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 "GrGpu.h"
#include "GrIndexBuffer.h"
#include "GrPath.h"
#include "GrRenderTarget.h"
#include "GrTexture.h"
#include "GrVertexBuffer.h"

GrInOrderDrawBuffer::GrInOrderDrawBuffer(const GrGpu* gpu,
                                         GrVertexBufferAllocPool* vertexPool,
                                         GrIndexBufferAllocPool* indexPool)
    : fAutoFlushTarget(NULL)
    , fClipSet(true)
    , fVertexPool(*vertexPool)
    , fIndexPool(*indexPool)
    , fLastRectVertexLayout(0)
    , fQuadIndexBuffer(NULL)
    , fMaxQuads(0)
    , fFlushing(false) {

    fCaps = gpu->getCaps();

    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();
    GrSafeUnref(fQuadIndexBuffer);
    GrSafeUnref(fAutoFlushTarget);
}

void GrInOrderDrawBuffer::setQuadIndexBuffer(const GrIndexBuffer* indexBuffer) {
    bool newIdxBuffer = fQuadIndexBuffer != indexBuffer;
    if (newIdxBuffer) {
        GrSafeUnref(fQuadIndexBuffer);
        fQuadIndexBuffer = indexBuffer;
        GrSafeRef(fQuadIndexBuffer);
        fCurrQuad = 0;
        fMaxQuads = (NULL == indexBuffer) ? 0 : indexBuffer->maxQuads();
    } else {
        GrAssert((NULL == indexBuffer && 0 == fMaxQuads) ||
                 (indexBuffer->maxQuads() == fMaxQuads));
    }
}

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

void GrInOrderDrawBuffer::resetDrawTracking() {
    fCurrQuad = 0;
    fInstancedDrawTracker.reset();
}

void GrInOrderDrawBuffer::drawRect(const GrRect& rect,
                                   const GrMatrix* matrix,
                                   const GrRect* srcRects[],
                                   const GrMatrix* srcMatrices[]) {

    GrAssert(!(NULL == fQuadIndexBuffer && fCurrQuad));
    GrAssert(!(fDraws.empty() && fCurrQuad));
    GrAssert(!(0 != fMaxQuads && NULL == fQuadIndexBuffer));

    GrDrawState* drawState = this->drawState();

    // if we have a quad IB then either append to the previous run of
    // rects or start a new run
    if (fMaxQuads) {

        bool appendToPreviousDraw = false;
        GrVertexLayout layout = GetRectVertexLayout(srcRects);

        // When we batch rects we store the color at each vertex in order
        // to allow batching when only the draw color is changing (the usual case)
        layout |= kColor_VertexLayoutBit;

        AutoReleaseGeometry geo(this, layout, 4, 0);
        if (!geo.succeeded()) {
            GrPrintf("Failed to get space for vertices!\n");
            return;
        }
        GrMatrix combinedMatrix = drawState->getViewMatrix();
        // We go to device space so that matrix changes allow us to concat
        // rect draws. When the caller has provided explicit source rects
        // then we don't want to modify the sampler matrices. Otherwise
        // we have to account for the view matrix change in the sampler
        // matrices.
        uint32_t explicitCoordMask = 0;
        if (srcRects) {
            for (int s = 0; s < GrDrawState::kNumStages; ++s) {
                if (srcRects[s]) {
                    explicitCoordMask |= (1 << s);
                }
            }
        }
        GrDrawState::AutoDeviceCoordDraw adcd(this->drawState(), explicitCoordMask);
        if (!adcd.succeeded()) {
            return;
        }
        if (NULL != matrix) {
            combinedMatrix.preConcat(*matrix);
        }

        SetRectVertices(rect, &combinedMatrix, srcRects, srcMatrices,
                        this->getDrawState().getColor(), layout, geo.vertices());

        // Now that the paint's color is stored in the vertices set it to
        // white so that the following code can batch all the rects regardless
        // of paint color
        GrDrawState::AutoColorRestore acr(this->drawState(), SK_ColorWHITE);

        // we don't want to miss an opportunity to batch rects together
        // simply because the clip has changed if the clip doesn't affect
        // the rect.
        bool disabledClip = false;

        if (drawState->isClipState()) {

            GrRect devClipRect;
            bool isIntersectionOfRects = false;

            fClip->fClipStack->getConservativeBounds(-fClip->fOrigin.fX,
                                                     -fClip->fOrigin.fY,
                                                     drawState->getRenderTarget()->width(),
                                                     drawState->getRenderTarget()->height(),
                                                     &devClipRect,
                                                     &isIntersectionOfRects);

            if (isIntersectionOfRects) {
                // If the clip rect touches the edge of the viewport, extended it
                // out (close) to infinity to avoid bogus intersections.
                // We might consider a more exact clip to viewport if this
                // conservative test fails.
                const GrRenderTarget* target = drawState->getRenderTarget();
                if (0 >= devClipRect.fLeft) {
                    devClipRect.fLeft = GR_ScalarMin;
                }
                if (target->width() <= devClipRect.fRight) {
                    devClipRect.fRight = GR_ScalarMax;
                }
                if (0 >= devClipRect.top()) {
                    devClipRect.fTop = GR_ScalarMin;
                }
                if (target->height() <= devClipRect.fBottom) {
                    devClipRect.fBottom = GR_ScalarMax;
                }
                int stride = VertexSize(layout);
                bool insideClip = true;
                for (int v = 0; v < 4; ++v) {
                    const GrPoint& p = *GetVertexPoint(geo.vertices(), v, stride);
                    if (!devClipRect.contains(p)) {
                        insideClip = false;
                        break;
                    }
                }
                if (insideClip) {
                    drawState->disableState(GrDrawState::kClip_StateBit);
                    disabledClip = true;
                }
            }
        }

        if (!this->needsNewClip() &&
            !this->needsNewState() &&
            fCurrQuad > 0 &&
            fCurrQuad < fMaxQuads &&
            layout == fLastRectVertexLayout) {

            int vsize = VertexSize(layout);

            Draw& lastDraw = fDraws.back();

            GrAssert(lastDraw.fIndexBuffer == fQuadIndexBuffer);
            GrAssert(kTriangles_GrPrimitiveType == lastDraw.fPrimitiveType);
            GrAssert(0 == lastDraw.fVertexCount % 4);
            GrAssert(0 == lastDraw.fIndexCount % 6);
            GrAssert(0 == lastDraw.fStartIndex);

            GeometryPoolState& poolState = fGeoPoolStateStack.back();

            appendToPreviousDraw =
                kDraw_Cmd == fCmds.back() &&
                lastDraw.fVertexBuffer == poolState.fPoolVertexBuffer &&
                (fCurrQuad * 4 + lastDraw.fStartVertex) == poolState.fPoolStartVertex;

            if (appendToPreviousDraw) {
                lastDraw.fVertexCount += 4;
                lastDraw.fIndexCount += 6;
                fCurrQuad += 1;
                // we reserved above, so we should be the first
                // use of this vertex reservation.
                GrAssert(0 == poolState.fUsedPoolVertexBytes);
                poolState.fUsedPoolVertexBytes = 4 * vsize;
            }
        }
        if (!appendToPreviousDraw) {
            this->setIndexSourceToBuffer(fQuadIndexBuffer);
            this->drawIndexed(kTriangles_GrPrimitiveType, 0, 0, 4, 6);
            fCurrQuad = 1;
            fLastRectVertexLayout = layout;
        }
        if (disabledClip) {
            drawState->enableState(GrDrawState::kClip_StateBit);
        }
        fInstancedDrawTracker.reset();
    } else {
        INHERITED::drawRect(rect, matrix, srcRects, srcMatrices);
    }
}

void GrInOrderDrawBuffer::drawIndexedInstances(GrPrimitiveType type,
                                               int instanceCount,
                                               int verticesPerInstance,
                                               int indicesPerInstance) {
    if (!verticesPerInstance || !indicesPerInstance) {
        return;
    }

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

    // we only attempt to concat the case when reserved verts are used with
    // an index buffer.
    if (kReserved_GeometrySrcType == geomSrc.fVertexSrc &&
        kBuffer_GeometrySrcType == geomSrc.fIndexSrc) {

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

        Draw* draw = NULL;
        // if the last draw used the same indices/vertices per shape then we
        // may be able to append to it.
        if (kDraw_Cmd == fCmds.back() &&
            verticesPerInstance == fInstancedDrawTracker.fVerticesPerInstance &&
            indicesPerInstance == fInstancedDrawTracker.fIndicesPerInstance) {
            GrAssert(fDraws.count());
            draw = &fDraws.back();
        }

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

        // Check whether the draw is compatible with this draw in order to
        // append
        if (NULL == draw ||
            draw->fIndexBuffer != geomSrc.fIndexBuffer ||
            draw->fPrimitiveType != type ||
            draw->fVertexBuffer != vertexBuffer) {

            draw = this->recordDraw();
            draw->fIndexBuffer = geomSrc.fIndexBuffer;
            geomSrc.fIndexBuffer->ref();
            draw->fVertexBuffer = vertexBuffer;
            vertexBuffer->ref();
            draw->fPrimitiveType = type;
            draw->fStartIndex = 0;
            draw->fIndexCount = 0;
            draw->fStartVertex = poolState.fPoolStartVertex;
            draw->fVertexCount = 0;
            draw->fVertexLayout = geomSrc.fVertexLayout;
        } else {
            GrAssert(!(draw->fIndexCount % indicesPerInstance));
            GrAssert(!(draw->fVertexCount % verticesPerInstance));
            GrAssert(poolState.fPoolStartVertex == draw->fStartVertex +
                                                   draw->fVertexCount);
        }

        // how many instances can be in a single draw
        int maxInstancesPerDraw = this->indexCountInCurrentSource() /
                                  indicesPerInstance;
        if (!maxInstancesPerDraw) {
            return;
        }
        // how many instances should be concat'ed onto draw
        int instancesToConcat = maxInstancesPerDraw - draw->fVertexCount /
                                                      verticesPerInstance;
        if (maxInstancesPerDraw > instanceCount) {
            maxInstancesPerDraw = instanceCount;
            if (instancesToConcat > instanceCount) {
                instancesToConcat = instanceCount;
            }
        }

        // update the amount of reserved data actually referenced in draws
        size_t vertexBytes = instanceCount * verticesPerInstance *
                             VertexSize(draw->fVertexLayout);
        poolState.fUsedPoolVertexBytes =
                            GrMax(poolState.fUsedPoolVertexBytes, vertexBytes);

        while (instanceCount) {
            if (!instancesToConcat) {
                int startVertex = draw->fStartVertex + draw->fVertexCount;
                draw = this->recordDraw();
                draw->fIndexBuffer = geomSrc.fIndexBuffer;
                geomSrc.fIndexBuffer->ref();
                draw->fVertexBuffer = vertexBuffer;
                vertexBuffer->ref();
                draw->fPrimitiveType = type;
                draw->fStartIndex = 0;
                draw->fStartVertex = startVertex;
                draw->fVertexCount = 0;
                draw->fVertexLayout = geomSrc.fVertexLayout;
                instancesToConcat = maxInstancesPerDraw;
            }
            draw->fVertexCount += instancesToConcat * verticesPerInstance;
            draw->fIndexCount += instancesToConcat * indicesPerInstance;
            instanceCount -= instancesToConcat;
            instancesToConcat = 0;
        }

        // update draw tracking for next draw
        fCurrQuad = 0;
        fInstancedDrawTracker.fVerticesPerInstance = verticesPerInstance;
        fInstancedDrawTracker.fIndicesPerInstance = indicesPerInstance;
    } else {
        this->INHERITED::drawIndexedInstances(type,
                                              instanceCount,
                                              verticesPerInstance,
                                              indicesPerInstance);
    }

}

void GrInOrderDrawBuffer::onDrawIndexed(GrPrimitiveType primitiveType,
                                        int startVertex,
                                        int startIndex,
                                        int vertexCount,
                                        int indexCount) {

    if (!vertexCount || !indexCount) {
        return;
    }

    this->resetDrawTracking();

    GeometryPoolState& poolState = fGeoPoolStateStack.back();

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

    Draw* draw = this->recordDraw();

    draw->fPrimitiveType = primitiveType;
    draw->fStartVertex   = startVertex;
    draw->fStartIndex    = startIndex;
    draw->fVertexCount   = vertexCount;
    draw->fIndexCount    = indexCount;

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

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

void GrInOrderDrawBuffer::onDrawNonIndexed(GrPrimitiveType primitiveType,
                                           int startVertex,
                                           int vertexCount) {
    if (!vertexCount) {
        return;
    }

    this->resetDrawTracking();

    GeometryPoolState& poolState = fGeoPoolStateStack.back();
    if (this->needsNewClip()) {
        this->recordClip();
    }
    if (this->needsNewState()) {
        this->recordState();
    }

    Draw* draw = this->recordDraw();
    draw->fPrimitiveType = primitiveType;
    draw->fStartVertex   = startVertex;
    draw->fStartIndex    = 0;
    draw->fVertexCount   = vertexCount;
    draw->fIndexCount    = 0;

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

void GrInOrderDrawBuffer::onStencilPath(const GrPath* path, GrPathFill 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;
}

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();
    fClipSet = true;

    this->resetDrawTracking();

    // we start off with a default clip and state so that we don't have
    // to do count checks on fClips, fStates, or fCmds before checking their
    // last entry.
    this->recordDefaultState();
    this->recordDefaultClip();
}

bool GrInOrderDrawBuffer::playback(GrDrawTarget* target) {
    GrAssert(kReserved_GeometrySrcType != this->getGeomSrc().fVertexSrc);
    GrAssert(kReserved_GeometrySrcType != this->getGeomSrc().fIndexSrc);

    GrAssert(NULL != target);
    GrAssert(target != this); // not considered and why?

    int numCmds = fCmds.count();
    GrAssert(numCmds >= 2);
    if (2 == numCmds) {
        GrAssert(kSetState_Cmd == fCmds[0]);
        GrAssert(kSetClip_Cmd  == fCmds[1]);
        return false;
    }

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

    GrDrawTarget::AutoClipRestore acr(target);
    AutoGeometryPush agp(target);
    GrDrawState* prevDrawState = target->drawState();
    prevDrawState->ref();

    GrClipData clipData;

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

    for (int c = 0; c < numCmds; ++c) {
        switch (fCmds[c]) {
            case kDraw_Cmd: {
                const Draw& draw = fDraws[currDraw];
                target->setVertexSourceToBuffer(draw.fVertexLayout, draw.fVertexBuffer);
                if (draw.fIndexCount) {
                    target->setIndexSourceToBuffer(draw.fIndexBuffer);
                }

                if (draw.fIndexCount) {
                    target->drawIndexed(draw.fPrimitiveType,
                                        draw.fStartVertex,
                                        draw.fStartIndex,
                                        draw.fVertexCount,
                                        draw.fIndexCount);
                } else {
                    target->drawNonIndexed(draw.fPrimitiveType,
                                           draw.fStartVertex,
                                           draw.fVertexCount);
                }
                ++currDraw;
                break;
            }
            case kStencilPath_Cmd: {
                const StencilPath& sp = fStencilPaths[currStencilPath];
                target->stencilPath(sp.fPath.get(), sp.fFill);
                ++currStencilPath;
                break;
            }
            case kSetState_Cmd:
                target->setDrawState(&fStates[currState]);
                ++currState;
                break;
            case kSetClip_Cmd:
                clipData.fClipStack = &fClips[currClip];
                clipData.fOrigin = fClipOrigins[currClip];
                target->setClip(&clipData);
                ++currClip;
                break;
            case kClear_Cmd:
                target->clear(&fClears[currClear].fRect,
                              fClears[currClear].fColor,
                              fClears[currClear].fRenderTarget);
                ++currClear;
                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);

    target->setDrawState(prevDrawState);
    prevDrawState->unref();
    return true;
}

void GrInOrderDrawBuffer::setAutoFlushTarget(GrDrawTarget* target) {
    GrSafeAssign(fAutoFlushTarget, target);
}

void GrInOrderDrawBuffer::willReserveVertexAndIndexSpace(
                                GrVertexLayout vertexLayout,
                                int vertexCount,
                                int indexCount) {
    if (NULL != fAutoFlushTarget) {
        // 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 =
            fAutoFlushTarget->hasReservedVerticesOrIndices();

        int vcount = vertexCount;
        int icount = indexCount;

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

            this->flushTo(fAutoFlushTarget);
        }
    }
}

bool GrInOrderDrawBuffer::geometryHints(GrVertexLayout vertexLayout,
                                        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) {
        int32_t currVertices = fVertexPool.currentBufferVertices(vertexLayout);
        if (*vertexCount > currVertices &&
            (!fVertexPool.preallocatedBuffersRemaining() &&
             *vertexCount <= fVertexPool.preallocatedBufferVertices(vertexLayout))) {

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

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

    *vertices = fVertexPool.makeSpace(vertexLayout,
                                      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 = VertexSize(geoSrc.fVertexLayout) *
                                 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->getVertexLayout(),
                               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;
    this->resetDrawTracking();
#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 =
            VertexSize(restoredState.fVertexLayout) *
            restoredState.fVertexCount;
    }
    if (kReserved_GeometrySrcType == restoredState.fIndexSrc ||
        kArray_GeometrySrcType == restoredState.fIndexSrc) {
        poolState.fUsedPoolIndexBytes = sizeof(uint16_t) *
                                         restoredState.fIndexCount;
    }
    this->resetDrawTracking();
}

bool GrInOrderDrawBuffer::needsNewState() const {
    // we should have recorded a default state in reset()
    GrAssert(!fStates.empty());
    return fStates.back() != this->getDrawState();
}

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

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

void GrInOrderDrawBuffer::recordDefaultClip() {
    fClips.push_back() = SkClipStack();
    fClipOrigins.push_back() = SkIPoint::Make(0, 0);
    fCmds.push_back(kSetClip_Cmd);
}

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

void GrInOrderDrawBuffer::recordDefaultState() {
    fStates.push_back(GrDrawState());
    fCmds.push_back(kSetState_Cmd);
}

GrInOrderDrawBuffer::Draw* GrInOrderDrawBuffer::recordDraw() {
    fCmds.push_back(kDraw_Cmd);
    return &fDraws.push_back();
}

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();
}

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