Support copying a partial rectangle region from the compositing surface on Mac.

content/browser/renderer_host/compositing_iosurface_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/compositing_iosurface_mac.h"
 
 #include <OpenGL/OpenGL.h>
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 #include "content/public/browser/browser_thread.h"
 #include "gpu/command_buffer/service/gpu_switches.h"
+#include "ui/gfx/rect.h"
 #include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_switches.h"
 #include "ui/surface/io_surface_support_mac.h"
 
 #ifdef NDEBUG
 #define CHECK_GL_ERROR()
 #else
 #define CHECK_GL_ERROR() do {                                           \
     GLenum gl_error = glGetError();                                     \
@@ skipping 271 matching lines @@
     // by forcing the graphics pipeline to be completely drained at this
     // point.
     glFinish();
   }
 
   CGLFlushDrawable(cglContext_);
 
   CGLSetCurrentContext(0);
 }
 
-bool CompositingIOSurfaceMac::CopyTo(const gfx::Size& dst_size, void* out) {
+bool CompositingIOSurfaceMac::CopyTo(
+      const gfx::Rect& src_subrect,
+      const gfx::Size& dst_size,

[Nico, 2012/07/26 23:45:48]

Can you call the parameters src_pixel_subrect and dst_pixel_size?

[mazda, 2012/07/27 00:00:35]

Done.

+      void* out) {
   if (!MapIOSurfaceToTexture(io_surface_handle_))
     return false;
 
   CGLSetCurrentContext(cglContext_);
   GLuint target = GL_TEXTURE_RECTANGLE_ARB;
 
   GLuint dst_texture = 0;
   glGenTextures(1, &dst_texture); CHECK_GL_ERROR();
   glBindTexture(target, dst_texture); CHECK_GL_ERROR();
 
@@ skipping 29 matching lines @@
   glDisable(GL_BLEND);
 
   glUseProgram(shader_program_blit_rgb_);
 
   int texture_unit = 0;
   glUniform1i(blit_rgb_sampler_location_, texture_unit);
   glActiveTexture(GL_TEXTURE0 + texture_unit);
   glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texture_);
 
   SurfaceQuad quad;
-  quad.set_size(dst_size, pixel_io_surface_size_);
+  quad.set_rect(0.0f, 0.0f, dst_size.width(), dst_size.height());
+  quad.set_texcoord_rect(src_subrect.x(), src_subrect.y(),
+                         src_subrect.right(), src_subrect.bottom());
   DrawQuad(quad);
 
   glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0); CHECK_GL_ERROR();
   glUseProgram(0);
 
   CGLFlushDrawable(cglContext_);
 
   glReadPixels(0, 0, dst_size.width(), dst_size.height(),
                GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, out);
 
@@ skipping 94 matching lines @@
 void CompositingIOSurfaceMac::GlobalFrameDidChange() {
   [glContext_ update];
 }
 
 void CompositingIOSurfaceMac::ClearDrawable() {
   [glContext_ clearDrawable];
   UnrefIOSurface();
 }
 
 }  // namespace content