Implement helper functionalities for computing image size with ES3 settings.

gpu/command_buffer/common/gles2_cmd_utils.h

Index: gpu/command_buffer/common/gles2_cmd_utils.h
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.h b/gpu/command_buffer/common/gles2_cmd_utils.h
index 3aa0299056a0fd83f1a4bf183e279e0af6b0d63e..90658d6fd02ef210ea1449d0abd82fb9652f048c 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.h
+++ b/gpu/command_buffer/common/gles2_cmd_utils.h
@@ -52,6 +52,24 @@ inline bool SafeAddInt32(int32_t a, int32_t b, int32_t* dst) {
   return checked.IsValid();
 }
 
+struct GLES2_UTILS_EXPORT PixelStoreParams {
+  PixelStoreParams()
+      : alignment(4),
+        row_length(0),
+        image_height(0),
+        skip_pixels(0),
+        skip_rows(0),
+        skip_images(0) {
+  }
+
+  int32_t alignment;
+  int32_t row_length;
+  int32_t image_height;
+  int32_t skip_pixels;
+  int32_t skip_rows;
+  int32_t skip_images;
+};
+
 // Utilties for GLES2 support.
 class GLES2_UTILS_EXPORT GLES2Util {
  public:
@@ -105,18 +123,26 @@ class GLES2_UTILS_EXPORT GLES2Util {
 
   // Computes the size of an image row including alignment padding
   static bool ComputeImagePaddedRowSize(
-      int width, int format, int type, int unpack_alignment,
+      int width, int format, int type, int alignment,
       uint32_t* padded_row_size);
 
   // Computes the size of image data for TexImage2D and TexSubImage2D.
-  // Optionally the unpadded and padded row sizes can be returned. If height < 2
-  // then the padded_row_size will be the same as the unpadded_row_size since
-  // padding is not necessary.
+  // Optionally the unpadded and padded row sizes can be returned.
   static bool ComputeImageDataSizes(
       int width, int height, int depth, int format, int type,
-      int unpack_alignment, uint32_t* size, uint32_t* unpadded_row_size,
+      int alignment, uint32_t* size, uint32_t* unpadded_row_size,
       uint32_t* padded_row_size);
 
+  // Similar to the above function, but taking into consideration all ES3
+  // pixel pack/unpack parameters.
+  // Optionally the skipped bytes in the beginning can be returned.

[Ken Russell (switch to Gerrit), 2015/12/09 00:05:50]

How are they optionally returned? All of the outgoing arguments appear to be
mandatory. Either the documentation should be updated or the arguments named
something like opt_skip_size.

Also, consider avoiding overloading ComputeImageDataSizes. Perhaps this one
should be ComputeImageDataSizesES3, or ideally, they could be merged.

[Zhenyao Mo, 2015/12/09 00:27:57]

They are optional in the sense they can be nullptr.  Switch name to opt*
Done

+  // Note the returned |size| does NOT include |skip_size|.
+  static bool ComputeImageDataSizes(
+      int width, int height, int depth, int format, int type,
+      const PixelStoreParams& params,
+      uint32_t* size, uint32_t* unpadded_row_size,
+      uint32_t* padded_row_size, uint32_t* skip_size);
+
   static size_t RenderbufferBytesPerPixel(int format);
 
   // Return the element's number of bytes.
@@ -192,6 +218,10 @@ class GLES2_UTILS_EXPORT GLES2Util {
   static std::string GetQualifiedEnumString(
       const EnumToString* table, size_t count, uint32_t value);
 
+  static bool ComputeImageRowSizeHelper(
+      int width, uint32 bytes_per_group, int alignment,
+      uint32* rt_unpadded_row_size, uint32* rt_padded_row_size);
+
   static const EnumToString* const enum_to_string_table_;
   static const size_t enum_to_string_table_len_;