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 aced03fcec6c8eb3c5e413d5213f8b635e3b756a..21c588c3311ee28cc1fa18b9f2813ccf074a44d3 100644
--- a/cc/resources/raster_worker_pool.cc
+++ b/cc/resources/raster_worker_pool.cc
@@ -48,7 +48,8 @@ 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 +61,8 @@ 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",
@@ -111,7 +113,6 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
         picture_pile_->GetCloneForDrawingOnThread(thread_index);
 
     SkCanvas canvas(device);
-
     skia::RefPtr<SkDrawFilter> draw_filter;
     switch (raster_mode_) {
       case LOW_QUALITY_RASTER_MODE:
@@ -149,6 +150,14 @@ class RasterWorkerPoolTaskImpl : public internal::RasterWorkerPoolTask {
       picture_clone->RasterToBitmap(
           &canvas, content_rect_, contents_scale_, NULL);
     }
+
+    if (use_16bit_tiles_) {
+      const SkBitmap& bitmap_32 = device->accessBitmap(true);
+      SkBitmap bitmap_16;
+      bitmap_32.copyTo(&bitmap_16, SkBitmap::kARGB_4444_Config);
+      canvas.drawBitmap(bitmap_16, 0, 0);

[Sami, 2013/08/08 10:11:01]

|canvas| is still a 32-bit bitmap so this is really just going from 32 => 16 =>
32 bits, i.e., throwing away precision :) I think we need to add a way to make
PixelBufferWorkerPoolTaskImpl give us a 16-bit device (which isn't supported by
Skia AFAIK).

[kaanb, 2013/08/08 17:25:05]

Let me check with Skia folks if they'd be willing to make a shortcut for us
here.

[bsalomon, 2013/08/08 18:40:15]

Hi, What's the intent here? Are you trying to go from a 16bit sw bitmap to a
16bit texture? bitmap_16 is a sw bitmap, is bitmap_32 a texture backed bitmap?

Also, I'm not sure how much it matters but it looks like accessBitmap() could
take false for the "changePixels" param since you are just reading from it.

+    }
+
     return true;
   }
 
@@ -189,6 +198,7 @@ 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 +389,8 @@ 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 +404,8 @@ RasterWorkerPool::RasterTask RasterWorkerPool::CreateRasterTask(
                                    source_frame_number,
                                    rendering_stats,
                                    reply,
-                                   &dependencies->tasks_));
+                                   &dependencies->tasks_,
+                                   use_16bit_tiles));
 }
 
 // static