Merge revision 643 and revision 648 changes:

- Improve the cefclient transparency test by adding the ability to view individual pixel values (issue #584).
- Change cefclient off-screen rendering example to account for premultiplied alpha values (issue #584).

git-svn-id: https://chromiumembedded.googlecode.com/svn/branches/1025@649 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

tests/cefclient/osrenderer.cpp

@@ -110,8 +110,8 @@ void ClientOSRenderer::Initialize() {
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 
   if (transparent_) {
-    // Alpha blending style.
-    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    // Alpha blending style. Texture values have premultiplied alpha.
+    glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
   }
 
   initialized_ = true;
@@ -355,6 +355,28 @@ void ClientOSRenderer::IncrementSpin(float spinDX, float spinDY) {
   spin_y_ -= spinDY;
 }
 
+bool ClientOSRenderer::GetPixelValue(int x, int y, unsigned char& r,
+                                     unsigned char& g, unsigned char& b,
+                                     unsigned char& a) {
+  if (!view_buffer_)
+    return false;
+
+  ASSERT(x >= 0 && x < view_width_);
+  ASSERT(y >= 0 && y < view_height_);
+                                       
+  int pixel_bytes = transparent_ ? 4 : 3;
+  int y_flipped = view_height_ - y;
+  int index = (view_width_ * y_flipped * pixel_bytes) + (x * pixel_bytes);
+
+  r = view_buffer_[index];
+  g = view_buffer_[index+1];
+  b = view_buffer_[index+2];
+  if (transparent_)
+    a = view_buffer_[index+3];
+
+  return true;
+}
+
 void ClientOSRenderer::SetBufferSize(int width, int height, bool view) {
   int dst_size = width * height * (transparent_?4:3);