Alter layer hoisting to only hoist layers for one canvas at a time

src/gpu/GrLayerCache.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrAtlas.h"
 #include "GrGpu.h"
 #include "GrLayerCache.h"
@@ skipping 143 matching lines @@
                                                const SkPaint* paint) {
     SkASSERT(pictureID != SK_InvalidGenID && start >= 0 && stop > 0);
     GrCachedLayer* layer = fLayerHash.find(GrCachedLayer::Key(pictureID, start, bounds, ctm));
     if (NULL == layer) {
         layer = this->createLayer(pictureID, start, stop, bounds, ctm, paint);
     }
 
     return layer;
 }
 
-bool GrLayerCache::lock(GrCachedLayer* layer, const GrTextureDesc& desc, bool dontAtlas) {
+bool GrLayerCache::tryToAtlas(GrCachedLayer* layer, 
+                              const GrTextureDesc& desc, 
+                              bool* needsRendering) {
     SkDEBUGCODE(GrAutoValidateLayer avl(fAtlas->getTexture(), layer);)
 
+    SkASSERT(PlausiblyAtlasable(desc.fWidth, desc.fHeight));
+
     if (layer->locked()) {
         // This layer is already locked
-#ifdef SK_DEBUG
-        if (layer->isAtlased()) {
-            // It claims to be atlased
-            SkASSERT(!dontAtlas);
-            SkASSERT(layer->rect().width() == desc.fWidth);
-            SkASSERT(layer->rect().height() == desc.fHeight);
-        }
-#endif
-        return false;
+        SkASSERT(layer->isAtlased());
+        SkASSERT(layer->rect().width() == desc.fWidth);
+        SkASSERT(layer->rect().height() == desc.fHeight);
+        *needsRendering = false;
+        return true;
     }
 
     if (layer->isAtlased()) {
         // Hooray it is still in the atlas - make sure it stays there
-        SkASSERT(!dontAtlas);
         layer->setLocked(true);
         this->incPlotLock(layer->plot()->id());
-        return false;
-    } else if (!dontAtlas && PlausiblyAtlasable(desc.fWidth, desc.fHeight)) {
+        *needsRendering = false;
+        return true;
+    } else {
         // Not in the atlas - will it fit?
         GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
         if (NULL == pictInfo) {
             pictInfo = SkNEW_ARGS(GrPictureInfo, (layer->pictureID()));
             fPictureHash.add(pictInfo);
         }
 
         SkIPoint16 loc;
         for (int i = 0; i < 2; ++i) { // extra pass in case we fail to add but are able to purge
             GrPlot* plot = fAtlas->addToAtlas(&pictInfo->fPlotUsage,
                                               desc.fWidth, desc.fHeight,
                                               NULL, &loc);
             // addToAtlas can allocate the backing texture
             SkDEBUGCODE(avl.setBackingTexture(fAtlas->getTexture()));
             if (plot) {
                 // The layer was successfully added to the atlas
                 GrIRect16 bounds = GrIRect16::MakeXYWH(loc.fX, loc.fY,
                                                        SkToS16(desc.fWidth),
                                                        SkToS16(desc.fHeight));
                 layer->setTexture(fAtlas->getTexture(), bounds);
                 layer->setPlot(plot);
                 layer->setLocked(true);
                 this->incPlotLock(layer->plot()->id());
+                *needsRendering = true;
                 return true;
             }
 
             // The layer was rejected by the atlas (even though we know it is 
             // plausibly atlas-able). See if a plot can be purged and try again.
             if (!this->purgePlot()) {
                 break;  // We weren't able to purge any plots
             }
         }
     }
 
-    // The texture wouldn't fit in the cache - give it it's own texture.
-    // This path always uses a new scratch texture and (thus) doesn't cache anything.
-    // This can yield a lot of re-rendering
+    return false;
+}
+
+bool GrLayerCache::lock(GrCachedLayer* layer, const GrTextureDesc& desc, bool* needsRendering) {
+    if (layer->locked()) {
+        // This layer is already locked
+        *needsRendering = false;
+        return true;
+    }
+
     SkAutoTUnref<GrTexture> tex(
         fContext->refScratchTexture(desc, GrContext::kApprox_ScratchTexMatch));
 
+    if (!tex) {
+        return false;
+    }
+
     layer->setTexture(tex, GrIRect16::MakeWH(SkToS16(desc.fWidth), SkToS16(desc.fHeight)));
     layer->setLocked(true);
+    *needsRendering = true;
     return true;
 }
 
 void GrLayerCache::unlock(GrCachedLayer* layer) {
     SkDEBUGCODE(GrAutoValidateLayer avl(fAtlas->getTexture(), layer);)
 
     if (NULL == layer || !layer->locked()) {
         // invalid or not locked
         return;
     }
@@ skipping 29 matching lines @@
     int plotLocks[kNumPlotsX * kNumPlotsY];
     memset(plotLocks, 0, sizeof(plotLocks));
 
     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::ConstIter iter(&fLayerHash);
     for (; !iter.done(); ++iter) {
         const GrCachedLayer* layer = &(*iter);
 
         layer->validate(fAtlas->getTexture());
 
         const GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
-        if (pictInfo) {
-            // In aggressive cleanup mode a picture info should only exist if
-            // it has some atlased layers
-#if !DISABLE_CACHING
-            SkASSERT(!pictInfo->fPlotUsage.isEmpty());
-#endif
-        } else {
+        if (!pictInfo) {
             // If there is no picture info for this picture then all of its
             // layers should be non-atlased.
             SkASSERT(!layer->isAtlased());
         }
 
         if (layer->plot()) {
             SkASSERT(pictInfo);
             SkASSERT(pictInfo->fPictureID == layer->pictureID());
 
             SkASSERT(pictInfo->fPlotUsage.contains(layer->plot()));
@@ skipping 162 matching lines @@
             continue;
         }
 
         SkString fileName(dirName);
         fileName.appendf("\\%d-%d.png", layer->fKey.pictureID(), layer->fKey.start());
 
         layer->texture()->surfacePriv().savePixels(fileName.c_str());
     }
 }
 #endif