cc: Fix BytesPerPixel issue and refactor.

cc/resources/resource_format.cc

Index: cc/resources/resource_format.cc
diff --git a/cc/resources/resource_format.cc b/cc/resources/resource_format.cc
index 45581b800f140f3b6725a6bae4959686e66f03d0..8ddef5d617d1c8613e6beaa84992319b115b2378 100644
--- a/cc/resources/resource_format.cc
+++ b/cc/resources/resource_format.cc
@@ -4,6 +4,9 @@
 
 #include "cc/resources/resource_format.h"
 
+#include "third_party/khronos/GLES2/gl2.h"
+#include "third_party/khronos/GLES2/gl2ext.h"
+
 namespace cc {
 
 SkColorType ResourceFormatToSkColorType(ResourceFormat format) {
@@ -25,4 +28,57 @@ SkColorType ResourceFormatToSkColorType(ResourceFormat format) {
   return kN32_SkColorType;
 }
 
+int BitsPerPixel(ResourceFormat format) {
+  switch (format) {
+    case BGRA_8888:
+    case RGBA_8888:
+      return 32;
+    case RGBA_4444:
+    case RGB_565:
+      return 16;
+    case ALPHA_8:
+    case LUMINANCE_8:
+    case RED_8:
+      return 8;
+    case ETC1:
+      return 4;
+  }
+  NOTREACHED();
+  return 0;
+}
+
+GLenum GLDataType(ResourceFormat format) {
+  DCHECK_LE(format, RESOURCE_FORMAT_MAX);
+  static const GLenum format_gl_data_type[RESOURCE_FORMAT_MAX + 1] = {

[ericrk, 2015/07/24 20:03:52]

There's actually no warning/error generated if you underfill this array (if
RESOURCE_FORMAT_MAX increases).

One alternative that might be safer is:

static const GLenum format_gl_data_type[] = {...};
static_assert(arraysize(format_gl_data_type) == RESOURCE_FORMAT_MAX + 1,
"format_gl_data_type does not handle all cases.");

or something like that. same below.

[prashant.n, 2015/07/25 07:15:43]

Sounds good. I'll incorporate this.

+      GL_UNSIGNED_BYTE,           // RGBA_8888
+      GL_UNSIGNED_SHORT_4_4_4_4,  // RGBA_4444
+      GL_UNSIGNED_BYTE,           // BGRA_8888
+      GL_UNSIGNED_BYTE,           // ALPHA_8
+      GL_UNSIGNED_BYTE,           // LUMINANCE_8
+      GL_UNSIGNED_SHORT_5_6_5,    // RGB_565,
+      GL_UNSIGNED_BYTE,           // ETC1
+      GL_UNSIGNED_BYTE            // RED_8
+  };
+  return format_gl_data_type[format];
+}
+
+GLenum GLDataFormat(ResourceFormat format) {
+  DCHECK_LE(format, RESOURCE_FORMAT_MAX);
+  static const GLenum format_gl_data_format[RESOURCE_FORMAT_MAX + 1] = {
+      GL_RGBA,           // RGBA_8888
+      GL_RGBA,           // RGBA_4444
+      GL_BGRA_EXT,       // BGRA_8888
+      GL_ALPHA,          // ALPHA_8
+      GL_LUMINANCE,      // LUMINANCE_8
+      GL_RGB,            // RGB_565
+      GL_ETC1_RGB8_OES,  // ETC1
+      GL_RED_EXT         // RED_8
+  };
+  return format_gl_data_format[format];
+}
+
+GLenum GLInternalFormat(ResourceFormat format) {
+  return GLDataFormat(format);
+}
+
 }  // namespace cc