Addition of unpremultiply setting to GL_CHROMIUM_copy_texture.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
===================================================================
--- gpu/command_buffer/service/gles2_cmd_decoder.cc	(revision 141671)
+++ gpu/command_buffer/service/gles2_cmd_decoder.cc	(working copy)
@@ -1388,8 +1388,9 @@
   // unpack flip y as last set by glPixelStorei
   bool unpack_flip_y_;
 
-  // unpack premultiply alpha as last set by glPixelStorei
+  // unpack (un)premultiply alpha as last set by glPixelStorei
   bool unpack_premultiply_alpha_;
+  bool unpack_unpremultiply_alpha_;
 
   // The currently bound array buffer. If this is 0 it is illegal to call
   // glVertexAttribPointer.
@@ -1904,6 +1905,7 @@
       unpack_alignment_(4),
       unpack_flip_y_(false),
       unpack_premultiply_alpha_(false),
+      unpack_unpremultiply_alpha_(false),
       attrib_0_buffer_id_(0),
       attrib_0_buffer_matches_value_(true),
       attrib_0_size_(0),
@@ -6364,7 +6366,14 @@
         return error::kNoError;
     case GL_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM:

[greggman, 2012/06/15 00:11:45]

When you add a new type here you also need to add a new type to
GLES2DecoderImpl::GetHelper and also the GLState list in
build_gles2_cmd_buffer.py

Did we forget the previous ones?

Should probably add a test

[Jeff Timanus, 2012/06/18 14:50:24]

I think a few settings are missing from GetHelper:
GL_UNPACK_FLIP_Y_CHROMIUM
GL_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM
GL_PACK_REVERSE_ROW_ORDER_ANGLE

These are also missing from the GLState list.

Adding them.

         unpack_premultiply_alpha_ = (param != 0);
+        unpack_unpremultiply_alpha_ =

[greggman, 2012/06/15 00:11:45]

This logic seems strange to me. 

If I go pre=1, un=1, un=0 now pre = 0 but I, as a user, never explicitly set it
to 0

Do you want to just set to the 2 flags here and decide which takes precedence
when you apply them?

[Jeff Timanus, 2012/06/18 14:50:24]

Yeah, I mulled how to best handle this situation.  Maybe the simplest (and most
obvious) solution would be set the precedence such that if both are enabled,
then they nullify each other.

+            unpack_unpremultiply_alpha_ && !unpack_premultiply_alpha_;
         return error::kNoError;
+    case GL_UNPACK_UNPREMULTIPLY_ALPHA_CHROMIUM:
+        unpack_unpremultiply_alpha_ = (param != 0);
+        unpack_premultiply_alpha_ =
+            unpack_premultiply_alpha_ && !unpack_unpremultiply_alpha_;
+        return error::kNoError;
     default:
         break;
   }
@@ -8825,7 +8834,8 @@
   copy_texture_CHROMIUM_->DoCopyTexture(target, source_info->service_id(),
                                         dest_info->service_id(), level,
                                         unpack_flip_y_,
-                                        unpack_premultiply_alpha_);
+                                        unpack_premultiply_alpha_,
+                                        unpack_unpremultiply_alpha_);
   glViewport(viewport_x_, viewport_y_, viewport_width_, viewport_height_);
 
   // Restore all of the state touched by the extension.