Fix content scaling bug on Mac

content/common/gpu/image_transport_surface_fbo_mac.mm

 // Copyright 2014 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/common/gpu/image_transport_surface_fbo_mac.h"
 
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/gpu/image_transport_surface_calayer_mac.h"
 #include "content/common/gpu/image_transport_surface_iosurface_mac.h"
 #include "ui/base/cocoa/remote_layer_api.h"
@@ skipping 57 matching lines @@
 bool ImageTransportSurfaceFBO::IsOffscreen() {
   return false;
 }
 
 bool ImageTransportSurfaceFBO::OnMakeCurrent(gfx::GLContext* context) {
   context_ = context;
 
   if (made_current_)
     return true;
 
-  OnResize(gfx::Size(1, 1), 1.f);
+  AllocateOrResizeFramebuffer(gfx::Size(1, 1), 1.f);
 
   made_current_ = true;
   return true;
 }
 
 unsigned int ImageTransportSurfaceFBO::GetBackingFrameBufferObject() {
   return fbo_id_;
 }
 
 bool ImageTransportSurfaceFBO::SetBackbufferAllocation(bool allocation) {
@@ skipping 14 matching lines @@
 }
 
 void ImageTransportSurfaceFBO::AdjustBufferAllocation() {
   // On mac, the frontbuffer and backbuffer are the same buffer. The buffer is
   // free'd when both the browser and gpu processes have Unref'd the IOSurface.
   if (!backbuffer_suggested_allocation_ &&
       !frontbuffer_suggested_allocation_ &&
       has_complete_framebuffer_) {
     DestroyFramebuffer();
   } else if (backbuffer_suggested_allocation_ && !has_complete_framebuffer_) {
-    CreateFramebuffer();
+    AllocateOrResizeFramebuffer(pixel_size_, scale_factor_);
   }
 }
 
 bool ImageTransportSurfaceFBO::SwapBuffers() {
   DCHECK(backbuffer_suggested_allocation_);
   if (!frontbuffer_suggested_allocation_)
     return true;
   glFlush();
 
   // It is the responsibility of the storage provider to send the swap IPC.
   is_swap_buffers_send_pending_ = true;
-  storage_provider_->SwapBuffers(size_, scale_factor_);
+  storage_provider_->SwapBuffers(pixel_size_, scale_factor_);
   return true;
 }
 
 void ImageTransportSurfaceFBO::SendSwapBuffers(uint64 surface_handle,
                                                const gfx::Size pixel_size,
                                                float scale_factor) {
   GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params params;
   params.surface_handle = surface_handle;
   params.size = pixel_size;
   params.scale_factor = scale_factor;
@@ skipping 12 matching lines @@
   // Mac does not support sub-buffer swaps.
   NOTREACHED();
   return false;
 }
 
 bool ImageTransportSurfaceFBO::SupportsPostSubBuffer() {
   return true;
 }
 
 gfx::Size ImageTransportSurfaceFBO::GetSize() {
-  return size_;
+  return pixel_size_;
 }
 
 void* ImageTransportSurfaceFBO::GetHandle() {
   return NULL;
 }
 
 void* ImageTransportSurfaceFBO::GetDisplay() {
   return NULL;
 }
 
 void ImageTransportSurfaceFBO::OnBufferPresented(
     const AcceleratedSurfaceMsg_BufferPresented_Params& params) {
   SetRendererID(params.renderer_id);
   storage_provider_->SwapBuffersAckedByBrowser(params.disable_throttling);
 }
 
-void ImageTransportSurfaceFBO::OnResize(gfx::Size size,
+void ImageTransportSurfaceFBO::OnResize(gfx::Size pixel_size,
                                         float scale_factor) {
   TRACE_EVENT2("gpu", "ImageTransportSurfaceFBO::OnResize",
-               "old_width", size_.width(), "new_width", size.width());
+               "old_size", pixel_size_.ToString(),
+               "new_size", pixel_size.ToString());
   // Caching |context_| from OnMakeCurrent. It should still be current.
   DCHECK(context_->IsCurrent(this));
 
-  size_ = size;
-  scale_factor_ = scale_factor;
-
-  CreateFramebuffer();
+  AllocateOrResizeFramebuffer(pixel_size, scale_factor);
 }
 
 void ImageTransportSurfaceFBO::SetLatencyInfo(
     const std::vector<ui::LatencyInfo>& latency_info) {
   for (size_t i = 0; i < latency_info.size(); i++)
     latency_info_.push_back(latency_info[i]);
 }
 
 void ImageTransportSurfaceFBO::WakeUpGpu() {
   NOTIMPLEMENTED();
@@ skipping 26 matching lines @@
   if (depth_stencil_renderbuffer_id_) {
     glDeleteRenderbuffersEXT(1, &depth_stencil_renderbuffer_id_);
     depth_stencil_renderbuffer_id_ = 0;
   }
 
   storage_provider_->FreeColorBufferStorage();
 
   has_complete_framebuffer_ = false;
 }
 
-void ImageTransportSurfaceFBO::CreateFramebuffer() {
-  gfx::Size new_rounded_size = storage_provider_->GetRoundedSize(size_);
+void ImageTransportSurfaceFBO::AllocateOrResizeFramebuffer(
+    const gfx::Size& new_pixel_size, float new_scale_factor) {
+  gfx::Size new_rounded_pixel_size =
+      storage_provider_->GetRoundedSize(new_pixel_size);
 
-  // Only recreate surface when the rounded up size has changed.
-  if (has_complete_framebuffer_ && new_rounded_size == rounded_size_)
+  // Only recreate the surface's storage when the rounded up size has changed,
+  // or the scale factor has changed.
+  bool needs_new_storage =
+      !has_complete_framebuffer_ ||
+      new_rounded_pixel_size != rounded_pixel_size_ ||
+      new_scale_factor != scale_factor_;
+
+  // Save the new storage parameters.
+  pixel_size_ = new_pixel_size;
+  rounded_pixel_size_ = new_rounded_pixel_size;
+  scale_factor_ = new_scale_factor;
+
+  if (!needs_new_storage)
     return;
 
-  TRACE_EVENT2("gpu", "ImageTransportSurfaceFBO::CreateFramebuffer",
-               "width", new_rounded_size.width(),
-               "height", new_rounded_size.height());
-
-  rounded_size_ = new_rounded_size;
+  TRACE_EVENT2("gpu", "ImageTransportSurfaceFBO::AllocateOrResizeFramebuffer",
+               "width", new_rounded_pixel_size.width(),
+               "height", new_rounded_pixel_size.height());
 
   // GL_TEXTURE_RECTANGLE_ARB is the best supported render target on
   // Mac OS X and is required for IOSurface interoperability.
   GLint previous_texture_id = 0;
   glGetIntegerv(GL_TEXTURE_BINDING_RECTANGLE_ARB, &previous_texture_id);
 
   // Free the old IO Surface first to reduce memory fragmentation.
   DestroyFramebuffer();
 
   glGenFramebuffersEXT(1, &fbo_id_);
@@ skipping 25 matching lines @@
     bool has_packed_depth_stencil =
          GLSurface::ExtensionsContain(
              reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS)),
                                             "GL_EXT_packed_depth_stencil");
 
     if (has_packed_depth_stencil) {
       glGenRenderbuffersEXT(1, &depth_stencil_renderbuffer_id_);
       glBindRenderbufferEXT(GL_RENDERBUFFER_EXT,
                             depth_stencil_renderbuffer_id_);
       glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH24_STENCIL8_EXT,
-                              rounded_size_.width(), rounded_size_.height());
+                              rounded_pixel_size_.width(),
+                              rounded_pixel_size_.height());
       glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT,
                                   GL_STENCIL_ATTACHMENT_EXT,
                                   GL_RENDERBUFFER_EXT,
                                   depth_stencil_renderbuffer_id_);
     }
 
     // If we asked for stencil but the extension isn't present,
     // it's OK to silently fail; subsequent code will/must check
     // for the presence of a stencil buffer before attempting to
     // do stencil-based operations.
   }
 
   bool allocated_color_buffer = storage_provider_->AllocateColorBufferStorage(
       static_cast<CGLContextObj>(context_->GetHandle()), texture_id_,
-      rounded_size_, scale_factor_);
+      rounded_pixel_size_, scale_factor_);
   if (!allocated_color_buffer) {
     DLOG(ERROR) << "Failed to allocate color buffer storage.";
     DestroyFramebuffer();
     return;
   }
 
   GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
   if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
     DLOG(ERROR) << "Framebuffer was incomplete: " << status;
     DestroyFramebuffer();
     return;
   }
 
   has_complete_framebuffer_ = true;
 
   glBindTexture(GL_TEXTURE_RECTANGLE_ARB, previous_texture_id);
   // The FBO remains bound for this GL context.
 }
 
 }  // namespace content