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..f5c795520db7d67c4ac1a65008d5c02c3ab406a6 100644
--- a/cc/resources/raster_worker_pool.cc
+++ b/cc/resources/raster_worker_pool.cc
@@ -13,11 +13,25 @@
 #include "cc/resources/picture_pile_impl.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;
@@ -48,7 +62,8 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
                            int source_frame_number,
                            RenderingStatsInstrumentation* rendering_stats,
                            const RasterWorkerPool::RasterTask::Reply& reply,
-                           TaskVector* dependencies)
+                           TaskVector* dependencies,
+                           bool use_16bit_tiles)
       : internal::RasterWorkerPoolTask(resource, dependencies),
         picture_pile_(picture_pile),
         content_rect_(content_rect),
@@ -60,7 +75,8 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
         tile_id_(tile_id),
         source_frame_number_(source_frame_number),
         rendering_stats_(rendering_stats),
-        reply_(reply) {}
+        reply_(reply),
+        use_16bit_tiles_(use_16bit_tiles) {}
 
   void RunAnalysisOnThread(unsigned thread_index) {
     TRACE_EVENT1("cc",
@@ -89,7 +105,9 @@ 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) {
     TRACE_EVENT2(
         benchmark_instrumentation::kCategory,
         benchmark_instrumentation::kRunRasterOnThread,
@@ -102,7 +120,7 @@ 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 +128,14 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
     PicturePileImpl* picture_clone =
         picture_pile_->GetCloneForDrawingOnThread(thread_index);
 
-    SkCanvas canvas(device);
+    SkBitmap bitmap_32;

[Sami, 2013/09/05 14:13:26]

If we gave this function an SkBitmapDevice instead of SkBaseDevice we wouldn't
need to change much of the existing bitmap allocation logic. To convert to 16
bit you could then do this:

SkBitmap bitmap_32;
bitmap_32.setPixelRef(device->getPixelRef());
bitmap_32.copyTo(&bitmap_16, SkBitmap::kARGB_4444_Config, &allocator);

[kaanb, 2013/09/06 02:05:54]

Apparently getPixelRef is protected not public, so cannot be called from here.
Also I need the PixelBuffer pointer here to pass to the IdentityAllocator
otherwise copyTo would copy over to some random place in heap and not into the
transfer buffer memory.

+    bitmap_32.setConfig(SkBitmap::kARGB_8888_Config,
+                        size.width(),
+                        size.height());
+    bitmap_32.allocPixels();

[reveman, 2013/09/05 16:24:17]

we shouldn't be allocating a temporary bitmap unless necessary. not clear this
code works at all with 32bpp resources. how is |buffer| modified in that case?

[kaanb, 2013/09/06 02:05:54]

Good point. Fixed.

+    SkBitmapDevice device_32(bitmap_32);
 
+    SkCanvas canvas(&device_32);
     skia::RefPtr<SkDrawFilter> draw_filter;
     switch (raster_mode_) {
       case LOW_QUALITY_RASTER_MODE:
@@ -149,14 +173,23 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
       picture_clone->RasterToBitmap(
           &canvas, content_rect_, contents_scale_, NULL);
     }
+
+    if (use_16bit_tiles_) {
+      SkBitmap bitmap_16;
+      IdentityAllocator allocator(buffer);
+      bitmap_32.copyTo(&bitmap_16, SkBitmap::kARGB_4444_Config, &allocator);

[enne (OOO), 2013/09/05 02:01:19]

Just to be clear, this is copying from the 8888 bitmap stored in buffer onto
buffer itself as a 4444 bitmap? Is that safe?

[Sami, 2013/09/05 14:13:26]

If I read this right we're copying from bitmap_32 (that was allocated storage on
line 135) to bitmap_16 which points to buffer. Tom and I think it should be
safe. Furthermore copyTo() internally uses a temporary allocation so you can
also copy from a bitmap to itself.

[kaanb, 2013/09/06 02:05:54]

Also, note that we want the destination of the buffer to be the PixelBuffer
allocated in ResourceProvider::AcquirePixelBuffer so we do the IdentityAllocator
trick.

[kaanb, 2013/09/06 02:05:54]

Actually 8888 bitmap uses temporary heap memory in this flow.

+    }
+
     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)
       OVERRIDE {
     RunAnalysisOnThread(thread_index);
-    return RunRasterOnThread(device, thread_index);
+    return RunRasterOnThread(thread_index, buffer, size);
   }
   virtual void CompleteOnOriginThread() OVERRIDE {
     reply_.Run(analysis_, !HasFinishedRunning() || WasCanceled());
@@ -189,6 +222,7 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
   int source_frame_number_;
   RenderingStatsInstrumentation* rendering_stats_;
   const RasterWorkerPool::RasterTask::Reply reply_;
+  bool use_16bit_tiles_;
 
   DISALLOW_COPY_AND_ASSIGN(RasterWorkerPoolTaskImpl);
 };
@@ -379,7 +413,8 @@ RasterWorkerPool::RasterTask RasterWorkerPool::CreateRasterTask(
     int source_frame_number,
     RenderingStatsInstrumentation* rendering_stats,
     const RasterTask::Reply& reply,
-    Task::Set* dependencies) {
+    Task::Set* dependencies,
+    bool use_16bit_tiles) {
   return RasterTask(
       new RasterWorkerPoolTaskImpl(resource,
                                    picture_pile,
@@ -393,7 +428,8 @@ RasterWorkerPool::RasterTask RasterWorkerPool::CreateRasterTask(
                                    source_frame_number,
                                    rendering_stats,
                                    reply,
-                                   &dependencies->tasks_));
+                                   &dependencies->tasks_,
+                                   use_16bit_tiles));
 }
 
 // static