cc: TextureUploader - Reset GL_UNPACK_ALIGNMENT to 4 before uploading images.

cc/resources/texture_uploader.cc

 // 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 "cc/resources/texture_uploader.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/debug/trace_event.h"
@@ skipping 178 matching lines @@
   if (source_rect.IsEmpty())
     return;
   DCHECK(image);
 
   // Offset from image-rect to source-rect.
   gfx::Vector2d offset(source_rect.origin() - image_rect.origin());
 
   const uint8* pixel_source;
   unsigned bytes_per_pixel = BitsPerPixel(format) / 8;
   // Use 4-byte row alignment (OpenGL default) for upload performance.
-  // Assuming that GL_UNPACK_ALIGNMENT has not changed from default.
+  // Assuming that GL_UNPACK_ALIGNMENT = 4 is set in UploadWithMapTexSubImage.
   unsigned upload_image_stride =
       RoundUp(bytes_per_pixel * source_rect.width(), 4u);
 
   if (upload_image_stride == image_rect.width() * bytes_per_pixel &&
       !offset.x()) {
     pixel_source = &image[image_rect.width() * bytes_per_pixel * offset.y()];
   } else {
     size_t needed_size = upload_image_stride * source_rect.height();
     if (sub_image_size_ < needed_size) {
       sub_image_.reset(new uint8[needed_size]);
@@ skipping 34 matching lines @@
     return;
   DCHECK(image);
   // Compressed textures have no implementation of mapTexSubImage.
   DCHECK_NE(ETC1, format);
 
   // Offset from image-rect to source-rect.
   gfx::Vector2d offset(source_rect.origin() - image_rect.origin());
 
   unsigned bytes_per_pixel = BitsPerPixel(format) / 8;
   // Use 4-byte row alignment (OpenGL default) for upload performance.
-  // Assuming that GL_UNPACK_ALIGNMENT has not changed from default.
+  gl_->PixelStorei(GL_UNPACK_ALIGNMENT, 4);

[danakj, 2014/12/19 20:00:46]

Should we do this when we take control of the context back from ganesh instead
of doing it on every upload? Like we do in GLRenderer:
https://code.google.com/p/chromium/codesearch#chromium/src/cc/output/gl_rende...

[vmiura, 2014/12/19 21:28:16]

If there's a good spot we could do that.

Discussing a bit with Vangelis, we were thinking that as the PixelStorei() call
is not costly compared to actually transferring a texture, then we could put it
here and not be concerned about other code that may inadvertently modify the
state.

   unsigned upload_image_stride =
       RoundUp(bytes_per_pixel * source_rect.width(), 4u);
 
   // Upload tile data via a mapped transfer buffer
   uint8* pixel_dest =
       static_cast<uint8*>(gl_->MapTexSubImage2DCHROMIUM(GL_TEXTURE_2D,
                                                         0,
                                                         dest_offset.x(),
                                                         dest_offset.y(),
                                                         source_rect.width(),
@@ skipping 64 matching lines @@
       textures_per_second_history_.erase(textures_per_second_history_.begin());
       textures_per_second_history_.erase(--textures_per_second_history_.end());
     }
     textures_per_second_history_.insert(textures_per_second);
 
     available_queries_.push_back(pending_queries_.take_front());
   }
 }
 
 }  // namespace cc