cc: Adding support for RGBA_4444 tile textures

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 6d6ac9d839871002e9facb7e84546a56bd32be29..d78875755fd96de8753dc0ad81a53ca753c977d6 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -7,6 +7,10 @@
 #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"
@@ -685,7 +689,13 @@ ResourceProvider::ResourceProvider(OutputSurface* output_surface,
       use_texture_usage_hint_(false),
       use_shallow_flush_(false),
       max_texture_size_(0),
-      best_texture_format_(0) {}
+      best_texture_format_(0),
+      use_16bit_textures_(false) {
+#if defined(OS_ANDROID)
+    if (base::android::SysUtils::IsLowEndDevice())
+      use_16bit_textures_ = true;
+#endif
+}
 
 void ResourceProvider::InitializeSoftware() {
   DCHECK(thread_checker_.CalledOnValidThread());
@@ -1175,6 +1185,8 @@ void ResourceProvider::BeginSetPixels(ResourceId id) {
     context3d->beginQueryEXT(
         GL_ASYNC_PIXEL_TRANSFERS_COMPLETED_CHROMIUM,
         resource->gl_upload_query_id);
+    GLenum texture_data_type = use_16bit_textures_
+        ? GL_UNSIGNED_SHORT_4_4_4_4 : GL_UNSIGNED_BYTE;
     if (allocate) {
       context3d->asyncTexImage2DCHROMIUM(GL_TEXTURE_2D,
                                          0, /* level */
@@ -1183,7 +1195,7 @@ void ResourceProvider::BeginSetPixels(ResourceId id) {
                                          resource->size.height(),
                                          0, /* border */
                                          resource->format,
-                                         GL_UNSIGNED_BYTE,
+                                         texture_data_type,
                                          NULL);
     } else {
       context3d->asyncTexSubImage2DCHROMIUM(GL_TEXTURE_2D,
@@ -1193,7 +1205,7 @@ void ResourceProvider::BeginSetPixels(ResourceId id) {
                                             resource->size.width(),
                                             resource->size.height(),
                                             resource->format,
-                                            GL_UNSIGNED_BYTE,
+                                            texture_data_type,
                                             NULL);
     }
     context3d->endQueryEXT(GL_ASYNC_PIXEL_TRANSFERS_COMPLETED_CHROMIUM);
@@ -1316,6 +1328,8 @@ void ResourceProvider::LazyAllocate(Resource* resource) {
                                               size.width(),
                                               size.height()));
   } else {
+    GLenum texture_data_type = use_16bit_textures_
+        ? GL_UNSIGNED_SHORT_4_4_4_4 : GL_UNSIGNED_BYTE;
     GLC(context3d, context3d->texImage2D(GL_TEXTURE_2D,
                                          0,
                                          format,
@@ -1323,7 +1337,7 @@ void ResourceProvider::LazyAllocate(Resource* resource) {
                                          size.height(),
                                          0,
                                          format,
-                                         GL_UNSIGNED_BYTE,
+                                         texture_data_type,

[Sami, 2013/08/08 10:11:01]

This parameter only sets the format of the data that is passed into
glTexImage2D. To set the format of the texture itself, we need to set |format|
to RGBA4_OES. Probably the best way to do that is to initialize
best_texture_format_ to RGBA4_OES.

There are also a bunch of assumptions in ResourceProvider that sizeof(pixel) ==
4 which we'd need to fix.

[kaanb, 2013/08/08 17:25:05]

See the comment on RGBA4_OES above.

                                          NULL));
   }
 }