Expose layer hoisting API in GrContext

src/core/SkMultiPictureDraw.cpp

Index: src/core/SkMultiPictureDraw.cpp
diff --git a/src/core/SkMultiPictureDraw.cpp b/src/core/SkMultiPictureDraw.cpp
index eb1e55e5508a749d3908111cc2748c0929137ba8..19b26ca60775e1b03d89cfd34952a936254525d2 100644
--- a/src/core/SkMultiPictureDraw.cpp
+++ b/src/core/SkMultiPictureDraw.cpp
@@ -5,6 +5,11 @@
  * found in the LICENSE file.
  */
 
+#if SK_SUPPORT_GPU
+#include "GrLayerHoister.h"
+#include "GrRecordReplaceDraw.h"
+#endif
+
 #include "SkCanvas.h"
 #include "SkMultiPictureDraw.h"
 #include "SkPicture.h"
@@ -50,12 +55,66 @@ void SkMultiPictureDraw::add(SkCanvas* canvas,
     }
 }
 
+#undef SK_IGNORE_GPU_LAYER_HOISTING
+#define SK_IGNORE_GPU_LAYER_HOISTING 1
+
 void SkMultiPictureDraw::draw() {
+
+#ifndef SK_IGNORE_GPU_LAYER_HOISTING
+    GrContext* context = NULL;
+
+    SkTDArray<GrHoistedLayer> atlased, nonAtlased, recycled;
+
     for (int i = 0; i < fDrawData.count(); ++i) {
-        fDrawData[i].canvas->drawPicture(fDrawData[i].picture, 
-                                         &fDrawData[i].matrix, 
-                                         fDrawData[i].paint);
+        if (fDrawData[i].canvas->getGrContext() &&
+            !fDrawData[i].paint && fDrawData[i].matrix.isIdentity()) {
+            SkASSERT(NULL == context || context == fDrawData[i].canvas->getGrContext());
+            context = fDrawData[i].canvas->getGrContext();
+
+            // TODO: this path always tries to optimize pictures. Should we
+            // switch to this API approach (vs. SkCanvas::EXPERIMENTAL_optimize)?
+            fDrawData[i].canvas->EXPERIMENTAL_optimize(fDrawData[i].picture);
+
+            SkRect clipBounds;
+            if (!fDrawData[i].canvas->getClipBounds(&clipBounds)) {
+                continue;
+            }
+
+            GrLayerHoister::FindLayersToHoist(context, fDrawData[i].picture,
+                                              clipBounds, &atlased, &nonAtlased, &recycled);
+        }
+    }
+
+    GrReplacements replacements;
+
+    if (NULL != context) {
+        GrLayerHoister::DrawLayers(atlased, nonAtlased, recycled, &replacements);
+    }
+#endif
+
+    for (int i = 0; i < fDrawData.count(); ++i) {
+#ifndef SK_IGNORE_GPU_LAYER_HOISTING
+        if (fDrawData[i].canvas->getGrContext() && 
+            !fDrawData[i].paint && fDrawData[i].matrix.isIdentity()) {
+            // Render the entire picture using new layers
+            const SkMatrix initialMatrix = fDrawData[i].canvas->getTotalMatrix();
+
+            GrRecordReplaceDraw(fDrawData[i].picture, fDrawData[i].canvas, 
+                                &replacements, initialMatrix, NULL);
+        } else 
+#endif
+        {
+            fDrawData[i].canvas->drawPicture(fDrawData[i].picture,
+                                             &fDrawData[i].matrix,
+                                             fDrawData[i].paint);
+        }
+    }
+
+#ifndef SK_IGNORE_GPU_LAYER_HOISTING
+    if (NULL != context) {
+        GrLayerHoister::UnlockLayers(context, atlased, nonAtlased, recycled);
     }
+#endif
 
     this->reset();
 }