cc: Adding support for RGBA_4444 tile textures

cc/resources/resource_provider.cc

 // Copyright 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 "cc/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
+#if defined(OS_ANDROID)
+#include "base/android/sys_utils.h"
+#endif
+
 #include "base/containers/hash_tables.h"
 #include "base/debug/alias.h"
 #include "base/stl_util.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "cc/output/gl_renderer.h"  // For the GLC() macro.
 #include "cc/resources/platform_color.h"
 #include "cc/resources/returned_resource.h"
 #include "cc/resources/transferable_resource.h"
 #include "cc/scheduler/texture_uploader.h"
@@ skipping 654 matching lines @@
     : output_surface_(output_surface),
       lost_output_surface_(false),
       highp_threshold_min_(highp_threshold_min),
       next_id_(1),
       next_child_(1),
       default_resource_type_(InvalidType),
       use_texture_storage_ext_(false),
       use_texture_usage_hint_(false),
       use_shallow_flush_(false),
       max_texture_size_(0),
-      best_texture_format_(0) {
+      best_texture_format_(0),

[epennerAtGoogle, 2013/09/05 01:54:15]

Could we have best_texture_type in addition to best_texture_format, and avoid
any #ifdefs/booleans?

[kaanb, 2013/09/06 02:05:54]

Done.

+      use_16_bit_textures_(false) {
   DCHECK(output_surface_->HasClient());
+#if defined(OS_ANDROID)
+  if (base::android::SysUtils::IsLowEndDevice())
+    use_16_bit_textures_ = true;

[enne (OOO), 2013/09/05 02:01:19]

Please make this a LayerTreeSetting and keep the #ifdef out of cc so that this
setting can be tested in a device-independent manner.

[kaanb, 2013/09/06 02:05:54]

Done.

+#endif
 }
 
 void ResourceProvider::InitializeSoftware() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(Bitmap, default_resource_type_);
 
   CleanUpGLIfNeeded();
 
   default_resource_type_ = Bitmap;
   max_texture_size_ = INT_MAX / 2;
@@ skipping 16 matching lines @@
   const ContextProvider::Capabilities& caps =
       output_surface_->context_provider()->ContextCapabilities();
 
   bool use_map_sub = caps.map_sub;
   bool use_bgra = caps.texture_format_bgra8888;
   use_texture_storage_ext_ = caps.texture_storage;
   use_shallow_flush_ = caps.shallow_flush;
   use_texture_usage_hint_ = caps.texture_usage;
 
   texture_uploader_ =
-      TextureUploader::Create(context3d, use_map_sub, use_shallow_flush_);
+      TextureUploader::Create(context3d,
+                              use_map_sub,
+                              use_shallow_flush_,
+                              use_16_bit_textures_);
   GLC(context3d, context3d->getIntegerv(GL_MAX_TEXTURE_SIZE,
                                         &max_texture_size_));
   best_texture_format_ = PlatformColor::BestTextureFormat(use_bgra);
 
   return true;
 }
 
 void ResourceProvider::CleanUpGLIfNeeded() {
   WebGraphicsContext3D* context3d = Context3d();
   if (default_resource_type_ != GLTexture) {
@@ skipping 235 matching lines @@
   DCHECK(!resource->image_id);
 
   if (resource->type == GLTexture) {
     WebGraphicsContext3D* context3d = Context3d();
     DCHECK(context3d);
     if (!resource->gl_pixel_buffer_id)
       resource->gl_pixel_buffer_id = context3d->createBuffer();
     context3d->bindBuffer(
         GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM,
         resource->gl_pixel_buffer_id);
+    size_t bytes_per_pixel = use_16_bit_textures_ ? 2 : 4;
     context3d->bufferData(
         GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM,
-        4 * resource->size.GetArea(),
+        bytes_per_pixel * resource->size.GetArea(),
         NULL,
         GL_DYNAMIC_DRAW);
     context3d->bindBuffer(GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM, 0);
   }
 
   if (resource->pixels) {
     if (resource->pixel_buffer)
       return;
 
     resource->pixel_buffer = new uint8_t[4 * resource->size.GetArea()];
@@ skipping 161 matching lines @@
     DCHECK(resource->gl_pixel_buffer_id);
     context3d->bindTexture(GL_TEXTURE_2D, resource->gl_id);
     context3d->bindBuffer(
         GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM,
         resource->gl_pixel_buffer_id);
     if (!resource->gl_upload_query_id)
       resource->gl_upload_query_id = context3d->createQueryEXT();
     context3d->beginQueryEXT(
         GL_ASYNC_PIXEL_UNPACK_COMPLETED_CHROMIUM,
         resource->gl_upload_query_id);
+    GLenum texture_data_type = use_16_bit_textures_

[enne (OOO), 2013/09/05 02:01:19]

Rather than having to pass around booleans and settings that force every texture
into one mode or the other, can resources just have a texture_data_type value? 
Maybe there could just be a LayerTreeSetting for preferred texture_data_type and
ResourceProvider could try to respect that when generating resources.

That way you could (potentially) have two different formats at once and cc gets
a feature rather than a mode.

[kaanb, 2013/09/06 02:05:54]

Great point, I didn't have time for it today. I'll look into it tomorrow.

+        ? GL_UNSIGNED_SHORT_4_4_4_4 : GL_UNSIGNED_BYTE;
     if (allocate) {
       context3d->asyncTexImage2DCHROMIUM(GL_TEXTURE_2D,
                                          0, /* level */
                                          resource->format,
                                          resource->size.width(),
                                          resource->size.height(),
                                          0, /* border */
                                          resource->format,
-                                         GL_UNSIGNED_BYTE,
+                                         texture_data_type,
                                          NULL);
     } else {
       context3d->asyncTexSubImage2DCHROMIUM(GL_TEXTURE_2D,
                                             0, /* level */
                                             0, /* x */
                                             0, /* y */
                                             resource->size.width(),
                                             resource->size.height(),
                                             resource->format,
-                                            GL_UNSIGNED_BYTE,
+                                            texture_data_type,
                                             NULL);
     }
     context3d->endQueryEXT(GL_ASYNC_PIXEL_UNPACK_COMPLETED_CHROMIUM);
     context3d->bindBuffer(GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM, 0);
   }
 
   if (resource->pixels) {
     DCHECK(!resource->mailbox.IsValid());
     DCHECK(resource->pixel_buffer);
     DCHECK(resource->format == GL_RGBA);
@@ skipping 90 matching lines @@
   GLenum format = resource->format;
   GLC(context3d, context3d->bindTexture(GL_TEXTURE_2D, resource->gl_id));
   if (use_texture_storage_ext_ && IsTextureFormatSupportedForStorage(format)) {
     GLenum storage_format = TextureToStorageFormat(format);
     GLC(context3d, context3d->texStorage2DEXT(GL_TEXTURE_2D,
                                               1,
                                               storage_format,
                                               size.width(),
                                               size.height()));
   } else {
+    GLenum texture_data_type = use_16_bit_textures_
+        ? GL_UNSIGNED_SHORT_4_4_4_4 : GL_UNSIGNED_BYTE;
     GLC(context3d, context3d->texImage2D(GL_TEXTURE_2D,
                                          0,
                                          format,
                                          size.width(),
                                          size.height(),
                                          0,
                                          format,
-                                         GL_UNSIGNED_BYTE,
+                                         texture_data_type,
                                          NULL));
   }
 }
 
 void ResourceProvider::EnableReadLockFences(ResourceProvider::ResourceId id,
                                             bool enable) {
   Resource* resource = GetResource(id);
   resource->enable_read_lock_fences = enable;
 }
 
@@ skipping 85 matching lines @@
   context->getIntegerv(GL_ACTIVE_TEXTURE, &active_unit);
   return active_unit;
 }
 
 WebKit::WebGraphicsContext3D* ResourceProvider::Context3d() const {
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->Context3d() : NULL;
 }
 
 }  // namespace cc