Add postFlush call to GrOnFlushCallbackObject

Adds a new postFlush method and renames the class to
GrOnFlushCallbackObject. Also removes the ref counting in favor of
making the callback object a purely virtual interface. ref/unref on the
callback interface would conflict with existing ref/unref methods on the
subclass. It is now the caller’s responsibility to ensure the lifetime
of the callback is tied to that of the context.

Bug: skia:
Change-Id: I2fc1f98c700032e296a36f3a9a09c0753ab47aea
Reviewed-on: https://skia-review.googlesource.com/15463
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 618 insertions, 0 deletions

diff --git a/tests/OnFlushCallbackTest.cpp b/tests/OnFlushCallbackTest.cpp
new file mode 100644
index 0000000000..4adcad93c6
--- /dev/null
+++ b/tests/OnFlushCallbackTest.cpp
@@ -0,0 +1,618 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "Test.h"
+
+#if SK_SUPPORT_GPU
+
+#include "GrClip.h"
+#include "GrContextPriv.h"
+#include "GrDefaultGeoProcFactory.h"
+#include "GrOnFlushResourceProvider.h"
+#include "GrRenderTargetContextPriv.h"
+#include "GrResourceProvider.h"
+#include "GrQuad.h"
+#include "effects/GrSimpleTextureEffect.h"
+#include "ops/GrTestMeshDrawOp.h"
+
+// This is a simplified mesh drawing op that can be used in the atlas generation test.
+// Please see AtlasedRectOp below.
+class NonAARectOp : public GrLegacyMeshDrawOp {
+public:
+    DEFINE_OP_CLASS_ID
+    const char* name() const override { return "NonAARectOp"; }
+
+    // This creates an instance of a simple non-AA solid color rect-drawing Op
+    static std::unique_ptr<GrDrawOp> Make(const SkRect& r, GrColor color) {
+        return std::unique_ptr<GrDrawOp>(new NonAARectOp(ClassID(), r, color));
+    }
+
+    // This creates an instance of a simple non-AA textured rect-drawing Op
+    static std::unique_ptr<GrDrawOp> Make(const SkRect& r, GrColor color, const SkRect& local) {
+        return std::unique_ptr<GrDrawOp>(new NonAARectOp(ClassID(), r, color, local));
+    }
+
+    GrColor color() const { return fColor; }
+
+protected:
+    NonAARectOp(uint32_t classID, const SkRect& r, GrColor color)
+        : INHERITED(classID)
+        , fColor(color)
+        , fHasLocalRect(false)
+        , fRect(r) {
+        // Choose some conservative values for aa bloat and zero area.
+        this->setBounds(r, HasAABloat::kYes, IsZeroArea::kYes);
+    }
+
+    NonAARectOp(uint32_t classID, const SkRect& r, GrColor color, const SkRect& local)
+        : INHERITED(classID)
+        , fColor(color)
+        , fHasLocalRect(true)
+        , fLocalQuad(local)
+        , fRect(r) {
+        // Choose some conservative values for aa bloat and zero area.
+        this->setBounds(r, HasAABloat::kYes, IsZeroArea::kYes);
+    }
+
+    GrColor fColor;
+    bool    fHasLocalRect;
+    GrQuad  fLocalQuad;
+    SkRect  fRect;
+
+private:
+    void getProcessorAnalysisInputs(GrProcessorAnalysisColor* color,
+                                    GrProcessorAnalysisCoverage* coverage) const override {
+        color->setToUnknown();
+        *coverage = GrProcessorAnalysisCoverage::kSingleChannel;
+    }
+
+    void applyPipelineOptimizations(const PipelineOptimizations& optimizations) override {
+        optimizations.getOverrideColorIfSet(&fColor);
+    }
+
+    bool onCombineIfPossible(GrOp*, const GrCaps&) override { return false; }
+
+    void onPrepareDraws(Target* target) const override {
+        using namespace GrDefaultGeoProcFactory;
+
+        // The vertex attrib order is always pos, color, local coords.
+        static const int kColorOffset = sizeof(SkPoint);
+        static const int kLocalOffset = sizeof(SkPoint) + sizeof(GrColor);
+
+        sk_sp<GrGeometryProcessor> gp =
+                GrDefaultGeoProcFactory::Make(Color::kPremulGrColorAttribute_Type,
+                                              Coverage::kSolid_Type,
+                                              fHasLocalRect ? LocalCoords::kHasExplicit_Type
+                                                            : LocalCoords::kUnused_Type,
+                                              SkMatrix::I());
+        if (!gp) {
+            SkDebugf("Couldn't create GrGeometryProcessor for GrAtlasedOp\n");
+            return;
+        }
+
+        size_t vertexStride = gp->getVertexStride();
+
+        SkASSERT(fHasLocalRect
+                    ? vertexStride == sizeof(GrDefaultGeoProcFactory::PositionColorLocalCoordAttr)
+                    : vertexStride == sizeof(GrDefaultGeoProcFactory::PositionColorAttr));
+
+        const GrBuffer* indexBuffer;
+        int firstIndex;
+        uint16_t* indices = target->makeIndexSpace(6, &indexBuffer, &firstIndex);
+        if (!indices) {
+            SkDebugf("Indices could not be allocated for GrAtlasedOp.\n");
+            return;
+        }
+
+        const GrBuffer* vertexBuffer;
+        int firstVertex;
+        void* vertices = target->makeVertexSpace(vertexStride, 4, &vertexBuffer, &firstVertex);
+        if (!vertices) {
+            SkDebugf("Vertices could not be allocated for GrAtlasedOp.\n");
+            return;
+        }
+
+        // Setup indices
+        indices[0] = 0;
+        indices[1] = 1;
+        indices[2] = 2;
+        indices[3] = 0;
+        indices[4] = 2;
+        indices[5] = 3;
+
+        // Setup positions
+        SkPoint* position = (SkPoint*) vertices;
+        position->setRectFan(fRect.fLeft, fRect.fTop, fRect.fRight, fRect.fBottom, vertexStride);
+
+        // Setup vertex colors
+        GrColor* color = (GrColor*)((intptr_t)vertices + kColorOffset);
+        for (int i = 0; i < 4; ++i) {
+            *color = fColor;
+            color = (GrColor*)((intptr_t)color + vertexStride);
+        }
+
+        // Setup local coords
+        if (fHasLocalRect) {
+            SkPoint* coords = (SkPoint*)((intptr_t) vertices + kLocalOffset);
+            for (int i = 0; i < 4; i++) {
+                *coords = fLocalQuad.point(i);
+                coords = (SkPoint*)((intptr_t) coords + vertexStride);
+            }
+        }
+
+        GrMesh mesh;
+        mesh.fPrimitiveType = kTriangles_GrPrimitiveType;
+        mesh.fIndexBuffer.reset(indexBuffer);
+        mesh.fIndexCount = 6;
+        mesh.fBaseIndex = firstIndex;
+        mesh.fVertexBuffer.reset(vertexBuffer);
+        mesh.fVertexCount = 4;
+        mesh.fBaseVertex = firstVertex;
+
+        target->draw(gp.get(), this->pipeline(), mesh);
+    }
+
+    typedef GrLegacyMeshDrawOp INHERITED;
+};
+
+#ifdef SK_DEBUG
+#include "SkImageEncoder.h"
+#include "sk_tool_utils.h"
+
+static void save_bm(const SkBitmap& bm, const char name[]) {
+    bool result = sk_tool_utils::EncodeImageToFile(name, bm, SkEncodedImageFormat::kPNG, 100);
+    SkASSERT(result);
+}
+#endif
+
+/*
+ * Atlased ops just draw themselves as textured rects with the texture pixels being
+ * pulled out of the atlas. Their color is based on their ID.
+ */
+class AtlasedRectOp final : public NonAARectOp {
+public:
+    DEFINE_OP_CLASS_ID
+
+    ~AtlasedRectOp() override {
+        fID = -1;
+    }
+
+    const char* name() const override { return "AtlasedRectOp"; }
+
+    int id() const { return fID; }
+
+    static std::unique_ptr<AtlasedRectOp> Make(const SkRect& r, int id) {
+        return std::unique_ptr<AtlasedRectOp>(new AtlasedRectOp(r, id));
+    }
+
+    void setColor(GrColor color) { fColor = color; }
+    void setLocalRect(const SkRect& localRect) {
+        SkASSERT(fHasLocalRect);    // This should've been created to anticipate this
+        fLocalQuad.set(localRect);
+    }
+
+    AtlasedRectOp* next() const { return fNext; }
+    void setNext(AtlasedRectOp* next) {
+        fNext = next;
+    }
+
+private:
+    // We set the initial color of the NonAARectOp based on the ID.
+    // Note that we force creation of a NonAARectOp that has local coords in anticipation of
+    // pulling from the atlas.
+    AtlasedRectOp(const SkRect& r, int id)
+        : INHERITED(ClassID(), r, kColors[id], SkRect::MakeEmpty())
+        , fID(id)
+        , fNext(nullptr) {
+        SkASSERT(fID < kMaxIDs);
+    }
+
+    static const int kMaxIDs = 9;
+    static const SkColor kColors[kMaxIDs];
+
+    int            fID;
+    // The Atlased ops have an internal singly-linked list of ops that land in the same opList
+    AtlasedRectOp* fNext;
+
+    typedef NonAARectOp INHERITED;
+};
+
+const GrColor AtlasedRectOp::kColors[kMaxIDs] = {
+    GrColorPackRGBA(255, 0, 0, 255),
+    GrColorPackRGBA(0, 255, 0, 255),
+    GrColorPackRGBA(0, 0, 255, 255),
+    GrColorPackRGBA(0, 255, 255, 255),
+    GrColorPackRGBA(255, 0, 255, 255),
+    GrColorPackRGBA(255, 255, 0, 255),
+    GrColorPackRGBA(0, 0, 0, 255),
+    GrColorPackRGBA(128, 128, 128, 255),
+    GrColorPackRGBA(255, 255, 255, 255)
+};
+
+static const int kDrawnTileSize = 16;
+
+/*
+ * Rather than performing any rect packing, this atlaser just lays out constant-sized
+ * tiles in an Nx1 row
+ */
+static const int kAtlasTileSize = 2;
+
+/*
+ * This class aggregates the op information required for atlasing
+ */
+class AtlasObject final : public GrOnFlushCallbackObject {
+public:
+    AtlasObject() : fDone(false) { }
+
+    ~AtlasObject() override {
+        SkASSERT(fDone);
+    }
+
+    void markAsDone() {
+        fDone = true;
+    }
+
+    // Insert the new op in an internal singly-linked list for 'opListID'
+    void addOp(uint32_t opListID, AtlasedRectOp* op) {
+        LinkedListHeader* header = nullptr;
+        for (int i = 0; i < fOps.count(); ++i) {
+            if (opListID == fOps[i].fID) {
+                header = &(fOps[i]);
+            }
+        }
+
+        if (!header) {
+            fOps.push({opListID, nullptr});
+            header = &(fOps[fOps.count()-1]);
+        }
+
+        op->setNext(header->fHead);
+        header->fHead = op;
+    }
+
+    // For the time being we need to pre-allocate the atlas.
+    void setAtlasDest(sk_sp<GrTextureProxy> atlasDest) {
+        fAtlasDest = atlasDest;
+    }
+
+    void saveRTC(sk_sp<GrRenderTargetContext> rtc) {
+        SkASSERT(!fRTC);
+        fRTC = rtc;
+    }
+
+#ifdef SK_DEBUG
+    void saveAtlasToDisk() {
+        SkBitmap readBack;
+        readBack.allocN32Pixels(fRTC->width(), fRTC->height());
+
+        bool result = fRTC->readPixels(readBack.info(),
+                                       readBack.getPixels(), readBack.rowBytes(), 0, 0);
+        SkASSERT(result);
+        save_bm(readBack, "atlas-real.png");
+    }
+#endif
+
+    /*
+     * This callback back creates the atlas and updates the AtlasedRectOps to read from it
+     */
+    void preFlush(GrOnFlushResourceProvider* resourceProvider,
+                  const uint32_t* opListIDs, int numOpListIDs,
+                  SkTArray<sk_sp<GrRenderTargetContext>>* results) override {
+        SkASSERT(!results->count());
+
+        // Until MDB is landed we will most-likely only have one opList.
+        SkTDArray<LinkedListHeader*> lists;
+        for (int i = 0; i < numOpListIDs; ++i) {
+            if (LinkedListHeader* list = this->getList(opListIDs[i])) {
+                lists.push(list);
+            }
+        }
+
+        if (!lists.count()) {
+            return; // nothing to atlas
+        }
+
+        // TODO: right now we have to pre-allocate the atlas bc the TextureSamplers need a
+        // hard GrTexture
+#if 0
+        GrSurfaceDesc desc;
+        desc.fFlags = kRenderTarget_GrSurfaceFlag;
+        desc.fWidth = this->numOps() * kAtlasTileSize;
+        desc.fHeight = kAtlasTileSize;
+        desc.fConfig = kRGBA_8888_GrPixelConfig;
+
+        sk_sp<GrRenderTargetContext> rtc = resourceProvider->makeRenderTargetContext(desc,
+                                                                                     nullptr,
+                                                                                     nullptr);
+#else
+        // At this point all the GrAtlasedOp's should have lined up to read from 'atlasDest' and
+        // there should either be two writes to clear it or no writes.
+        SkASSERT(9 == fAtlasDest->getPendingReadCnt_TestOnly());
+        SkASSERT(2 == fAtlasDest->getPendingWriteCnt_TestOnly() ||
+                 0 == fAtlasDest->getPendingWriteCnt_TestOnly());
+        sk_sp<GrRenderTargetContext> rtc = resourceProvider->makeRenderTargetContext(
+                                                                           fAtlasDest,
+                                                                           nullptr, nullptr);
+#endif
+
+        rtc->clear(nullptr, 0xFFFFFFFF, true); // clear the atlas
+
+        int blocksInAtlas = 0;
+        for (int i = 0; i < lists.count(); ++i) {
+            for (AtlasedRectOp* op = lists[i]->fHead; op; op = op->next()) {
+                SkIRect r = SkIRect::MakeXYWH(blocksInAtlas*kAtlasTileSize, 0,
+                                              kAtlasTileSize, kAtlasTileSize);
+
+                // For now, we avoid the resource buffer issues and just use clears
+#if 1
+                rtc->clear(&r, op->color(), false);
+#else
+                std::unique_ptr<GrDrawOp> drawOp(GrNonAARectOp::Make(SkRect::Make(r),
+                                                 atlasedOp->color()));
+
+                GrPaint paint;
+                rtc->priv().testingOnly_addDrawOp(std::move(paint),
+                                                  GrAAType::kNone,
+                                                  std::move(drawOp));
+#endif
+                blocksInAtlas++;
+
+                // Set the atlased Op's color to white (so we know we're not using it for
+                // the final draw).
+                op->setColor(0xFFFFFFFF);
+
+                // Set the atlased Op's localRect to point to where it landed in the atlas
+                op->setLocalRect(SkRect::Make(r));
+
+                // TODO: we also need to set the op's GrSuperDeferredSimpleTextureEffect to point
+                // to the rtc's proxy!
+            }
+
+            // We've updated all these ops and we certainly don't want to process them again
+            this->clearOpsFor(lists[i]);
+        }
+
+        // Hide a ref to the RTC in AtlasData so we can check on it later
+        this->saveRTC(rtc);
+
+        results->push_back(std::move(rtc));
+    }
+
+private:
+    typedef struct {
+        uint32_t       fID;
+        AtlasedRectOp* fHead;
+    } LinkedListHeader;
+
+    LinkedListHeader* getList(uint32_t opListID) {
+        for (int i = 0; i < fOps.count(); ++i) {
+            if (opListID == fOps[i].fID) {
+                return &(fOps[i]);
+            }
+        }
+        return nullptr;
+    }
+
+    void clearOpsFor(LinkedListHeader* header) {
+        // The AtlasedRectOps have yet to execute (and this class doesn't own them) so just
+        // forget about them in the laziest way possible.
+        header->fHead = nullptr;
+        header->fID = 0;            // invalid opList ID
+    }
+
+    // Each opList containing AtlasedRectOps gets its own internal singly-linked list
+    SkTDArray<LinkedListHeader>  fOps;
+
+    // The RTC used to create the atlas
+    sk_sp<GrRenderTargetContext> fRTC;
+
+    // For the time being we need to pre-allocate the atlas bc the TextureSamplers require
+    // a GrTexture
+    sk_sp<GrTextureProxy>        fAtlasDest;
+
+    // Set to true when the testing harness expects this object to be no longer used
+    bool                         fDone;
+};
+
+// This creates an off-screen rendertarget whose ops which eventually pull from the atlas.
+static sk_sp<GrTextureProxy> make_upstream_image(GrContext* context, AtlasObject* object, int start,
+                                                 sk_sp<GrTextureProxy> fakeAtlas) {
+
+    sk_sp<GrRenderTargetContext> rtc(context->makeDeferredRenderTargetContext(
+                                                                      SkBackingFit::kApprox,
+                                                                      3*kDrawnTileSize,
+                                                                      kDrawnTileSize,
+                                                                      kRGBA_8888_GrPixelConfig,
+                                                                      nullptr));
+
+    rtc->clear(nullptr, GrColorPackRGBA(255, 0, 0, 255), true);
+
+    for (int i = 0; i < 3; ++i) {
+        SkRect r = SkRect::MakeXYWH(i*kDrawnTileSize, 0, kDrawnTileSize, kDrawnTileSize);
+
+        std::unique_ptr<AtlasedRectOp> op(AtlasedRectOp::Make(r, start+i));
+
+        // TODO: here is the blocker for deferring creation of the atlas. The TextureSamplers
+        // created here currently require a hard GrTexture.
+        sk_sp<GrFragmentProcessor> fp = GrSimpleTextureEffect::Make(context->resourceProvider(),
+                                                                    fakeAtlas,
+                                                                    nullptr, SkMatrix::I());
+
+        GrPaint paint;
+        paint.addColorFragmentProcessor(std::move(fp));
+        paint.setPorterDuffXPFactory(SkBlendMode::kSrc);
+
+        AtlasedRectOp* sparePtr = op.get();
+
+        uint32_t opListID = rtc->priv().testingOnly_addLegacyMeshDrawOp(
+                std::move(paint), GrAAType::kNone, std::move(op));
+
+        object->addOp(opListID, sparePtr);
+    }
+
+    return rtc->asTextureProxyRef();
+}
+
+// Enable this if you want to debug the final draws w/o having the atlasCallback create the
+// atlas
+#if 0
+#include "SkGrPriv.h"
+
+sk_sp<GrTextureProxy> pre_create_atlas(GrContext* context) {
+    SkBitmap bm;
+    bm.allocN32Pixels(18, 2, true);
+    bm.erase(SK_ColorRED,     SkIRect::MakeXYWH(0, 0, 2, 2));
+    bm.erase(SK_ColorGREEN,   SkIRect::MakeXYWH(2, 0, 2, 2));
+    bm.erase(SK_ColorBLUE,    SkIRect::MakeXYWH(4, 0, 2, 2));
+    bm.erase(SK_ColorCYAN,    SkIRect::MakeXYWH(6, 0, 2, 2));
+    bm.erase(SK_ColorMAGENTA, SkIRect::MakeXYWH(8, 0, 2, 2));
+    bm.erase(SK_ColorYELLOW,  SkIRect::MakeXYWH(10, 0, 2, 2));
+    bm.erase(SK_ColorBLACK,   SkIRect::MakeXYWH(12, 0, 2, 2));
+    bm.erase(SK_ColorGRAY,    SkIRect::MakeXYWH(14, 0, 2, 2));
+    bm.erase(SK_ColorWHITE,   SkIRect::MakeXYWH(16, 0, 2, 2));
+
+#if 1
+    save_bm(bm, "atlas-fake.png");
+#endif
+
+    GrSurfaceDesc desc = GrImageInfoToSurfaceDesc(bm.info(), *context->caps());
+    desc.fFlags |= kRenderTarget_GrSurfaceFlag;
+
+    sk_sp<GrSurfaceProxy> tmp = GrSurfaceProxy::MakeDeferred(*context->caps(),
+                                                             context->textureProvider(),
+                                                             desc, SkBudgeted::kYes,
+                                                             bm.getPixels(), bm.rowBytes());
+
+    return sk_ref_sp(tmp->asTextureProxy());
+}
+#else
+// TODO: this is unfortunate and must be removed. We want the atlas to be created later.
+sk_sp<GrTextureProxy> pre_create_atlas(GrContext* context) {
+    GrSurfaceDesc desc;
+    desc.fFlags = kRenderTarget_GrSurfaceFlag;
+    desc.fConfig = kSkia8888_GrPixelConfig;
+    desc.fOrigin = kBottomLeft_GrSurfaceOrigin;
+    desc.fWidth = 32;
+    desc.fHeight = 16;
+    sk_sp<GrSurfaceProxy> atlasDest = GrSurfaceProxy::MakeDeferred(
+                                                            context->resourceProvider(),
+                                                            desc, SkBackingFit::kExact,
+                                                            SkBudgeted::kYes,
+                                                            GrResourceProvider::kNoPendingIO_Flag);
+    return sk_ref_sp(atlasDest->asTextureProxy());
+}
+#endif
+
+static void test_color(skiatest::Reporter* reporter, const SkBitmap& bm, int x, SkColor expected) {
+    SkColor readback = bm.getColor(x, kDrawnTileSize/2);
+    REPORTER_ASSERT(reporter, expected == readback);
+    if (expected != readback) {
+        SkDebugf("Color mismatch: %x %x\n", expected, readback);
+    }
+}
+
+/*
+ * For the atlasing test we make a DAG that looks like:
+ *
+ *    RT1 with ops: 0,1,2       RT2 with ops: 3,4,5       RT3 with ops: 6,7,8
+ *                     \         /
+ *                      \       /
+ *                         RT4
+ * We then flush RT4 and expect only ops 0-5 to be atlased together.
+ * Each op is just a solid colored rect so both the atlas and the final image should appear as:
+ *           R G B C M Y
+ * with the atlas having width = 6*kAtlasTileSize and height = kAtlasTileSize.
+ *
+ * Note: until MDB lands, the atlas will actually have width= 9*kAtlasTileSize and look like:
+ *           R G B C M Y K Grey White
+ */
+DEF_GPUTEST_FOR_GL_RENDERING_CONTEXTS(OnFlushCallbackTest, reporter, ctxInfo) {
+    static const int kNumProxies = 3;
+
+    GrContext* context = ctxInfo.grContext();
+
+    if (context->caps()->useDrawInsteadOfClear()) {
+        // TODO: fix the buffer issues so this can run on all devices
+        return;
+    }
+
+    AtlasObject object;
+
+    // For now (until we add a GrSuperDeferredSimpleTextureEffect), we create the final atlas
+    // proxy ahead of time.
+    sk_sp<GrTextureProxy> atlasDest = pre_create_atlas(context);
+
+    object.setAtlasDest(atlasDest);
+
+    context->contextPriv().addOnFlushCallbackObject(&object);
+
+    sk_sp<GrTextureProxy> proxies[kNumProxies];
+    for (int i = 0; i < kNumProxies; ++i) {
+        proxies[i] = make_upstream_image(context, &object, i*3, atlasDest);
+    }
+
+    static const int kFinalWidth = 6*kDrawnTileSize;
+    static const int kFinalHeight = kDrawnTileSize;
+
+    sk_sp<GrRenderTargetContext> rtc(context->makeDeferredRenderTargetContext(
+                                                                      SkBackingFit::kApprox,
+                                                                      kFinalWidth,
+                                                                      kFinalHeight,
+                                                                      kRGBA_8888_GrPixelConfig,
+                                                                      nullptr));
+
+    rtc->clear(nullptr, 0xFFFFFFFF, true);
+
+    // Note that this doesn't include the third texture proxy
+    for (int i = 0; i < kNumProxies-1; ++i) {
+        SkRect r = SkRect::MakeXYWH(i*3*kDrawnTileSize, 0, 3*kDrawnTileSize, kDrawnTileSize);
+
+        SkMatrix t = SkMatrix::MakeTrans(-i*3*kDrawnTileSize, 0);
+
+        GrPaint paint;
+        sk_sp<GrFragmentProcessor> fp(GrSimpleTextureEffect::Make(context->resourceProvider(),
+                                                                  std::move(proxies[i]),
+                                                                  nullptr, t));
+        paint.setPorterDuffXPFactory(SkBlendMode::kSrc);
+        paint.addColorFragmentProcessor(std::move(fp));
+
+        rtc->drawRect(GrNoClip(), std::move(paint), GrAA::kNo, SkMatrix::I(), r);
+    }
+
+    rtc->prepareForExternalIO();
+
+    SkBitmap readBack;
+    readBack.allocN32Pixels(kFinalWidth, kFinalHeight);
+
+    SkDEBUGCODE(bool result =) rtc->readPixels(readBack.info(), readBack.getPixels(),
+                                               readBack.rowBytes(), 0, 0);
+    SkASSERT(result);
+
+    context->contextPriv().testingOnly_flushAndRemoveOnFlushCallbackObject(&object);
+
+    object.markAsDone();
+
+#if 0
+    save_bm(readBack, "atlas-final-image.png");
+    data.saveAtlasToDisk();
+#endif
+
+    int x = kDrawnTileSize/2;
+    test_color(reporter, readBack, x, SK_ColorRED);
+    x += kDrawnTileSize;
+    test_color(reporter, readBack, x, SK_ColorGREEN);
+    x += kDrawnTileSize;
+    test_color(reporter, readBack, x, SK_ColorBLUE);
+    x += kDrawnTileSize;
+    test_color(reporter, readBack, x, SK_ColorCYAN);
+    x += kDrawnTileSize;
+    test_color(reporter, readBack, x, SK_ColorMAGENTA);
+    x += kDrawnTileSize;
+    test_color(reporter, readBack, x, SK_ColorYELLOW);
+}
+
+#endif