cc: Adding support for RGBA_4444 tile textures

cc/resources/raster_worker_pool.cc

Index: cc/resources/raster_worker_pool.cc
diff --git a/cc/resources/raster_worker_pool.cc b/cc/resources/raster_worker_pool.cc
index 15b8aa41133312b094cec77d073ab1c5c954e41f..92ae4aec991800f0422bd864182519159578d888 100644
--- a/cc/resources/raster_worker_pool.cc
+++ b/cc/resources/raster_worker_pool.cc
@@ -11,13 +11,28 @@
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/traced_value.h"
 #include "cc/resources/picture_pile_impl.h"
+#include "cc/resources/resource_provider.h"
 #include "skia/ext/lazy_pixel_ref.h"
 #include "skia/ext/paint_simplifier.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 
 namespace cc {
 
 namespace {
 
+// Subclass of Allocator that takes a suitably allocated pointer and uses
+// it as the pixel memory for the bitmap.
+class IdentityAllocator : public SkBitmap::Allocator {
+ public:
+  explicit IdentityAllocator(void* buffer) : buffer_(buffer) {}
+  virtual bool allocPixelRef(SkBitmap* dst, SkColorTable*) OVERRIDE {
+    dst->setPixels(buffer_);
+    return true;
+  }
+ private:
+  void* buffer_;
+};
+
 // Flag to indicate whether we should try and detect that
 // a tile is of solid color.
 const bool kUseColorEstimator = true;
@@ -34,6 +49,32 @@ class DisableLCDTextFilter : public SkDrawFilter {
   }
 };
 
+SkBitmap::Config SkBitmapConfigFromFormat(ResourceProvider::Format format) {
+  switch (format) {
+    case ResourceProvider::RGBA_4444:
+      return SkBitmap::kARGB_4444_Config;
+    case ResourceProvider::RGBA_8888:
+    case ResourceProvider::BGRA_8888:
+      return SkBitmap::kARGB_8888_Config;
+    case ResourceProvider::LUMINANCE_8:
+      NOTREACHED();
+      break;
+  }
+  NOTREACHED();
+  return SkBitmap::kARGB_8888_Config;
+}
+
+void ChangeBitmapConfigIfPossible(const SkBitmap& bitmap,
+                                  void* buffer,
+                                  ResourceProvider::Format format) {
+  TRACE_EVENT0("cc", "ChangeBitmapConfig");
+  if (bitmap.getConfig() != SkBitmapConfigFromFormat(format)) {
+    SkBitmap bitmap_dest;
+    IdentityAllocator allocator(buffer);
+    bitmap.copyTo(&bitmap_dest, SkBitmapConfigFromFormat(format), &allocator);
+  }
+}
+
 class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
  public:
   RasterWorkerPoolTaskImpl(const Resource* resource,
@@ -89,7 +130,10 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
     analysis_.is_solid_color &= kUseColorEstimator;
   }
 
-  bool RunRasterOnThread(SkBaseDevice* device, unsigned thread_index) {
+  bool RunRasterOnThread(unsigned thread_index,
+                         void* buffer,
+                         gfx::Size size,
+                         int stride) {
     TRACE_EVENT2(
         benchmark_instrumentation::kCategory,
         benchmark_instrumentation::kRunRasterOnThread,
@@ -102,7 +146,7 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
         devtools_instrumentation::kRasterTask, layer_id_);
 
     DCHECK(picture_pile_.get());
-    DCHECK(device);
+    DCHECK(buffer);
 
     if (analysis_.is_solid_color)
       return false;
@@ -110,8 +154,31 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
     PicturePileImpl* picture_clone =
         picture_pile_->GetCloneForDrawingOnThread(thread_index);
 
-    SkCanvas canvas(device);
+    SkBitmap bitmap;
+    switch (resource()->format()) {
+      case ResourceProvider::RGBA_4444:
+        // Use the default stride if we will eventually convert this
+        // bitmap to 4444.
+        bitmap.setConfig(SkBitmap::kARGB_8888_Config,
+                         size.width(),
+                         size.height());
+        bitmap.allocPixels();
+        break;
+      case ResourceProvider::RGBA_8888:
+      case ResourceProvider::BGRA_8888:
+        bitmap.setConfig(SkBitmap::kARGB_8888_Config,
+                         size.width(),
+                         size.height(),
+                         stride);
+        bitmap.setPixels(buffer);
+        break;
+      case ResourceProvider::LUMINANCE_8:
+        NOTREACHED();
+        break;
+    }
 
+    SkBitmapDevice device(bitmap);
+    SkCanvas canvas(&device);
     skia::RefPtr<SkDrawFilter> draw_filter;
     switch (raster_mode_) {
       case LOW_QUALITY_RASTER_MODE:
@@ -149,14 +216,20 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
       picture_clone->RasterToBitmap(
           &canvas, content_rect_, contents_scale_, NULL);
     }
+
+    ChangeBitmapConfigIfPossible(bitmap, buffer, resource()->format());
+
     return true;
   }
 
   // Overridden from internal::RasterWorkerPoolTask:
-  virtual bool RunOnWorkerThread(SkBaseDevice* device, unsigned thread_index)
+  virtual bool RunOnWorkerThread(unsigned thread_index,
+                                 void* buffer,
+                                 gfx::Size size,
+                                 int stride)
       OVERRIDE {
     RunAnalysisOnThread(thread_index);
-    return RunRasterOnThread(device, thread_index);
+    return RunRasterOnThread(thread_index, buffer, size, stride);
   }
   virtual void CompleteOnOriginThread() OVERRIDE {
     reply_.Run(analysis_, !HasFinishedRunning() || WasCanceled());