset);
    target->clear(&clear2, 0x0);
#else
    target->clear(&clear, 0x0);
#endif
}

void GrContext::doOffscreenAAPass2(GrDrawTarget* target,
                                 const GrPaint& paint,
                                 const GrIRect& boundRect,
                                 int tileX, int tileY,
                                 OffscreenRecord* record) {
    SK_TRACE_EVENT0("GrContext::doOffscreenAAPass2");
    GrAssert(NULL != record->fEntry0);
    GrDrawTarget::AutoGeometryPush agp(target);
    GrIRect tileRect;
    tileRect.fLeft = boundRect.fLeft + tileX * record->fTileSizeX;
    tileRect.fTop  = boundRect.fTop  + tileY * record->fTileSizeY,
    tileRect.fRight = (tileX == record->fTileCountX-1) ? 
                        boundRect.fRight :
                        tileRect.fLeft + record->fTileSizeX;
    tileRect.fBottom = (tileY == record->fTileCountY-1) ? 
                        boundRect.fBottom :
                        tileRect.fTop + record->fTileSizeY;

    GrSamplerState::Filter filter;
    if (OffscreenRecord::k4x4SinglePass_Downsample == record->fDownsample) {
        filter = GrSamplerState::k4x4Downsample_Filter;
    } else {
        filter = GrSamplerState::kBilinear_Filter;
    }

    GrMatrix sampleM;
    GrSamplerState sampler(GrSamplerState::kClamp_WrapMode, 
                           GrSamplerState::kClamp_WrapMode, filter);

    GrTexture* src = record->fEntry0->texture();
    int scale;

    enum {
        kOffscreenStage = GrPaint::kTotalStages,
    };

    if (OffscreenRecord::k4x4TwoPass_Downsample == record->fDownsample) {
        GrAssert(NULL != record->fEntry1);
        scale = 2;
        GrRenderTarget* dst = record->fEntry1->texture()->asRenderTarget();
        
        // Do 2x2 downsample from first to second
        target->setTexture(kOffscreenStage, src);
        target->setRenderTarget(dst);
        target->setViewMatrix(GrMatrix::I());
        sampleM.setScale(scale * GR_Scalar1 / src->width(),
                         scale * GR_Scalar1 / src->height());
        sampler.setMatrix(sampleM);
        target->setSamplerState(kOffscreenStage, sampler);
        GrRect rect = SkRect::MakeWH(scale * tileRect.width(),
                                     scale * tileRect.height());
        target->drawSimpleRect(rect, NULL, 1 << kOffscreenStage);
        
        src = record->fEntry1->texture();
    } else if (OffscreenRecord::kFSAA_Downsample == record->fDownsample) {
        scale = 1;
        GrIRect rect = SkIRect::MakeWH(tileRect.width(), tileRect.height());
        src->asRenderTarget()->overrideResolveRect(rect);
    } else {
        GrAssert(OffscreenRecord::k4x4SinglePass_Downsample == 
                 record->fDownsample);
        scale = 4;
    }

    // setup for draw back to main RT, we use the original
    // draw state setup by the caller plus an additional coverage
    // stage to handle the AA resolve. Also, we use an identity
    // view matrix and so pre-concat sampler matrices with view inv.
    int stageMask = paint.getActiveStageMask();

    target->restoreDrawState(record->fSavedState);
    target->setClip(record->fClip);

    if (stageMask) {
        GrMatrix invVM;
        if (target->getViewInverse(&invVM)) {
            target->preConcatSamplerMatrices(stageMask, invVM);
        }
    }
    // This is important when tiling, otherwise second tile's 
    // pass 1 view matrix will be incorrect.
    GrDrawTarget::AutoViewMatrixRestore avmr(target);

    target->setViewMatrix(GrMatrix::I());

    target->setTexture(kOffscreenStage, src);
    sampleM.setScale(scale * GR_Scalar1 / src->width(),
                     scale * GR_Scalar1 / src->height());
    sampler.setMatrix(sampleM);
    sampleM.setTranslate(-tileRect.fLeft, -tileRect.fTop);
    sampler.preConcatMatrix(sampleM);
    target->setSamplerState(kOffscreenStage, sampler);

    GrRect dstRect;
    int stages = (1 << kOffscreenStage) | stageMask;
    dstRect.set(tileRect);
    target->drawSimpleRect(dstRect, NULL, stages);
}

void GrContext::cleanupOffscreenAA(GrDrawTarget* target,
                                   GrPathRenderer* pr,
                                   OffscreenRecord* record) {
    this->unlockTexture(record->fEntry0);
    record->fEntry0 = NULL;
    if (pr) {
        // Counterpart of scale() in prepareForOffscreenAA()
        //pr->scaleCurveTolerance(SkScalarInvert(SkIntToScalar(record->fScale)));
    }
    if (NULL != record->fEntry1) {
        this->unlockTexture(record->fEntry1);
        record->fEntry1 = NULL;
    }
    target->restoreDrawState(record->fSavedState);
}

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

/*  create a triangle strip that strokes the specified triangle. There are 8
 unique vertices, but we repreat the last 2 to close up. Alternatively we
 could use an indices array, and then only send 8 verts, but not sure that
 would be faster.
 */
static void setStrokeRectStrip(GrPoint verts[10], GrRect rect,
                               GrScalar width) {
    const GrScalar rad = GrScalarHalf(width);
    rect.sort();

    verts[0].set(rect.fLeft + rad, rect.fTop + rad);
    verts[1].set(rect.fLeft - rad, rect.fTop - rad);
    verts[2].set(rect.fRight - rad, rect.fTop + rad);
    verts[3].set(rect.fRight + rad, rect.fTop - rad);
    verts[4].set(rect.fRight - rad, rect.fBottom - rad);
    verts[5].set(rect.fRight + rad, rect.fBottom + rad);
    verts[6].set(rect.fLeft + rad, rect.fBottom - rad);
    verts[7].set(rect.fLeft - rad, rect.fBottom + rad);
    verts[8] = verts[0];
    verts[9] = verts[1];
}

static GrColor getColorForMesh(const GrPaint& paint) {
    // FIXME: This was copied from SkGpuDevice, seems like
    // we should have already smeared a in caller if that
    // is what is desired.
    if (paint.hasTexture()) {
        unsigned a = GrColorUnpackA(paint.fColor);
        return GrColorPackRGBA(a, a, a, a);
    } else {
        return paint.fColor;
    }
}

static void setInsetFan(GrPoint* pts, size_t stride,
                        const GrRect& r, GrScalar dx, GrScalar dy) {
    pts->setRectFan(r.fLeft + dx, r.fTop + dy, r.fRight - dx, r.fBottom - dy, stride);
}

static const uint16_t gFillAARectIdx[] = {
    0, 1, 5, 5, 4, 0,
    1, 2, 6, 6, 5, 1,
    2, 3, 7, 7, 6, 2,
    3, 0, 4, 4, 7, 3,
    4, 5, 6, 6, 7, 4,
};

int GrContext::aaFillRectIndexCount() const {
    return GR_ARRAY_COUNT(gFillAARectIdx);
}

GrIndexBuffer* GrContext::aaFillRectIndexBuffer() {
    if (NULL == fAAFillRectIndexBuffer) {
        fAAFillRectIndexBuffer = fGpu->createIndexBuffer(sizeof(gFillAARectIdx),
                                                         false);
        GrAssert(NULL != fAAFillRectIndexBuffer);
#if GR_DEBUG
        bool updated =
#endif
        fAAFillRectIndexBuffer->updateData(gFillAARectIdx,
                                           sizeof(gFillAARectIdx));
        GR_DEBUGASSERT(updated);
    }
    return fAAFillRectIndexBuffer;
}

static const uint16_t gStrokeAARectIdx[] = {
    0 + 0, 1 + 0, 5 + 0, 5 + 0, 4 + 0, 0 + 0,
    1 + 0, 2 + 0, 6 + 0, 6 + 0, 5 + 0, 1 + 0,
    2 + 0, 3 + 0, 7 + 0, 7 + 0, 6 + 0, 2 + 0,
    3 + 0, 0 + 0, 4 + 0, 4 + 0, 7 + 0, 3 + 0,

    0 + 4, 1 + 4, 5 + 4, 5 + 4, 4 + 4, 0 + 4,
    1 + 4, 2 + 4, 6 + 4, 6 + 4, 5 + 4, 1 + 4,
    2 + 4, 3 + 4, 7 + 4, 7 + 4, 6 + 4, 2 + 4,
    3 + 4, 0 + 4, 4 + 4, 4 + 4, 7 + 4, 3 + 4,

    0 + 8, 1 + 8, 5 + 8, 5 + 8, 4 + 8, 0 + 8,
    1 + 8, 2 + 8, 6 + 8, 6 + 8, 5 + 8, 1 + 8,
    2 + 8, 3 + 8, 7 + 8, 7 + 8, 6 + 8, 2 + 8,
    3 + 8, 0 + 8, 4 + 8, 4 + 8, 7 + 8, 3 + 8,
};

int GrContext::aaStrokeRectIndexCount() const {
    return GR_ARRAY_COUNT(gStrokeAARectIdx);
}

GrIndexBuffer* GrContext::aaStrokeRectIndexBuffer() {
    if (NULL == fAAStrokeRectIndexBuffer) {
        fAAStrokeRectIndexBuffer = fGpu->createIndexBuffer(sizeof(gStrokeAARectIdx),
                                                           false);
        GrAssert(NULL != fAAStrokeRectIndexBuffer);
#if GR_DEBUG
        bool updated =
#endif
        fAAStrokeRectIndexBuffer->updateData(gStrokeAARectIdx,
                                             sizeof(gStrokeAARectIdx));
        GR_DEBUGASSERT(updated);
    }
    return fAAStrokeRectIndexBuffer;
}

void GrContext::fillAARect(GrDrawTarget* target,
                           const GrPaint& paint,
                           const GrRect& devRect) {
    GrVertexLayout layout = PaintStageVertexLayoutBits(paint, NULL) |
                            GrDrawTarget::kColor_VertexLayoutBit;

    size_t vsize = GrDrawTarget::VertexSize(layout);

    GrDrawTarget::AutoReleaseGeometry geo(target, layout, 8, 0);

    intptr_t verts = reinterpret_cast<intptr_t>(geo.vertices());

    GrPoint* fan0Pos = reinterpret_cast<GrPoint*>(verts);
    GrPoint* fan1Pos = reinterpret_cast<GrPoint*>(verts + 4 * vsize);

    setInsetFan(fan0Pos, vsize, devRect, -GR_ScalarHalf, -GR_ScalarHalf);
    setInsetFan(fan1Pos, vsize, devRect,  GR_ScalarHalf,  GR_ScalarHalf);

    verts += sizeof(GrPoint);
    for (int i = 0; i < 4; ++i) {
        *reinterpret_cast<GrColor*>(verts + i * vsize) = 0;
    }

    GrColor innerColor = getColorForMesh(paint);
    verts += 4 * vsize;
    for (int i = 0; i < 4; ++i) {
        *reinterpret_cast<GrColor*>(verts + i * vsize) = innerColor;
    }

    target->setIndexSourceToBuffer(this->aaFillRectIndexBuffer());

    target->drawIndexed(kTriangles_PrimitiveType, 0,
                         0, 8, this->aaFillRectIndexCount());
}

void GrContext::strokeAARect(GrDrawTarget* target, const GrPaint& paint,
                             const GrRect& devRect, const GrVec& devStrokeSize) {
    const GrScalar& dx = devStrokeSize.fX;
    const GrScalar& dy = devStrokeSize.fY;
    const GrScalar rx = GrMul(dx, GR_ScalarHalf);
    const GrScalar ry = GrMul(dy, GR_ScalarHalf);

    GrVertexLayout layout = PaintStageVertexLayoutBits(paint, NULL) |
                            GrDrawTarget::kColor_VertexLayoutBit;

    GrScalar spare;
    {
        GrScalar w = devRect.width() - dx;
        GrScalar h = devRect.height() - dy;
        spare = GrMin(w, h);
    }

    if (spare <= 0) {
        GrRect r(devRect);
        r.inset(-rx, -ry);
        fillAARect(target, paint, r);
        return;
    }

    size_t vsize = GrDrawTarget::VertexSize(layout);

    GrDrawTarget::AutoReleaseGeometry geo(target, layout, 16, 0);

    intptr_t verts = reinterpret_cast<intptr_t>(geo.vertices());

    GrPoint* fan0Pos = reinterpret_cast<GrPoint*>(verts);
    GrPoint* fan1Pos = reinterpret_cast<GrPoint*>(verts + 4 * vsize);
    GrPoint* fan2Pos = reinterpret_cast<GrPoint*>(verts + 8 * vsize);
    GrPoint* fan3Pos = reinterpret_cast<GrPoint*>(verts + 12 * vsize);

    setInsetFan(fan0Pos, vsize, devRect, -rx - GR_ScalarHalf, -ry - GR_ScalarHalf);
    setInsetFan(fan1Pos, vsize, devRect, -rx + GR_ScalarHalf, -ry + GR_ScalarHalf);
    setInsetFan(fan2Pos, vsize, devRect,  rx - GR_ScalarHalf,  ry - GR_ScalarHalf);
    setInsetFan(fan3Pos, vsize, devRect,  rx + GR_ScalarHalf,  ry + GR_ScalarHalf);

    verts += sizeof(GrPoint);
    for (int i = 0; i < 4; ++i) {
        *reinterpret_cast<GrColor*>(verts + i * vsize) = 0;
    }

    GrColor innerColor = getColorForMesh(paint);
    verts += 4 * vsize;
    for (int i = 0; i < 8; ++i) {
        *reinterpret_cast<GrColor*>(verts + i * vsize) = innerColor;
    }

    verts += 8 * vsize;
    for (int i = 0; i < 8; ++i) {
        *reinterpret_cast<GrColor*>(verts + i * vsize) = 0;
    }

    target->setIndexSourceToBuffer(aaStrokeRectIndexBuffer());
    target->drawIndexed(kTriangles_PrimitiveType,
                        0, 0, 16, aaStrokeRectIndexCount());
}

/**
 * Returns true if the rects edges are integer-aligned.
 */
static bool isIRect(const GrRect& r) {
    return GrScalarIsInt(r.fLeft) && GrScalarIsInt(r.fTop) && 
           GrScalarIsInt(r.fRight) && GrScalarIsInt(r.fBottom);
}

static bool apply_aa_to_rect(GrDrawTarget* target,
                             GrGpu* gpu,
                             const GrPaint& paint,
                             const GrRect& rect,
                             GrScalar width, 
                             const GrMatrix* matrix,
                             GrMatrix* combinedMatrix,
                             GrRect* devRect) {
    // we use a simple alpha ramp to do aa on axis-aligned rects
    // do AA with alpha ramp if the caller requested AA, the rect 
    // will be axis-aligned,the render target is not
    // multisampled, and the rect won't land on integer coords.

    if (!paint.fAntiAlias) {
        return false;
    }

    if (target->getRenderTarget()->isMultisampled()) {
        return false;
    }

    if (0 == width && gpu->supportsAALines()) {
        return false;
    }

    if (!target->getViewMatrix().preservesAxisAlignment()) {
        return false;
    }

    if (NULL != matrix && 
        !matrix->preservesAxisAlignment()) {
        return false;
    }

    *combinedMatrix = target->getViewMatrix();
    if (NULL != matrix) {
        combinedMatrix->preConcat(*matrix);
        GrAssert(combinedMatrix->preservesAxisAlignment());
    }
    
    combinedMatrix->mapRect(devRect, rect);
    devRect->sort();

    if (width < 0) {
        return !isIRect(*devRect);
    } else {
        return true;
    }
}

void GrContext::drawRect(const GrPaint& paint,
                         const GrRect& rect,
                         GrScalar width,
                         const GrMatrix* matrix) {
    SK_TRACE_EVENT0("GrContext::drawRect");

    GrDrawTarget* target = this->prepareToDraw(paint, kUnbuffered_DrawCategory);
    int stageMask = paint.getActiveStageMask();

    GrRect devRect = rect;
    GrMatrix combinedMatrix;
    bool doAA = apply_aa_to_rect(target, fGpu, paint, rect, width, matrix, 
                                 &combinedMatrix, &devRect);

    if (doAA) {
        GrDrawTarget::AutoViewMatrixRestore avm(target);
        if (stageMask) {
            GrMatrix inv;
            if (combinedMatrix.invert(&inv)) {
                target->preConcatSamplerMatrices(stageMask, inv);
            }
        }
        target->setViewMatrix(GrMatrix::I());
        if (width >= 0) {
            GrVec strokeSize;;
            if (width > 0) {
                strokeSize.set(width, width);
                combinedMatrix.mapVectors(&strokeSize, 1);
                strokeSize.setAbs(strokeSize);
            } else {
                strokeSize.set(GR_Scalar1, GR_Scalar1);
            }
            strokeAARect(target, paint, devRect, strokeSize);
        } else {
            fillAARect(target, paint, devRect);
        }
        return;
    }

    if (width >= 0) {
        // TODO: consider making static vertex buffers for these cases.
        // Hairline could be done by just adding closing vertex to
        // unitSquareVertexBuffer()
        GrVertexLayout layout =  PaintStageVertexLayoutBits(paint, NULL);

        static const int worstCaseVertCount = 10;
        GrDrawTarget::AutoReleaseGeometry geo(target, layout, worstCaseVertCount, 0);

        if (!geo.succeeded()) {
            return;
        }

        GrPrimitiveType primType;
        int vertCount;
        GrPoint* vertex = geo.positions();

        if (width > 0) {
            vertCount = 10;
            primType = kTriangleStrip_PrimitiveType;
            setStrokeRectStrip(vertex, rect, width);
        } else {
            // hairline
            vertCount = 5;
            primType = kLineStrip_PrimitiveType;
            vertex[0].set(rect.fLeft, rect.fTop);
            vertex[1].set(rect.fRight, rect.fTop);
            vertex[2].set(rect.fRight, rect.fBottom);
            vertex[3].set(rect.fLeft, rect.fBottom);
            vertex[4].set(rect.fLeft, rect.fTop);
        }

        GrDrawTarget::AutoViewMatrixRestore avmr;
        if (NULL != matrix) {
            avmr.set(target);
            target->preConcatViewMatrix(*matrix);
            target->preConcatSamplerMatrices(stageMask, *matrix);
        }

        target->drawNonIndexed(primType, 0, vertCount);
    } else {
        #if GR_STATIC_RECT_VB
            GrVertexLayout layout = PaintStageVertexLayoutBits(paint, NULL);

            target->setVertexSourceToBuffer(layout,
                                            fGpu->getUnitSquareVertexBuffer());
            GrDrawTarget::AutoViewMatrixRestore avmr(target);
            GrMatrix m;
            m.setAll(rect.width(),    0,             rect.fLeft,
                        0,            rect.height(), rect.fTop,
                        0,            0,             GrMatrix::I()[8]);

            if (NULL != matrix) {
                m.postConcat(*matrix);
            }

            target->preConcatViewMatrix(m);
            target->preConcatSamplerMatrices(stageMask, m);
 
            target->drawNonIndexed(kTriangleFan_PrimitiveType, 0, 4);
        #else
            target->drawSimpleRect(rect, matrix, stageMask);
        #endif
    }
}

void GrContext::drawRectToRect(const GrPaint& paint,
                               const GrRect& dstRect,
                               const GrRect& srcRect,
                               const GrMatrix* dstMatrix,
                               const GrMatrix* srcMatrix) {
    SK_TRACE_EVENT0("GrContext::drawRectToRect");

    // srcRect refers to paint's first texture
    if (NULL == paint.getTexture(0)) {
        drawRect(paint, dstRect, -1, dstMatrix);
        return;
    }

    GR_STATIC_ASSERT(!BATCH_RECT_TO_RECT || !GR_STATIC_RECT_VB);

#if GR_STATIC_RECT_VB
    GrDrawTarget* target = this->prepareToDraw(paint, kUnbuffered_DrawCategory);
    
    GrVertexLayout layout = PaintStageVertexLayoutBits(paint, NULL);
    GrDrawTarget::AutoViewMatrixRestore avmr(target);

    GrMatrix m;

    m.setAll(dstRect.width(), 0,                dstRect.fLeft,
             0,               dstRect.height(), dstRect.fTop,
             0,               0,                GrMatrix::I()[8]);
    if (NULL != dstMatrix) {
        m.postConcat(*dstMatrix);
    }
    target->preConcatViewMatrix(m);

    // srcRect refers to first stage
    int otherStageMask = paint.getActiveStageMask() & 
                         (~(1 << GrPaint::kFirstTextureStage));
    if (otherStageMask) {
        target->preConcatSamplerMatrices(otherStageMask, m);
    }

    m.setAll(srcRect.width(), 0,                srcRect.fLeft,
             0,               srcRect.height(), srcRect.fTop,
             0,               0,                GrMatrix::I()[8]);
    if (NULL != srcMatrix) {
        m.postConcat(*srcMatrix);
    }
    target->preConcatSamplerMatrix(GrPaint::kFirstTextureStage, m);

    target->setVertexSourceToBuffer(layout, fGpu->getUnitSquareVertexBuffer());
    target->drawNonIndexed(kTriangleFan_PrimitiveType, 0, 4);
#else

    GrDrawTarget* target;
#if BATCH_RECT_TO_RECT
    target = this->prepareToDraw(paint, kBuffered_DrawCategory);
#else
    target = this->prepareToDraw(paint, kUnbuffered_DrawCategory);
#endif

    const GrRect* srcRects[GrDrawTarget::kNumStages] = {NULL};
    const GrMatrix* srcMatrices[GrDrawTarget::kNumStages] = {NULL};
    srcRects[0] = &srcRect;
    srcMatrices[0] = srcMatrix;

    target->drawRect(dstRect, dstMatrix, 1, srcRects, srcMatrices);
#endif
}

void GrContext::drawVertices(const GrPaint& paint,
                             GrPrimitiveType primitiveType,
                             int vertexCount,
                             const GrPoint positions[],
                             const GrPoint texCoords[],
                             const GrColor colors[],
                             const uint16_t indices[],
                             int indexCount) {
    SK_TRACE_EVENT0("GrContext::drawVertices");

    GrDrawTarget::AutoReleaseGeometry geo;

    GrDrawTarget* target = this->prepareToDraw(paint, kUnbuffered_DrawCategory);

    bool hasTexCoords[GrPaint::kTotalStages] = {
        NULL != texCoords,   // texCoordSrc provides explicit stage 0 coords
        0                    // remaining stages use positions
    };

    GrVertexLayout layout = PaintStageVertexLayoutBits(paint, hasTexCoords);

    if (NULL != colors) {
        layout |= GrDrawTarget::kColor_VertexLayoutBit;
    }
    int vertexSize = GrDrawTarget::VertexSize(layout);

    if (sizeof(GrPoint) != vertexSize) {
        if (!geo.set(target, layout, vertexCount, 0)) {
            GrPrintf("Failed to get space for vertices!");
            return;
        }
        int texOffsets[GrDrawTarget::kMaxTexCoords];
        int colorOffset;
        GrDrawTarget::VertexSizeAndOffsetsByIdx(layout,
                                                texOffsets,
                                                &colorOffset);
        void* curVertex = geo.vertices();

        for (int i = 0; i < vertexCount; ++i) {
            *((GrPoint*)curVertex) = positions[i];

            if (texOffsets[0] > 0) {
                *(GrPoint*)((intptr_t)curVertex + texOffsets[0]) = texCoords[i];
            }
            if (colorOffset > 0) {
                *(GrColor*)((intptr_t)curVertex + colorOffset) = colors[i];
            }
            curVertex = (void*)((intptr_t)curVertex + vertexSize);
        }
    } else {
        target->setVertexSourceToArray(layout, positions, vertexCount);
    }

    // we don't currently apply offscreen AA to this path. Need improved 
    // management of GrDrawTarget's geometry to avoid copying points per-tile.

    if (NULL != indices) {
        target->setIndexSourceToArray(indices, indexCount);
        target->drawIndexed(primitiveType, 0, 0, vertexCount, indexCount);
    } else {
        target->drawNonIndexed(primitiveType, 0, vertexCount);
    }
}

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

void GrContext::drawPath(const GrPaint& paint, const GrPath& path,
                         GrPathFill fill, const GrPoint* translate) {

    GrDrawTarget* target = this->prepareToDraw(paint, kUnbuffered_DrawCategory);
    GrPathRenderer* pr = this->getPathRenderer(path, fill);
    GrPathRenderer::AutoClearPath arp(pr, target, &path, fill, translate);
    GrDrawTarget::StageBitfield stageMask = paint.getActiveStageMask();

    if (!pr->supportsAA(target, path, fill) &&
        this->doOffscreenAA(target, paint, kHairLine_PathFill == fill)) {

        bool needsStencil = pr->requiresStencilPass(target, path, fill);

        // compute bounds as intersection of rt size, clip, and path
        GrIRect bound = SkIRect::MakeWH(target->getRenderTarget()->width(), 
                                        target->getRenderTarget()->height());
        GrIRect clipIBounds;
        if (target->getClip().hasConservativeBounds()) {
            target->getClip().getConservativeBounds().roundOut(&clipIBounds);
            if (!bound.intersect(clipIBounds)) {
                return;
            }
        }

        GrRect pathBounds = path.getBounds();
        if (!pathBounds.isEmpty()) {
            if (NULL != translate) {
                pathBounds.offset(*translate);
            }
            target->getViewMatrix().mapRect(&pathBounds, pathBounds);
            GrIRect pathIBounds;
            pathBounds.roundOut(&pathIBounds);
            if (!bound.intersect(pathIBounds)) {
                return;
            }
        }
        OffscreenRecord record;
        if (this->prepareForOffscreenAA(target, needsStencil, bound,
                                        pr, &record)) {
            for (int tx = 0; tx < record.fTileCountX; ++tx) {
                for (int ty = 0; ty < record.fTileCountY; ++ty) {
                    this->setupOffscreenAAPass1(target, bound, tx, ty, &record);
                    pr->drawPath(0);
                    this->doOffscreenAAPass2(target, paint, bound, tx, ty, &record);
                }
            }
            this->cleanupOffscreenAA(target, pr, &record);
            if (IsFillInverted(fill) && bound != clipIBounds) {
                GrDrawTarget::AutoDeviceCoordDraw adcd(target, stageMask);
                GrRect rect;
                if (clipIBounds.fTop < bound.fTop) {
                    rect.setLTRB(clipIBounds.fLeft, clipIBounds.fTop, 
                                 clipIBounds.fRight, bound.fTop);
                    target->drawSimpleRect(rect, NULL, stageMask);
                }
                if (clipIBounds.fLeft < bound.fLeft) {
                    rect.setLTRB(clipIBounds.fLeft, bound.fTop, 
                                 bound.fLeft, bound.fBottom);
                    target->drawSimpleRect(rect, NULL, stageMask);
                }
                if (clipIBounds.fRight > bound.fRight) {
                    rect.setLTRB(bound.fRight, bound.fTop, 
                                 clipIBounds.fRight, bound.fBottom);
                    target->drawSimpleRect(rect, NULL, stageMask);
                }
                if (clipIBounds.fBottom > bound.fBottom) {
                    rect.setLTRB(clipIBounds.fLeft, bound.fBottom, 
                                 clipIBounds.fRight, clipIBounds.fBottom);
                    target->drawSimpleRect(rect, NULL, stageMask);
                }
            }
            return;
        }
    } 
    pr->drawPath(stageMask);
}

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

void GrContext::flush(int flagsBitfield) {
    if (kDiscard_FlushBit & flagsBitfield) {
        fDrawBuffer->reset();
    } else {
        flushDrawBuffer();
    }

    if (kForceCurrentRenderTarget_FlushBit & flagsBitfield) {
        fGpu->forceRenderTargetFlush();
    }
}

void GrContext::flushText() {
    if (kText_DrawCategory == fLastDrawCategory) {
        flushDrawBuffer();
    }
}

void GrContext::flushDrawBuffer() {
#if BATCH_RECT_TO_RECT || DEFER_TEXT_RENDERING
    if (fDrawBuffer) {
        fDrawBuffer->playback(fGpu);
        fDrawBuffer->reset();
    }
#endif
}

bool GrContext::readTexturePixels(GrTexture* texture,
                                  int left, int top, int width, int height,
                                  GrPixelConfig config, void* buffer) {
    SK_TRACE_EVENT0("GrContext::readTexturePixels");

    // TODO: code read pixels for textures that aren't rendertargets

    this->flush();
    GrRenderTarget* target = texture->asRenderTarget();
    if (NULL != target) {
        return fGpu->readPixels(target,
                                left, top, width, height, 
                                config, buffer);
    } else {
        return false;
    }
}

bool GrContext::readRenderTargetPixels(GrRenderTarget* target,
                                      int left, int top, int width, int height,
                                      GrPixelConfig config, void* buffer) {
    SK_TRACE_EVENT0("GrContext::readRenderTargetPixels");
    uint32_t flushFlags = 0;
    if (NULL == target) { 
        flushFlags |= GrContext::kForceCurrentRenderTarget_FlushBit;
    }

    this->flush(flushFlags);
    return fGpu->readPixels(target,
                            left, top, width, height, 
                            config, buffer);
}

void GrContext::writePixels(int left, int top, int width, int height,
                            GrPixelConfig config, const void* buffer,
                            size_t stride) {
    SK_TRACE_EVENT0("GrContext::writePixels");

    // TODO: when underlying api has a direct way to do this we should use it
    // (e.g. glDrawPixels on desktop GL).

    this->flush(true);

    const GrTextureDesc desc = {
        kNone_GrTextureFlags, kNone_GrAALevel, width, height, config
    };
    GrAutoUnlockTextureEntry aute(this,
                                    this->findApproximateKeylessTexture(desc));
    GrTexture* texture = aute.texture();
    if (NULL == texture) {
        return;
    }
    texture->uploadTextureData(0, 0, width, height, buffer, stride);

    GrDrawTarget::AutoStateRestore  asr(fGpu);

    GrMatrix matrix;
    matrix.setTranslate(GrIntToScalar(left), GrIntToScalar(top));
    fGpu->setViewMatrix(matrix);

    fGpu->setColorFilter(0, SkXfermode::kDst_Mode);
    fGpu->disableState(GrDrawTarget::kClip_StateBit);
    fGpu->setAlpha(0xFF);
    fGpu->setBlendFunc(kOne_BlendCoeff,
                       kZero_BlendCoeff);
    fGpu->setTexture(0, texture);

    GrSamplerState sampler;
    sampler.setClampNoFilter();
    matrix.setIDiv(texture->width(), texture->height());
    sampler.setMatrix(matrix);
    fGpu->setSamplerState(0, sampler);

    GrVertexLayout layout = GrDrawTarget::StagePosAsTexCoordVertexLayoutBit(0);
    static const int VCOUNT = 4;

    GrDrawTarget::AutoReleaseGeometry geo(fGpu, layout, VCOUNT, 0);
    if (!geo.succeeded()) {
        return;
    }
    ((GrPoint*)geo.vertices())->setIRectFan(0, 0, width, height);
    fGpu->drawNonIndexed(kTriangleFan_PrimitiveType, 0, VCOUNT);
}
////////////////////////////////////////////////////////////////////////////////

void GrContext::SetPaint(const GrPaint& paint, GrDrawTarget* target) {

    for (int i = 0; i < GrPaint::kMaxTextures; ++i) {
        int s = i + GrPaint::kFirstTextureStage;
        target->setTexture(s, paint.getTexture(i));
        target->setSamplerState(s, *paint.getTextureSampler(i));
    }

    target->setFirstCoverageStage(GrPaint::kFirstMaskStage);

    for (int i = 0; i < GrPaint::kMaxMasks; ++i) {
        int s = i + GrPaint::kFirstMaskStage;
        target->setTexture(s, paint.getMask(i));
        target->setSamplerState(s, *paint.getMaskSampler(i));
    }

    target->setColor(paint.fColor);

    if (paint.fDither) {
        target->enableState(GrDrawTarget::kDither_StateBit);
    } else {
        target->disableState(GrDrawTarget::kDither_StateBit);
    }
    if (paint.fAntiAlias) {
        target->enableState(GrDrawTarget::kAntialias_StateBit);
    } else {
        target->disableState(GrDrawTarget::kAntialias_StateBit);
    }
    target->setBlendFunc(paint.fSrcBlendCoeff, paint.fDstBlendCoeff);
    target->setColorFilter(paint.fColorFilterColor, paint.fColorFilterXfermode);
}

GrDrawTarget* GrContext::prepareToDraw(const GrPaint& paint,
                                       DrawCategory category) {
    if (category != fLastDrawCategory) {
        flushDrawBuffer();
        fLastDrawCategory = category;
    }
    SetPaint(paint, fGpu);
    GrDrawTarget* target = fGpu;
    switch (category) {
    case kText_DrawCategory:
#if DEFER_TEXT_RENDERING
        target = fDrawBuffer;
        fDrawBuffer->initializeDrawStateAndClip(*fGpu);
#else
        target = fGpu;
#endif
        break;
    case kUnbuffered_DrawCategory:
        target = fGpu;
        break;
    case kBuffered_DrawCategory:
        target = fDrawBuffer;
        fDrawBuffer->initializeDrawStateAndClip(*fGpu);
        break;
    }
    return target;
}

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

void GrContext::setRenderTarget(GrRenderTarget* target) {
    this->flush(false);
    fGpu->setRenderTarget(target);
}

GrRenderTarget* GrContext::getRenderTarget() {
    return fGpu->getRenderTarget();
}

const GrRenderTarget* GrContext::getRenderTarget() const {
    return fGpu->getRenderTarget();
}

const GrMatrix& GrContext::getMatrix() const {
    return fGpu->getViewMatrix();
}

void GrContext::setMatrix(const GrMatrix& m) {
    fGpu->setViewMatrix(m);
}

void GrContext::concatMatrix(const GrMatrix& m) const {
    fGpu->preConcatViewMatrix(m);
}

static inline intptr_t setOrClear(intptr_t bits, int shift, intptr_t pred) {
    intptr_t mask = 1 << shift;
    if (pred) {
        bits |= mask;
    } else {
        bits &= ~mask;
    }
    return bits;
}

void GrContext::resetStats() {
    fGpu->resetStats();
}

const GrGpuStats& GrContext::getStats() const {
    return fGpu->getStats();
}

void GrContext::printStats() const {
    fGpu->printStats();
}

GrContext::GrContext(GrGpu* gpu) :
    fDefaultPathRenderer(gpu->supportsTwoSidedStencil(),
                         gpu->supportsStencilWrapOps()) {

    fGpu = gpu;
    fGpu->ref();
    fGpu->setContext(this);

    fCustomPathRenderer = GrPathRenderer::CreatePathRenderer();
    fGpu->setClipPathRenderer(fCustomPathRenderer);

    fTextureCache = new GrTextureCache(MAX_TEXTURE_CACHE_COUNT,
                                       MAX_TEXTURE_CACHE_BYTES);
    fFontCache = new GrFontCache(fGpu);

    fLastDrawCategory = kUnbuffered_DrawCategory;

    fDrawBuffer = NULL;
    fDrawBufferVBAllocPool = NULL;
    fDrawBufferIBAllocPool = NULL;

    fAAFillRectIndexBuffer = NULL;
    fAAStrokeRectIndexBuffer = NULL;
    
    int gpuMaxOffscreen = fGpu->maxRenderTargetSize();
    if (!PREFER_MSAA_OFFSCREEN_AA || !fGpu->supportsFullsceneAA()) {
        gpuMaxOffscreen /= OFFSCREEN_SSAA_SCALE;
    }
    fMaxOffscreenAASize = GrMin(GR_MAX_OFFSCREEN_AA_SIZE, gpuMaxOffscreen);

    this->setupDrawBuffer();
}

void GrContext::setupDrawBuffer() {

    GrAssert(NULL == fDrawBuffer);
    GrAssert(NULL == fDrawBufferVBAllocPool);
    GrAssert(NULL == fDrawBufferIBAllocPool);

#if DEFER_TEXT_RENDERING || BATCH_RECT_TO_RECT
    fDrawBufferVBAllocPool =
        new GrVertexBufferAllocPool(fGpu, false,
                                    DRAW_BUFFER_VBPOOL_BUFFER_SIZE,
                                    DRAW_BUFFER_VBPOOL_PREALLOC_BUFFERS);
    fDrawBufferIBAllocPool =
        new GrIndexBufferAllocPool(fGpu, false,
                                   DRAW_BUFFER_IBPOOL_BUFFER_SIZE,
                                   DRAW_BUFFER_IBPOOL_PREALLOC_BUFFERS);

    fDrawBuffer = new GrInOrderDrawBuffer(fDrawBufferVBAllocPool,
                                          fDrawBufferIBAllocPool);
#endif

#if BATCH_RECT_TO_RECT
    fDrawBuffer->setQuadIndexBuffer(this->getQuadIndexBuffer());
#endif
}

GrDrawTarget* GrContext::getTextTarget(const GrPaint& paint) {
    GrDrawTarget* target;
#if DEFER_TEXT_RENDERING
    target = prepareToDraw(paint, kText_DrawCategory);
#else
    target = prepareToDraw(paint, kUnbuffered_DrawCategory);
#endif
    SetPaint(paint, target);
    return target;
}

const GrIndexBuffer* GrContext::getQuadIndexBuffer() const {
    return fGpu->getQuadIndexBuffer();
}

GrPathRenderer* GrContext::getPathRenderer(const GrPath& path,
                                           GrPathFill fill) {
    if (NULL != fCustomPathRenderer &&
        fCustomPathRenderer->canDrawPath(path, fill)) {
        return fCustomPathRenderer;
    } else {
        GrAssert(fDefaultPathRenderer.canDrawPath(path, fill));
        return &fDefaultPathRenderer;
    }
}

void GrContext::convolveInX(GrTexture* texture,
                            const SkRect& rect,
                            const float* kernel,
                            int kernelWidth) {
    float imageIncrement[2] = {1.0f / texture->width(), 0.0f};
    convolve(texture, rect, imageIncrement, kernel, kernelWidth);
}

void GrContext::convolveInY(GrTexture* texture,
                            const SkRect& rect,
                            const float* kernel,
                            int kernelWidth) {
    float imageIncrement[2] = {0.0f, 1.0f / texture->height()};
    convolve(texture, rect, imageIncrement, kernel, kernelWidth);
}

void GrContext::convolve(GrTexture* texture,
                         const SkRect& rect,
                         float imageIncrement[2],
                         const float* kernel,
                         int kernelWidth) {
    GrDrawTarget::AutoStateRestore asr(fGpu);
    GrMatrix sampleM;
    GrSamplerState sampler(GrSamplerState::kClamp_WrapMode, 
                           GrSamplerState::kClamp_WrapMode,
                           GrSamplerState::kConvolution_Filter);
    sampler.setConvolutionParams(kernelWidth, kernel, imageIncrement);
    sampleM.setScale(GR_Scalar1 / texture->width(),
                     GR_Scalar1 / texture->height());
    sampler.setMatrix(sampleM);
    fGpu->setSamplerState(0, sampler);
    fGpu->setViewMatrix(GrMatrix::I());
    fGpu->setTexture(0, texture);
    fGpu->setBlendFunc(kOne_BlendCoeff, kZero_BlendCoeff);
    fGpu->drawSimpleRect(rect, NULL, 1 << 0);
}