Clean up GrBatchAtlas a bit

src/gpu/GrBatchAtlas.cpp

Index: src/gpu/GrBatchAtlas.cpp
diff --git a/src/gpu/GrBatchAtlas.cpp b/src/gpu/GrBatchAtlas.cpp
index ebd0907841ce3bb1f17694b5315f30aace5ad420..8f866e72eaaae436b546e085bee0f8e1c176c265 100644
--- a/src/gpu/GrBatchAtlas.cpp
+++ b/src/gpu/GrBatchAtlas.cpp
@@ -11,42 +11,35 @@
 #include "GrTracing.h"
 #include "GrVertexBuffer.h"
 
-static inline void adjust_for_offset(SkIPoint16* loc, const SkIPoint16& offset) {
-    loc->fX += offset.fX;
-    loc->fY += offset.fY;
-}
-
-static GrBatchAtlas::AtlasID create_id(uint32_t index, uint64_t generation) {
-    SkASSERT(index < (1 << 16));
-    SkASSERT(generation < ((uint64_t)1 << 48));
-    return generation << 16 | index;
-}
-
-// The backing GrTexture for a GrBatchAtlas is broken into a spatial grid of GrBatchPlots.
-// The GrBatchPlots keep track of subimage placement via their GrRectanizer. In turn, a GrBatchPlot
-// manages the lifetime of its data using two tokens, a last ref toke and a last upload token.
-// Once a GrBatchPlot is "full" (i.e. there is no room for the new subimage according to the
-// GrRectanizer), it can no longer be used unless the last ref on the GrPlot has already been
+// The backing GrTexture for a GrBatchAtlas is broken into a spatial grid of BatchPlots.
+// The BatchPlots keep track of subimage placement via their GrRectanizer. A BatchPlot
+// manages the lifetime of its data using two tokens, a last use token and a last upload token.
+// Once a BatchPlot is "full" (i.e. there is no room for the new subimage according to the
+// GrRectanizer), it can no longer be used unless the last use of the GrPlot has already been
 // flushed through to the gpu.
 
 class BatchPlot : public SkRefCnt {
-public:
     SK_DECLARE_INTERNAL_LLIST_INTERFACE(BatchPlot);
 
-    // index() refers to the index of the plot in the owning GrAtlas's plot array.  genID() is a
-    // monotonically incrementing number which is bumped every time the cpu backing store is
-    // wiped, or when the plot itself is evicted from the atlas(ie, there is continuity in genID()
-    // across atlas spills)
+public:
+    // index() is a unique id for the plot relative to the owning GrAtlas.  genID() is a
+    // monotonically incremented number which is bumped every time this plot is 
+    // evicted from the cache (i.e., there is continuity in genID() across atlas spills).
     uint32_t index() const { return fIndex; }
     uint64_t genID() const { return fGenID; }
-    GrBatchAtlas::AtlasID id() {
+    GrBatchAtlas::AtlasID id() const {
         SkASSERT(GrBatchAtlas::kInvalidAtlasID != fID);
         return fID;
     }
+    SkDEBUGCODE(size_t bpp() const { return fBytesPerPixel; })
 
-    GrTexture* texture() const { return fTexture; }
+    bool addSubImage(int width, int height, const void* image, SkIPoint16* loc)  {
+        SkASSERT(width <= fWidth && height <= fHeight);
+
+        if (!fRects) {
+            fRects = GrRectanizer::Factory(fWidth, fHeight);
+        }
 
-    bool addSubImage(int width, int height, const void* image, SkIPoint16* loc, size_t rowBytes)  {
         if (!fRects->addRect(width, height, loc)) {
             return false;
         }
@@ -55,6 +48,7 @@ public:
             fData = reinterpret_cast<unsigned char*>(sk_calloc_throw(fBytesPerPixel * fWidth *
                                                                      fHeight));
         }
+        size_t rowBytes = width * fBytesPerPixel;
         const unsigned char* imagePtr = (const unsigned char*)image;
         // point ourselves at the right starting spot
         unsigned char* dataPtr = fData;
@@ -68,17 +62,19 @@ public:
         }
 
         fDirtyRect.join(loc->fX, loc->fY, loc->fX + width, loc->fY + height);
-        adjust_for_offset(loc, fOffset);
+
+        loc->fX += fOffset.fX;
+        loc->fY += fOffset.fY;
         SkDEBUGCODE(fDirty = true;)
 
         return true;
     }
 
-    // to manage the lifetime of a plot, we use two tokens.  We use last upload token to know when
-    // we can 'piggy back' uploads, ie if the last upload hasn't been flushed to gpu, we don't need
-    // to issue a new upload even if we update the cpu backing store.  We use lastref to determine
-    // when we can evict a plot from the cache, ie if the last ref has already flushed through
-    // the gpu then we can reuse the plot
+    // To manage the lifetime of a plot, we use two tokens.  We use the last upload token to know
+    // when we can 'piggy back' uploads, ie if the last upload hasn't been flushed to gpu, we don't
+    // need to issue a new upload even if we update the cpu backing store.  We use lastUse to
+    // determine when we can evict a plot from the cache, ie if the last use has already flushed
+    // through the gpu then we can reuse the plot.
     GrBatchToken lastUploadToken() const { return fLastUpload; }
     GrBatchToken lastUseToken() const { return fLastUse; }
     void setLastUploadToken(GrBatchToken batchToken) {
@@ -90,27 +86,29 @@ public:
         fLastUse = batchToken;
     }
 
-    void uploadToTexture(GrBatchUploader::TextureUploader* uploader)  {
+    void uploadToTexture(GrBatchUploader::TextureUploader* uploader, GrTexture* texture)  {
         // We should only be issuing uploads if we are in fact dirty
-        SkASSERT(fDirty && fData && fTexture);
+        SkASSERT(fDirty && fData && texture);
         TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("skia.gpu"), "GrBatchPlot::uploadToTexture");
-        size_t rowBytes = fBytesPerPixel * fRects->width();
+        size_t rowBytes = fBytesPerPixel * fWidth;
         const unsigned char* dataPtr = fData;
         dataPtr += rowBytes * fDirtyRect.fTop;
         dataPtr += fBytesPerPixel * fDirtyRect.fLeft;
-        uploader->writeTexturePixels(fTexture,
+        uploader->writeTexturePixels(texture,
                                      fOffset.fX + fDirtyRect.fLeft, fOffset.fY + fDirtyRect.fTop,
                                      fDirtyRect.width(), fDirtyRect.height(),
-                                     fTexture->config(), dataPtr, rowBytes);
+                                     fConfig, dataPtr, rowBytes);
         fDirtyRect.setEmpty();
         SkDEBUGCODE(fDirty = false;)
     }
 
     void resetRects() {
-        SkASSERT(fRects);
-        fRects->reset();
+        if (fRects) {
+            fRects->reset();
+        }
+
         fGenID++;
-        fID = create_id(fIndex, fGenID);
+        fID = CreateId(fIndex, fGenID);
 
         // zero out the plot
         if (fData) {
@@ -121,75 +119,64 @@ public:
         SkDEBUGCODE(fDirty = false;)
     }
 
-    uint32_t x() const { return fX; }
-    uint32_t y() const { return fY; }
-
 private:
-    BatchPlot()
+    BatchPlot(int index, uint64_t genID, int offX, int offY, int width, int height, 
+              GrPixelConfig config)
         : fLastUpload(0)
         , fLastUse(0)
-        , fIndex(-1)
-        , fGenID(-1)
-        , fID(0)
+        , fIndex(index)
+        , fGenID(genID)
+        , fID(CreateId(fIndex, fGenID))
         , fData(nullptr)
-        , fWidth(0)
-        , fHeight(0)
-        , fX(0)
-        , fY(0)
-        , fTexture(nullptr)
+        , fWidth(width)
+        , fHeight(height)
+        , fX(offX)
+        , fY(offY)
         , fRects(nullptr)
-        , fAtlas(nullptr)
-        , fBytesPerPixel(1)
+        , fOffset(SkIPoint16::Make(fX * fWidth, fY * fHeight))
+        , fConfig(config)
+        , fBytesPerPixel(GrBytesPerPixel(config))
     #ifdef SK_DEBUG
         , fDirty(false)
     #endif
     {
-        fOffset.set(0, 0);
+        fDirtyRect.setEmpty();
     }
 
-    ~BatchPlot() {
+    ~BatchPlot() override {
         sk_free(fData);
-        fData = nullptr;
         delete fRects;
     }
 
-    void init(GrBatchAtlas* atlas, GrTexture* texture, int index, uint64_t generation,
-              int offX, int offY, int width, int height, size_t bpp) {
-        fIndex = index;
-        fGenID = generation;
-        fID = create_id(index, generation);
-        fWidth = width;
-        fHeight = height;
-        fX = offX;
-        fY = offY;
-        fRects = GrRectanizer::Factory(width, height);
-        fAtlas = atlas;
-        fOffset.set(offX * width, offY * height);
-        fBytesPerPixel = bpp;
-        fData = nullptr;
-        fDirtyRect.setEmpty();
-        SkDEBUGCODE(fDirty = false;)
-        fTexture = texture;
+    // Create a clone of this plot. The cloned plot will take the place of the
+    // current plot in the atlas.
+    BatchPlot* clone() const {
+        return new BatchPlot(fIndex, fGenID+1, fX, fY, fWidth, fHeight, fConfig);
+    }
+
+    static GrBatchAtlas::AtlasID CreateId(uint32_t index, uint64_t generation) {
+        SkASSERT(index < (1 << 16));
+        SkASSERT(generation < ((uint64_t)1 << 48));
+        return generation << 16 | index;
     }
 
-    GrBatchToken fLastUpload;
-    GrBatchToken fLastUse;
+    GrBatchToken          fLastUpload;
+    GrBatchToken          fLastUse;
 
-    uint32_t fIndex;
-    uint64_t fGenID;
+    const uint32_t        fIndex;
+    uint64_t              fGenID;
     GrBatchAtlas::AtlasID fID;
-    unsigned char* fData;
-    uint32_t fWidth;
-    uint32_t fHeight;
-    uint32_t fX;
-    uint32_t fY;
-    GrTexture* fTexture;
-    GrRectanizer* fRects;
-    GrBatchAtlas* fAtlas;
-    SkIPoint16 fOffset;        // the offset of the plot in the backing texture
-    size_t fBytesPerPixel;
-    SkIRect fDirtyRect;
-    SkDEBUGCODE(bool fDirty;)
+    unsigned char*        fData;
+    const int             fWidth;
+    const int             fHeight;
+    const int             fX;
+    const int             fY;
+    GrRectanizer*         fRects;
+    const SkIPoint16      fOffset;        // the offset of the plot in the backing texture
+    const GrPixelConfig   fConfig;
+    const size_t          fBytesPerPixel;
+    SkIRect               fDirtyRect;
+    SkDEBUGCODE(bool      fDirty;)
 
     friend class GrBatchAtlas;
 
@@ -200,18 +187,20 @@ private:
 
 class GrPlotUploader : public GrBatchUploader {
 public:
-    GrPlotUploader(BatchPlot* plot)
+    GrPlotUploader(BatchPlot* plot, GrTexture* texture)
         : INHERITED(plot->lastUploadToken())
-        , fPlot(SkRef(plot)) {
+        , fPlot(SkRef(plot))
+        , fTexture(texture) {
         SkASSERT(plot);
     }
 
     void upload(TextureUploader* uploader) override {
-        fPlot->uploadToTexture(uploader);
+        fPlot->uploadToTexture(uploader, fTexture);
     }
 
 private:
     SkAutoTUnref<BatchPlot> fPlot;
+    GrTexture*              fTexture;
 
     typedef GrBatchUploader INHERITED;
 };
@@ -220,28 +209,28 @@ private:
 
 GrBatchAtlas::GrBatchAtlas(GrTexture* texture, int numPlotsX, int numPlotsY)
     : fTexture(texture)
-    , fNumPlotsX(numPlotsX)
-    , fNumPlotsY(numPlotsY)
-    , fPlotWidth(texture->width() / numPlotsX)
-    , fPlotHeight(texture->height() / numPlotsY)
     , fAtlasGeneration(kInvalidAtlasGeneration + 1) {
-    SkASSERT(fNumPlotsX * fNumPlotsY <= BulkUseTokenUpdater::kMaxPlots);
-    SkASSERT(fPlotWidth * fNumPlotsX == static_cast<uint32_t>(texture->width()));
-    SkASSERT(fPlotHeight * fNumPlotsY == static_cast<uint32_t>(texture->height()));
+
+    int plotWidth = texture->width() / numPlotsX;
+    int plotHeight = texture->height() / numPlotsY;
+    SkASSERT(numPlotsX * numPlotsY <= BulkUseTokenUpdater::kMaxPlots);
+    SkASSERT(plotWidth * numPlotsX == texture->width());
+    SkASSERT(plotHeight * numPlotsY == texture->height());
+
+    SkDEBUGCODE(fNumPlots = numPlotsX * numPlotsY;)
 
     // We currently do not support compressed atlases...
     SkASSERT(!GrPixelConfigIsCompressed(texture->desc().fConfig));
 
     // set up allocated plots
-    fBPP = GrBytesPerPixel(texture->desc().fConfig);
-    fPlotArray = new SkAutoTUnref<BatchPlot>[(fNumPlotsX * fNumPlotsY)];
+    fPlotArray = new SkAutoTUnref<BatchPlot>[numPlotsX * numPlotsY];
 
     SkAutoTUnref<BatchPlot>* currPlot = fPlotArray;
-    for (int y = fNumPlotsY - 1, r = 0; y >= 0; --y, ++r) {
-        for (int x = fNumPlotsX - 1, c = 0; x >= 0; --x, ++c) {
-            uint32_t id = r * fNumPlotsX + c;
-            currPlot->reset(new BatchPlot);
-            (*currPlot)->init(this, texture, id, 1, x, y, fPlotWidth, fPlotHeight, fBPP);
+    for (int y = numPlotsY - 1, r = 0; y >= 0; --y, ++r) {
+        for (int x = numPlotsX - 1, c = 0; x >= 0; --x, ++c) {
+            uint32_t index = r * numPlotsX + c;
+            currPlot->reset(new BatchPlot(index, 1, x, y, plotWidth, plotHeight,
+                                          texture->desc().fConfig));
 
             // build LRU list
             fPlotList.addToHead(currPlot->get());
@@ -278,7 +267,7 @@ inline void GrBatchAtlas::updatePlot(GrDrawBatch::Target* target, AtlasID* id, B
     // This new update will piggy back on that previously scheduled update.
     if (target->hasTokenBeenFlushed(plot->lastUploadToken())) {
         plot->setLastUploadToken(target->asapToken());
-        SkAutoTUnref<GrPlotUploader> uploader(new GrPlotUploader(plot));
+        SkAutoTUnref<GrPlotUploader> uploader(new GrPlotUploader(plot, fTexture));
         target->upload(uploader);
     }
     *id = plot->id();
@@ -287,16 +276,15 @@ inline void GrBatchAtlas::updatePlot(GrDrawBatch::Target* target, AtlasID* id, B
 bool GrBatchAtlas::addToAtlas(AtlasID* id, GrDrawBatch::Target* batchTarget,
                               int width, int height, const void* image, SkIPoint16* loc) {
     // We should already have a texture, TODO clean this up
-    SkASSERT(fTexture &&
-             static_cast<uint32_t>(width) <= fPlotWidth &&
-             static_cast<uint32_t>(height) <= fPlotHeight);
+    SkASSERT(fTexture);
 
     // now look through all allocated plots for one we can share, in Most Recently Refed order
     GrBatchPlotList::Iter plotIter;
     plotIter.init(fPlotList, GrBatchPlotList::Iter::kHead_IterStart);
     BatchPlot* plot;
     while ((plot = plotIter.get())) {
-        if (plot->addSubImage(width, height, image, loc, fBPP * width)) {
+        SkASSERT(GrBytesPerPixel(fTexture->desc().fConfig) == plot->bpp());
+        if (plot->addSubImage(width, height, image, loc)) {
             this->updatePlot(batchTarget, id, plot);
             return true;
         }
@@ -305,64 +293,63 @@ bool GrBatchAtlas::addToAtlas(AtlasID* id, GrDrawBatch::Target* batchTarget,
 
     // If the above fails, then see if the least recently refed plot has already been flushed to the
     // gpu
-    plotIter.init(fPlotList, GrBatchPlotList::Iter::kTail_IterStart);
-    plot = plotIter.get();
+    plot = fPlotList.tail();
     SkASSERT(plot);
     if (batchTarget->hasTokenBeenFlushed(plot->lastUseToken())) {
         this->processEviction(plot->id());
         plot->resetRects();
-        SkDEBUGCODE(bool verify = )plot->addSubImage(width, height, image, loc, fBPP * width);
+        SkASSERT(GrBytesPerPixel(fTexture->desc().fConfig) == plot->bpp());
+        SkDEBUGCODE(bool verify = )plot->addSubImage(width, height, image, loc);
         SkASSERT(verify);
         this->updatePlot(batchTarget, id, plot);
         fAtlasGeneration++;
         return true;
     }
 
-    // The least recently refed plot hasn't been flushed to the gpu yet, however, if we have flushed
-    // it to the batch target than we can reuse it.  Our last ref token is guaranteed to be less
+    // The least recently used plot hasn't been flushed to the gpu yet, however, if we have flushed
+    // it to the batch target than we can reuse it.  Our last use token is guaranteed to be less
     // than or equal to the current token.  If its 'less than' the current token, than we can spin
-    // off the plot(ie let the batch target manage it) and create a new plot in its place in our
+    // off the plot (ie let the batch target manage it) and create a new plot in its place in our
     // array.  If it is equal to the currentToken, then the caller has to flush draws to the batch
     // target so we can spin off the plot
     if (plot->lastUseToken() == batchTarget->currentToken()) {
         return false;
     }
 
-    // We take an extra ref here so our plot isn't deleted when we reset its index in the array.
-    plot->ref();
-    int index = plot->index();
-    int x = plot->x();
-    int y = plot->y();
-    uint64_t generation = plot->genID();
+    SkASSERT(plot->lastUseToken() < batchTarget->currentToken());
+    SkASSERT(!batchTarget->hasTokenBeenFlushed(batchTarget->currentToken()));
+
+    SkASSERT(!plot->unique());  // The GrPlotUpdater should have a ref too
 
     this->processEviction(plot->id());
     fPlotList.remove(plot);
     SkAutoTUnref<BatchPlot>& newPlot = fPlotArray[plot->index()];
-    newPlot.reset(new BatchPlot);
-    newPlot->init(this, fTexture, index, ++generation, x, y, fPlotWidth, fPlotHeight, fBPP);
+    newPlot.reset(plot->clone());
 
     fPlotList.addToHead(newPlot.get());
-    SkDEBUGCODE(bool verify = )newPlot->addSubImage(width, height, image, loc, fBPP * width);
+    SkASSERT(GrBytesPerPixel(fTexture->desc().fConfig) == newPlot->bpp());
+    SkDEBUGCODE(bool verify = )newPlot->addSubImage(width, height, image, loc);
     SkASSERT(verify);
+
     newPlot->setLastUploadToken(batchTarget->currentToken());
-    SkAutoTUnref<GrPlotUploader> uploader(new GrPlotUploader(newPlot));
+    SkAutoTUnref<GrPlotUploader> uploader(new GrPlotUploader(newPlot, fTexture));
     batchTarget->upload(uploader);
     *id = newPlot->id();
-    plot->unref();
+
     fAtlasGeneration++;
     return true;
 }
 
 bool GrBatchAtlas::hasID(AtlasID id) {
     uint32_t index = GetIndexFromID(id);
-    SkASSERT(index < fNumPlotsX * fNumPlotsY);
+    SkASSERT(index < fNumPlots);
     return fPlotArray[index]->genID() == GetGenerationFromID(id);
 }
 
 void GrBatchAtlas::setLastUseToken(AtlasID id, GrBatchToken batchToken) {
     SkASSERT(this->hasID(id));
     uint32_t index = GetIndexFromID(id);
-    SkASSERT(index < fNumPlotsX * fNumPlotsY);
+    SkASSERT(index < fNumPlots);
     this->makeMRU(fPlotArray[index]);
     fPlotArray[index]->setLastUseToken(batchToken);
 }