path: root/src/gpu/GrInOrderDrawBuffer.cpp

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#include "GrInOrderDrawBuffer.h"
#include "GrBufferAllocPool.h"
#include "GrDrawTargetCaps.h"
#include "GrGpu.h"
#include "GrIndexBuffer.h"
#include "GrPath.h"
#include "GrRenderTarget.h"
#include "GrTemplates.h"
#include "GrTexture.h"
#include "GrVertexBuffer.h"

GrInOrderDrawBuffer::GrInOrderDrawBuffer(GrGpu* gpu,
                                         GrVertexBufferAllocPool* vertexPool,
                                         GrIndexBufferAllocPool* indexPool)
    : GrDrawTarget(gpu->getContext())
    , fDstGpu(gpu)
    , fClipSet(true)
    , fClipProxyState(kUnknown_ClipProxyState)
    , fVertexPool(*vertexPool)
    , fIndexPool(*indexPool)
    , fFlushing(false) {

    fDstGpu->ref();
    fCaps.reset(SkRef(fDstGpu->caps()));

    GrAssert(NULL != vertexPool);
    GrAssert(NULL != indexPool);

    GeometryPoolState& poolState = fGeoPoolStateStack.push_back();
    poolState.fUsedPoolVertexBytes = 0;
    poolState.fUsedPoolIndexBytes = 0;
#if GR_DEBUG
    poolState.fPoolVertexBuffer = (GrVertexBuffer*)~0;
    poolState.fPoolStartVertex = ~0;
    poolState.fPoolIndexBuffer = (GrIndexBuffer*)~0;
    poolState.fPoolStartIndex = ~0;
#endif
    this->reset();
}

GrInOrderDrawBuffer::~GrInOrderDrawBuffer() {
    this->reset();
    // This must be called by before the GrDrawTarget destructor
    this->releaseGeometry();
    fDstGpu->unref();
}

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

namespace {
void get_vertex_bounds(const void* vertices,
                       size_t vertexSize,
                       int vertexCount,
                       SkRect* bounds) {
    GrAssert(vertexSize >= sizeof(GrPoint));
    GrAssert(vertexCount > 0);
    const GrPoint* point = static_cast<const GrPoint*>(vertices);
    bounds->fLeft = bounds->fRight = point->fX;
    bounds->fTop = bounds->fBottom = point->fY;
    for (int i = 1; i < vertexCount; ++i) {
        point = reinterpret_cast<GrPoint*>(reinterpret_cast<intptr_t>(point) + vertexSize);
        bounds->growToInclude(point->fX, point->fY);
    }
}
}

void GrInOrderDrawBuffer::onDrawRect(const GrRect& rect,
                                     const SkMatrix* matrix,
                                     const GrRect* localRect,
                                     const SkMatrix* localMatrix) {
    GrDrawState::AutoColorRestore acr;

    GrDrawState* drawState = this->drawState();

    GrColor color = drawState->getColor();
    GrVertexAttribArray<3> attribs;

    // set position attrib
    static const GrVertexAttrib kPosAttrib =
        {kVec2f_GrVertexAttribType, 0, kPosition_GrVertexAttribBinding};
    attribs.push_back(kPosAttrib);

    size_t currentOffset = sizeof(GrPoint);
    int colorOffset = -1;
    int localOffset = -1;

    // Using per-vertex colors allows batching across colors. (A lot of rects in a row differing
    // only in color is a common occurrence in tables). However, having per-vertex colors disables
    // blending optimizations because we don't know if the color will be solid or not. These
    // optimizations help determine whether coverage and color can be blended correctly when
    // dual-source blending isn't available. This comes into play when there is coverage. If colors
    // were a stage it could take a hint that every vertex's color will be opaque.
    if (this->caps()->dualSourceBlendingSupport() || drawState->hasSolidCoverage()) {
        colorOffset = currentOffset;
        GrVertexAttrib colorAttrib =
            {kVec4ub_GrVertexAttribType, currentOffset, kColor_GrVertexAttribBinding};
        attribs.push_back(colorAttrib);
        currentOffset += sizeof(GrColor);
        // We set the draw state's color to white here. This is done so that any batching performed
        // in our subclass's onDraw() won't get a false from GrDrawState::op== due to a color
        // mismatch. TODO: Once vertex layout is owned by GrDrawState it should skip comparing the
        // constant color in its op== when the kColor layout bit is set and then we can remove this.
        acr.set(drawState, 0xFFFFFFFF);
    }

    if (NULL != localRect) {
        localOffset = currentOffset;
        GrVertexAttrib localCoordAttrib =
            {kVec2f_GrVertexAttribType, currentOffset, kLocalCoord_GrVertexAttribBinding};
        attribs.push_back(localCoordAttrib);
        currentOffset += sizeof(GrPoint);
    }

    drawState->setVertexAttribs(attribs.begin(), attribs.count());
    AutoReleaseGeometry geo(this, 4, 0);
    if (!geo.succeeded()) {
        GrPrintf("Failed to get space for vertices!\n");
        return;
    }

    // Go to device coords to allow batching across matrix changes
    SkMatrix combinedMatrix;
    if (NULL != matrix) {
        combinedMatrix = *matrix;
    } else {
        combinedMatrix.reset();
    }
    combinedMatrix.postConcat(drawState->getViewMatrix());
    // When the caller has provided an explicit source rect for a stage then we don't want to
    // modify that stage's matrix. Otherwise if the effect is generating its source rect from
    // the vertex positions then we have to account for the view matrix change.
    GrDrawState::AutoDeviceCoordDraw adcd(drawState);
    if (!adcd.succeeded()) {
        return;
    }

    size_t vsize = drawState->getVertexSize();
    GrAssert(vsize == currentOffset);

    geo.positions()->setRectFan(rect.fLeft, rect.fTop, rect.fRight, rect.fBottom, vsize);
    combinedMatrix.mapPointsWithStride(geo.positions(), vsize, 4);

    SkRect devBounds;
    // since we already computed the dev verts, set the bounds hint. This will help us avoid
    // unnecessary clipping in our onDraw().
    get_vertex_bounds(geo.vertices(), vsize, 4, &devBounds);

    if (localOffset >= 0) {
        GrPoint* coords = GrTCast<GrPoint*>(GrTCast<intptr_t>(geo.vertices()) + localOffset);
        coords->setRectFan(localRect->fLeft, localRect->fTop,
                           localRect->fRight, localRect->fBottom,
                            vsize);
        if (NULL != localMatrix) {
            localMatrix->mapPointsWithStride(coords, vsize, 4);
        }
    }

    if (colorOffset >= 0) {
        GrColor* vertColor = GrTCast<GrColor*>(GrTCast<intptr_t>(geo.vertices()) + colorOffset);
        for (int i = 0; i < 4; ++i) {
            *vertColor = color;
            vertColor = (GrColor*) ((intptr_t) vertColor + vsize);
        }
    }

    this->setIndexSourceToBuffer(this->getContext()->getQuadIndexBuffer());
    this->drawIndexedInstances(kTriangles_GrPrimitiveType, 1, 4, 6, &devBounds);

    // to ensure that stashing the drawState ptr is valid
    GrAssert(this->drawState() == drawState);
}

bool GrInOrderDrawBuffer::quickInsideClip(const SkRect& devBounds) {
    if (!this->getDrawState().isClipState()) {
        return true;
    }
    if (kUnknown_ClipProxyState == fClipProxyState) {
        SkIRect rect;
        bool iior;
        this->getClip()->getConservativeBounds(this->getDrawState().getRenderTarget(), &rect, &iior);
        if (iior) {
            // The clip is a rect. We will remember that in fProxyClip. It is common for an edge (or
            // all edges) of the clip to be at the edge of the RT. However, we get that clipping for
            // free via the viewport. We don't want to think that clipping must be enabled in this
            // case. So we extend the clip outward from the edge to avoid these false negatives.
            fClipProxyState = kValid_ClipProxyState;
            fClipProxy = SkRect::MakeFromIRect(rect);

            if (fClipProxy.fLeft <= 0) {
                fClipProxy.fLeft = SK_ScalarMin;
            }
            if (fClipProxy.fTop <= 0) {
                fClipProxy.fTop = SK_ScalarMin;
            }
            if (fClipProxy.fRight >= this->getDrawState().getRenderTarget()->width()) {
                fClipProxy.fRight = SK_ScalarMax;
            }
            if (fClipProxy.fBottom >= this->getDrawState().getRenderTarget()->height()) {
                fClipProxy.fBottom = SK_ScalarMax;
            }
        } else {
            fClipProxyState = kInvalid_ClipProxyState;
        }
    }
    if (kValid_ClipProxyState == fClipProxyState) {
        return fClipProxy.contains(devBounds);
    }
    SkPoint originOffset = {SkIntToScalar(this->getClip()->fOrigin.fX),
                            SkIntToScalar(this->getClip()->fOrigin.fY)};
    SkRect clipSpaceBounds = devBounds;
    clipSpaceBounds.offset(originOffset);
    return this->getClip()->fClipStack->quickContains(clipSpaceBounds);
}

int GrInOrderDrawBuffer::concatInstancedDraw(const DrawInfo& info) {
    GrAssert(info.isInstanced());

    const GeometrySrcState& geomSrc = this->getGeomSrc();
    const GrDrawState& drawState = this->getDrawState();

    // we only attempt to concat the case when reserved verts are used with a client-specified index
    // buffer. To make this work with client-specified VBs we'd need to know if the VB was updated
    // between draws.
    if (kReserved_GeometrySrcType != geomSrc.fVertexSrc ||
        kBuffer_GeometrySrcType != geomSrc.fIndexSrc) {
        return 0;
    }
    // Check if there is a draw info that is compatible that uses the same VB from the pool and
    // the same IB
    if (kDraw_Cmd != fCmds.back()) {
        return 0;
    }

    DrawRecord* draw = &fDraws.back();
    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    const GrVertexBuffer* vertexBuffer = poolState.fPoolVertexBuffer;

    if (!draw->isInstanced() ||
        draw->verticesPerInstance() != info.verticesPerInstance() ||
        draw->indicesPerInstance() != info.indicesPerInstance() ||
        draw->fVertexBuffer != vertexBuffer ||
        draw->fIndexBuffer != geomSrc.fIndexBuffer) {
        return 0;
    }
    // info does not yet account for the offset from the start of the pool's VB while the previous
    // draw record does.
    int adjustedStartVertex = poolState.fPoolStartVertex + info.startVertex();
    if (draw->startVertex() + draw->vertexCount() != adjustedStartVertex) {
        return 0;
    }

    GrAssert(poolState.fPoolStartVertex == draw->startVertex() + draw->vertexCount());

    // how many instances can be concat'ed onto draw given the size of the index buffer
    int instancesToConcat = this->indexCountInCurrentSource() / info.indicesPerInstance();
    instancesToConcat -= draw->instanceCount();
    instancesToConcat = GrMin(instancesToConcat, info.instanceCount());

    // update the amount of reserved vertex data actually referenced in draws
    size_t vertexBytes = instancesToConcat * info.verticesPerInstance() *
                         drawState.getVertexSize();
    poolState.fUsedPoolVertexBytes = GrMax(poolState.fUsedPoolVertexBytes, vertexBytes);

    draw->adjustInstanceCount(instancesToConcat);
    return instancesToConcat;
}

class AutoClipReenable {
public:
    AutoClipReenable() : fDrawState(NULL) {}
    ~AutoClipReenable() {
        if (NULL != fDrawState) {
            fDrawState->enableState(GrDrawState::kClip_StateBit);
        }
    }
    void set(GrDrawState* drawState) {
        if (drawState->isClipState()) {
            fDrawState = drawState;
            drawState->disableState(GrDrawState::kClip_StateBit);
        }
    }
private:
    GrDrawState*    fDrawState;
};

void GrInOrderDrawBuffer::onDraw(const DrawInfo& info) {

    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    const GrDrawState& drawState = this->getDrawState();
    AutoClipReenable acr;

    if (drawState.isClipState() &&
        NULL != info.getDevBounds() &&
        this->quickInsideClip(*info.getDevBounds())) {
        acr.set(this->drawState());
    }

    if (this->needsNewClip()) {
       this->recordClip();
    }
    if (this->needsNewState()) {
        this->recordState();
    }

    DrawRecord* draw;
    if (info.isInstanced()) {
        int instancesConcated = this->concatInstancedDraw(info);
        if (info.instanceCount() > instancesConcated) {
            draw = this->recordDraw(info);
            draw->adjustInstanceCount(-instancesConcated);
        } else {
            return;
        }
    } else {
        draw = this->recordDraw(info);
    }

    switch (this->getGeomSrc().fVertexSrc) {
        case kBuffer_GeometrySrcType:
            draw->fVertexBuffer = this->getGeomSrc().fVertexBuffer;
            break;
        case kReserved_GeometrySrcType: // fallthrough
        case kArray_GeometrySrcType: {
            size_t vertexBytes = (info.vertexCount() + info.startVertex()) *
                                 drawState.getVertexSize();
            poolState.fUsedPoolVertexBytes = GrMax(poolState.fUsedPoolVertexBytes, vertexBytes);
            draw->fVertexBuffer = poolState.fPoolVertexBuffer;
            draw->adjustStartVertex(poolState.fPoolStartVertex);
            break;
        }
        default:
            GrCrash("unknown geom src type");
    }
    draw->fVertexBuffer->ref();

    if (info.isIndexed()) {
        switch (this->getGeomSrc().fIndexSrc) {
            case kBuffer_GeometrySrcType:
                draw->fIndexBuffer = this->getGeomSrc().fIndexBuffer;
                break;
            case kReserved_GeometrySrcType: // fallthrough
            case kArray_GeometrySrcType: {
                size_t indexBytes = (info.indexCount() + info.startIndex()) * sizeof(uint16_t);
                poolState.fUsedPoolIndexBytes = GrMax(poolState.fUsedPoolIndexBytes, indexBytes);
                draw->fIndexBuffer = poolState.fPoolIndexBuffer;
                draw->adjustStartIndex(poolState.fPoolStartIndex);
                break;
            }
            default:
                GrCrash("unknown geom src type");
        }
        draw->fIndexBuffer->ref();
    } else {
        draw->fIndexBuffer = NULL;
    }
}

GrInOrderDrawBuffer::StencilPath::StencilPath() : fStroke(SkStrokeRec::kFill_InitStyle) {}

void GrInOrderDrawBuffer::onStencilPath(const GrPath* path, const SkStrokeRec& stroke,
                                        SkPath::FillType fill) {
    if (this->needsNewClip()) {
        this->recordClip();
    }
    // Only compare the subset of GrDrawState relevant to path stenciling?
    if (this->needsNewState()) {
        this->recordState();
    }
    StencilPath* sp = this->recordStencilPath();
    sp->fPath.reset(path);
    path->ref();
    sp->fFill = fill;
    sp->fStroke = stroke;
}

void GrInOrderDrawBuffer::clear(const GrIRect* rect, GrColor color, GrRenderTarget* renderTarget) {
    GrIRect r;
    if (NULL == renderTarget) {
        renderTarget = this->drawState()->getRenderTarget();
        GrAssert(NULL != renderTarget);
    }
    if (NULL == rect) {
        // We could do something smart and remove previous draws and clears to
        // the current render target. If we get that smart we have to make sure
        // those draws aren't read before this clear (render-to-texture).
        r.setLTRB(0, 0, renderTarget->width(), renderTarget->height());
        rect = &r;
    }
    Clear* clr = this->recordClear();
    clr->fColor = color;
    clr->fRect = *rect;
    clr->fRenderTarget = renderTarget;
    renderTarget->ref();
}

void GrInOrderDrawBuffer::reset() {
    GrAssert(1 == fGeoPoolStateStack.count());
    this->resetVertexSource();
    this->resetIndexSource();
    int numDraws = fDraws.count();
    for (int d = 0; d < numDraws; ++d) {
        // we always have a VB, but not always an IB
        GrAssert(NULL != fDraws[d].fVertexBuffer);
        fDraws[d].fVertexBuffer->unref();
        GrSafeUnref(fDraws[d].fIndexBuffer);
    }
    fCmds.reset();
    fDraws.reset();
    fStencilPaths.reset();
    fStates.reset();
    fClears.reset();
    fVertexPool.reset();
    fIndexPool.reset();
    fClips.reset();
    fClipOrigins.reset();
    fCopySurfaces.reset();
    fClipSet = true;
}

bool GrInOrderDrawBuffer::flush() {
    GrAssert(kReserved_GeometrySrcType != this->getGeomSrc().fVertexSrc);
    GrAssert(kReserved_GeometrySrcType != this->getGeomSrc().fIndexSrc);

    int numCmds = fCmds.count();
    if (0 == numCmds) {
        return false;
    }
    GrAssert(!fFlushing);

    GrAutoTRestore<bool> flushRestore(&fFlushing);
    fFlushing = true;

    fVertexPool.unlock();
    fIndexPool.unlock();

    GrDrawTarget::AutoClipRestore acr(fDstGpu);
    AutoGeometryAndStatePush agasp(fDstGpu, kPreserve_ASRInit);

    GrDrawState playbackState;
    GrDrawState* prevDrawState = fDstGpu->drawState();
    prevDrawState->ref();
    fDstGpu->setDrawState(&playbackState);

    GrClipData clipData;

    int currState       = 0;
    int currClip        = 0;
    int currClear       = 0;
    int currDraw        = 0;
    int currStencilPath = 0;
    int currCopySurface = 0;

    for (int c = 0; c < numCmds; ++c) {
        switch (fCmds[c]) {
            case kDraw_Cmd: {
                const DrawRecord& draw = fDraws[currDraw];
                fDstGpu->setVertexSourceToBuffer(draw.fVertexBuffer);
                if (draw.isIndexed()) {
                    fDstGpu->setIndexSourceToBuffer(draw.fIndexBuffer);
                }
                fDstGpu->executeDraw(draw);

                ++currDraw;
                break;
            }
            case kStencilPath_Cmd: {
                const StencilPath& sp = fStencilPaths[currStencilPath];
                fDstGpu->stencilPath(sp.fPath.get(), sp.fStroke, sp.fFill);
                ++currStencilPath;
                break;
            }
            case kSetState_Cmd:
                fStates[currState].restoreTo(&playbackState);
                ++currState;
                break;
            case kSetClip_Cmd:
                clipData.fClipStack = &fClips[currClip];
                clipData.fOrigin = fClipOrigins[currClip];
                fDstGpu->setClip(&clipData);
                ++currClip;
                break;
            case kClear_Cmd:
                fDstGpu->clear(&fClears[currClear].fRect,
                               fClears[currClear].fColor,
                               fClears[currClear].fRenderTarget);
                ++currClear;
                break;
            case kCopySurface_Cmd:
                fDstGpu->copySurface(fCopySurfaces[currCopySurface].fDst.get(),
                                     fCopySurfaces[currCopySurface].fSrc.get(),
                                     fCopySurfaces[currCopySurface].fSrcRect,
                                     fCopySurfaces[currCopySurface].fDstPoint);
                ++currCopySurface;
                break;
        }
    }
    // we should have consumed all the states, clips, etc.
    GrAssert(fStates.count() == currState);
    GrAssert(fClips.count() == currClip);
    GrAssert(fClipOrigins.count() == currClip);
    GrAssert(fClears.count() == currClear);
    GrAssert(fDraws.count()  == currDraw);
    GrAssert(fCopySurfaces.count() == currCopySurface);

    fDstGpu->setDrawState(prevDrawState);
    prevDrawState->unref();
    this->reset();
    return true;
}

bool GrInOrderDrawBuffer::onCopySurface(GrSurface* dst,
                                        GrSurface* src,
                                        const SkIRect& srcRect,
                                        const SkIPoint& dstPoint) {
    if (fDstGpu->canCopySurface(dst, src, srcRect, dstPoint)) {
        CopySurface* cs = this->recordCopySurface();
        cs->fDst.reset(SkRef(dst));
        cs->fSrc.reset(SkRef(src));
        cs->fSrcRect = srcRect;
        cs->fDstPoint = dstPoint;
        return true;
    } else {
        return false;
    }
}

bool GrInOrderDrawBuffer::onCanCopySurface(GrSurface* dst,
                                           GrSurface* src,
                                           const SkIRect& srcRect,
                                           const SkIPoint& dstPoint) {
    return fDstGpu->canCopySurface(dst, src, srcRect, dstPoint);
}

void GrInOrderDrawBuffer::initCopySurfaceDstDesc(const GrSurface* src, GrTextureDesc* desc) {
    fDstGpu->initCopySurfaceDstDesc(src, desc);
}

void GrInOrderDrawBuffer::willReserveVertexAndIndexSpace(
                                int vertexCount,
                                int indexCount) {
    // We use geometryHints() to know whether to flush the draw buffer. We
    // can't flush if we are inside an unbalanced pushGeometrySource.
    // Moreover, flushing blows away vertex and index data that was
    // previously reserved. So if the vertex or index data is pulled from
    // reserved space and won't be released by this request then we can't
    // flush.
    bool insideGeoPush = fGeoPoolStateStack.count() > 1;

    bool unreleasedVertexSpace =
        !vertexCount &&
        kReserved_GeometrySrcType == this->getGeomSrc().fVertexSrc;

    bool unreleasedIndexSpace =
        !indexCount &&
        kReserved_GeometrySrcType == this->getGeomSrc().fIndexSrc;

    // we don't want to finalize any reserved geom on the target since
    // we don't know that the client has finished writing to it.
    bool targetHasReservedGeom = fDstGpu->hasReservedVerticesOrIndices();

    int vcount = vertexCount;
    int icount = indexCount;

    if (!insideGeoPush &&
        !unreleasedVertexSpace &&
        !unreleasedIndexSpace &&
        !targetHasReservedGeom &&
        this->geometryHints(&vcount, &icount)) {

        this->flush();
    }
}

bool GrInOrderDrawBuffer::geometryHints(int* vertexCount,
                                        int* indexCount) const {
    // we will recommend a flush if the data could fit in a single
    // preallocated buffer but none are left and it can't fit
    // in the current buffer (which may not be prealloced).
    bool flush = false;
    if (NULL != indexCount) {
        int32_t currIndices = fIndexPool.currentBufferIndices();
        if (*indexCount > currIndices &&
            (!fIndexPool.preallocatedBuffersRemaining() &&
             *indexCount <= fIndexPool.preallocatedBufferIndices())) {

            flush = true;
        }
        *indexCount = currIndices;
    }
    if (NULL != vertexCount) {
        size_t vertexSize = this->getDrawState().getVertexSize();
        int32_t currVertices = fVertexPool.currentBufferVertices(vertexSize);
        if (*vertexCount > currVertices &&
            (!fVertexPool.preallocatedBuffersRemaining() &&
             *vertexCount <= fVertexPool.preallocatedBufferVertices(vertexSize))) {

            flush = true;
        }
        *vertexCount = currVertices;
    }
    return flush;
}

bool GrInOrderDrawBuffer::onReserveVertexSpace(size_t vertexSize,
                                               int vertexCount,
                                               void** vertices) {
    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    GrAssert(vertexCount > 0);
    GrAssert(NULL != vertices);
    GrAssert(0 == poolState.fUsedPoolVertexBytes);

    *vertices = fVertexPool.makeSpace(vertexSize,
                                      vertexCount,
                                      &poolState.fPoolVertexBuffer,
                                      &poolState.fPoolStartVertex);
    return NULL != *vertices;
}

bool GrInOrderDrawBuffer::onReserveIndexSpace(int indexCount, void** indices) {
    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    GrAssert(indexCount > 0);
    GrAssert(NULL != indices);
    GrAssert(0 == poolState.fUsedPoolIndexBytes);

    *indices = fIndexPool.makeSpace(indexCount,
                                    &poolState.fPoolIndexBuffer,
                                    &poolState.fPoolStartIndex);
    return NULL != *indices;
}

void GrInOrderDrawBuffer::releaseReservedVertexSpace() {
    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    const GeometrySrcState& geoSrc = this->getGeomSrc();

    // If we get a release vertex space call then our current source should either be reserved
    // or array (which we copied into reserved space).
    GrAssert(kReserved_GeometrySrcType == geoSrc.fVertexSrc ||
             kArray_GeometrySrcType == geoSrc.fVertexSrc);

    // When the caller reserved vertex buffer space we gave it back a pointer
    // provided by the vertex buffer pool. At each draw we tracked the largest
    // offset into the pool's pointer that was referenced. Now we return to the
    // pool any portion at the tail of the allocation that no draw referenced.
    size_t reservedVertexBytes = geoSrc.fVertexSize * geoSrc.fVertexCount;
    fVertexPool.putBack(reservedVertexBytes -
                        poolState.fUsedPoolVertexBytes);
    poolState.fUsedPoolVertexBytes = 0;
    poolState.fPoolVertexBuffer = NULL;
    poolState.fPoolStartVertex = 0;
}

void GrInOrderDrawBuffer::releaseReservedIndexSpace() {
    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    const GeometrySrcState& geoSrc = this->getGeomSrc();

    // If we get a release index space call then our current source should either be reserved
    // or array (which we copied into reserved space).
    GrAssert(kReserved_GeometrySrcType == geoSrc.fIndexSrc ||
             kArray_GeometrySrcType == geoSrc.fIndexSrc);

    // Similar to releaseReservedVertexSpace we return any unused portion at
    // the tail
    size_t reservedIndexBytes = sizeof(uint16_t) * geoSrc.fIndexCount;
    fIndexPool.putBack(reservedIndexBytes - poolState.fUsedPoolIndexBytes);
    poolState.fUsedPoolIndexBytes = 0;
    poolState.fPoolIndexBuffer = NULL;
    poolState.fPoolStartIndex = 0;
}

void GrInOrderDrawBuffer::onSetVertexSourceToArray(const void* vertexArray,
                                                   int vertexCount) {

    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    GrAssert(0 == poolState.fUsedPoolVertexBytes);
#if GR_DEBUG
    bool success =
#endif
    fVertexPool.appendVertices(this->getVertexSize(),
                               vertexCount,
                               vertexArray,
                               &poolState.fPoolVertexBuffer,
                               &poolState.fPoolStartVertex);
    GR_DEBUGASSERT(success);
}

void GrInOrderDrawBuffer::onSetIndexSourceToArray(const void* indexArray,
                                                  int indexCount) {
    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    GrAssert(0 == poolState.fUsedPoolIndexBytes);
#if GR_DEBUG
    bool success =
#endif
    fIndexPool.appendIndices(indexCount,
                             indexArray,
                             &poolState.fPoolIndexBuffer,
                             &poolState.fPoolStartIndex);
    GR_DEBUGASSERT(success);
}

void GrInOrderDrawBuffer::releaseVertexArray() {
    // When the client provides an array as the vertex source we handled it
    // by copying their array into reserved space.
    this->GrInOrderDrawBuffer::releaseReservedVertexSpace();
}

void GrInOrderDrawBuffer::releaseIndexArray() {
    // When the client provides an array as the index source we handled it
    // by copying their array into reserved space.
    this->GrInOrderDrawBuffer::releaseReservedIndexSpace();
}

void GrInOrderDrawBuffer::geometrySourceWillPush() {
    GeometryPoolState& poolState = fGeoPoolStateStack.push_back();
    poolState.fUsedPoolVertexBytes = 0;
    poolState.fUsedPoolIndexBytes = 0;
#if GR_DEBUG
    poolState.fPoolVertexBuffer = (GrVertexBuffer*)~0;
    poolState.fPoolStartVertex = ~0;
    poolState.fPoolIndexBuffer = (GrIndexBuffer*)~0;
    poolState.fPoolStartIndex = ~0;
#endif
}

void GrInOrderDrawBuffer::geometrySourceWillPop(
                                        const GeometrySrcState& restoredState) {
    GrAssert(fGeoPoolStateStack.count() > 1);
    fGeoPoolStateStack.pop_back();
    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    // we have to assume that any slack we had in our vertex/index data
    // is now unreleasable because data may have been appended later in the
    // pool.
    if (kReserved_GeometrySrcType == restoredState.fVertexSrc ||
        kArray_GeometrySrcType == restoredState.fVertexSrc) {
        poolState.fUsedPoolVertexBytes = restoredState.fVertexSize * restoredState.fVertexCount;
    }
    if (kReserved_GeometrySrcType == restoredState.fIndexSrc ||
        kArray_GeometrySrcType == restoredState.fIndexSrc) {
        poolState.fUsedPoolIndexBytes = sizeof(uint16_t) *
                                         restoredState.fIndexCount;
    }
}

bool GrInOrderDrawBuffer::needsNewState() const {
    return fStates.empty() || !fStates.back().isEqual(this->getDrawState());
}

bool GrInOrderDrawBuffer::needsNewClip() const {
    GrAssert(fClips.count() == fClipOrigins.count());
    if (this->getDrawState().isClipState()) {
       if (fClipSet &&
           (fClips.empty() ||
            fClips.back() != *this->getClip()->fClipStack ||
            fClipOrigins.back() != this->getClip()->fOrigin)) {
           return true;
       }
    }
    return false;
}

void GrInOrderDrawBuffer::recordClip() {
    fClips.push_back() = *this->getClip()->fClipStack;
    fClipOrigins.push_back() = this->getClip()->fOrigin;
    fClipSet = false;
    fCmds.push_back(kSetClip_Cmd);
}

void GrInOrderDrawBuffer::recordState() {
    fStates.push_back().saveFrom(this->getDrawState());
    fCmds.push_back(kSetState_Cmd);
}

GrInOrderDrawBuffer::DrawRecord* GrInOrderDrawBuffer::recordDraw(const DrawInfo& info) {
    fCmds.push_back(kDraw_Cmd);
    return &fDraws.push_back(info);
}

GrInOrderDrawBuffer::StencilPath* GrInOrderDrawBuffer::recordStencilPath() {
    fCmds.push_back(kStencilPath_Cmd);
    return &fStencilPaths.push_back();
}

GrInOrderDrawBuffer::Clear* GrInOrderDrawBuffer::recordClear() {
    fCmds.push_back(kClear_Cmd);
    return &fClears.push_back();
}

GrInOrderDrawBuffer::CopySurface* GrInOrderDrawBuffer::recordCopySurface() {
    fCmds.push_back(kCopySurface_Cmd);
    return &fCopySurfaces.push_back();
}


void GrInOrderDrawBuffer::clipWillBeSet(const GrClipData* newClipData) {
    INHERITED::clipWillBeSet(newClipData);
    fClipSet = true;
    fClipProxyState = kUnknown_ClipProxyState;
}