Implement transform/clip support for Android WebView.

content/renderer/android/synchronous_compositor_output_surface.cc

Index: content/renderer/android/synchronous_compositor_output_surface.cc
diff --git a/content/renderer/android/synchronous_compositor_output_surface.cc b/content/renderer/android/synchronous_compositor_output_surface.cc
index 7acdf8a31b62e13e82872e3c2fdafe87a418f4b1..7ba9b364ec16c3a359ebc6d3ef0c0eaccf4bef2c 100644
--- a/content/renderer/android/synchronous_compositor_output_surface.cc
+++ b/content/renderer/android/synchronous_compositor_output_surface.cc
@@ -153,50 +153,58 @@ bool SynchronousCompositorOutputSurface::IsHwReady() {
   return context3d() != NULL;
 }
 
+static gfx::Transform adjustTransformForClip(gfx::Transform transform,

[joth, 2013/05/25 02:56:40]

nits:

prefer namespace {} to static functions.

capitalize: AdjustTransformForClip()

cont& for transform

maybe comment why we need to remove the clip origin?

+                                             gfx::Rect clip) {
+  transform.matrix().postTranslate(-clip.x(), -clip.y(), 0);
+  return transform;
+}
+
 bool SynchronousCompositorOutputSurface::DemandDrawSw(SkCanvas* canvas) {
   DCHECK(CalledOnValidThread());
   DCHECK(canvas);
   DCHECK(!current_sw_canvas_);
   current_sw_canvas_ = canvas;
 
-  SkRect canvas_clip;
-  gfx::Rect damage_area;
-  if (canvas->getClipBounds(&canvas_clip)) {
-    damage_area = gfx::ToEnclosedRect(gfx::SkRectToRectF(canvas_clip));
-  } else {
-    damage_area = gfx::Rect(kint16max, kint16max);
-  }
+  SkIRect canvas_clip;
+  canvas->getClipDeviceBounds(&canvas_clip);
+  gfx::Rect clip = gfx::SkIRectToRect(canvas_clip);
 
-  gfx::Transform transform;
+  gfx::Transform transform(gfx::Transform::kSkipInitialization);
   transform.matrix() = canvas->getTotalMatrix();  // Converts 3x3 matrix to 4x4.
 
-  InvokeComposite(transform, damage_area);
+  client_->SetDeviceTransformAndClip(adjustTransformForClip(transform, clip),
+                                     clip);
+  InvokeComposite(clip);
 
   bool finished_draw = current_sw_canvas_ == NULL;
   current_sw_canvas_ = NULL;
   return finished_draw;
 }
 
+static gfx::Rect clipFlipY(gfx::Rect clip, gfx::Size view_size) {

[joth, 2013/05/25 02:56:40]

ditto - namespace {} / capitalize

+  clip.set_y(view_size.height() - clip.bottom());
+  return clip;
+}
+
 bool SynchronousCompositorOutputSurface::DemandDrawHw(
       gfx::Size view_size,
       const gfx::Transform& transform,
-      gfx::Rect damage_area) {
+      gfx::Rect clip) {
   DCHECK(CalledOnValidThread());
   DCHECK(client_);
 
   did_swap_buffer_ = false;
 
-  InvokeComposite(transform, damage_area);
+  client_->SetDeviceTransformAndClip(adjustTransformForClip(transform, clip),
+                                     clipFlipY(clip, view_size));

[joth, 2013/05/25 02:56:40]

any idea why we do need to flip Y for clip (in HW mode only) but not for the
SetNeedsRedrawRect() call that follows it?

+  InvokeComposite(clip);
 
   return did_swap_buffer_;
 }
 
 void SynchronousCompositorOutputSurface::InvokeComposite(
-    const gfx::Transform& transform,
     gfx::Rect damage_area) {
-  // TODO(boliu): This assumes |transform| is identity and |damage_area| is the
-  // whole view. Tracking bug to implement this: crbug.com/230463.
-  client_->SetNeedsRedrawRect(damage_area);
+  client_->SetNeedsRedrawRect(gfx::Rect(damage_area.size()));
   if (needs_begin_frame_)
     client_->BeginFrame(base::TimeTicks::Now());
 }