Reland of Upgrade PixelStorei to ES3/WebGL2.

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 7a73f60c317584b4b2a328243d518055cbd290c8..c66f7d3da647911de2496b1857e0c2569c9f7161 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -85,6 +85,9 @@
       angle_pack_reverse_row_order_status_(kUnknownExtensionStatus),
       chromium_framebuffer_multisample_(kUnknownExtensionStatus),
       pack_alignment_(4),
+      pack_row_length_(0),
+      pack_skip_pixels_(0),
+      pack_skip_rows_(0),
       unpack_alignment_(4),
       unpack_row_length_(0),
       unpack_image_height_(0),
@@ -1717,32 +1720,41 @@
       << param << ")");
   switch (pname) {
     case GL_PACK_ALIGNMENT:
-        pack_alignment_ = param;
-        break;
+      pack_alignment_ = param;
+      break;
+    case GL_PACK_ROW_LENGTH:
+      pack_row_length_ = param;
+      break;
+    case GL_PACK_SKIP_PIXELS:
+      pack_skip_pixels_ = param;
+      break;
+    case GL_PACK_SKIP_ROWS:
+      pack_skip_rows_ = param;
+      break;
     case GL_UNPACK_ALIGNMENT:
-        unpack_alignment_ = param;
-        break;
+      unpack_alignment_ = param;
+      break;
     case GL_UNPACK_ROW_LENGTH_EXT:
-        unpack_row_length_ = param;
-        return;
+      unpack_row_length_ = param;
+      return;
     case GL_UNPACK_IMAGE_HEIGHT:
-        unpack_image_height_ = param;
-        return;
+      unpack_image_height_ = param;
+      return;
     case GL_UNPACK_SKIP_ROWS_EXT:
-        unpack_skip_rows_ = param;
-        return;
+      unpack_skip_rows_ = param;
+      return;
     case GL_UNPACK_SKIP_PIXELS_EXT:
-        unpack_skip_pixels_ = param;
-        return;
+      unpack_skip_pixels_ = param;
+      return;
     case GL_UNPACK_SKIP_IMAGES:
-        unpack_skip_images_ = param;
-        return;
+      unpack_skip_images_ = param;
+      return;
     case GL_PACK_REVERSE_ROW_ORDER_ANGLE:
-        pack_reverse_row_order_ =
-            IsAnglePackReverseRowOrderAvailable() ? (param != 0) : false;
-        break;
+      pack_reverse_row_order_ =
+          IsAnglePackReverseRowOrderAvailable() ? (param != 0) : false;
+      break;
     default:
-        break;
+      break;
   }
   helper_->PixelStorei(pname, param);
   CheckGLError();
@@ -3472,6 +3484,14 @@
     return;
   }
 
+  if (bound_pixel_pack_buffer_) {
+    // TODO(zmo): Need to handle the case of reading into a PIXEL_PACK_BUFFER
+    // in ES3. For now, generate a GL error.
+    SetGLError(GL_INVALID_OPERATION, "glReadPixels",
+               "ReadPixels to a pixel pack buffer isn't implemented");
+    return;
+  }
+
   if (bound_pixel_pack_transfer_buffer_id_) {
     GLuint offset = ToGLuint(pixels);
     BufferTracker::Buffer* buffer = GetBoundPixelUnpackTransferBufferIfValid(
@@ -3489,6 +3509,27 @@
   if (!pixels) {
     SetGLError(GL_INVALID_OPERATION, "glReadPixels", "pixels = NULL");
     return;
+  }
+
+  // compute the advance bytes per row for the dst pixels
+  uint32 dst_padded_row_size;
+  if (pack_row_length_ > 0) {
+    if (!GLES2Util::ComputeImagePaddedRowSize(
+        pack_row_length_, format, type, pack_alignment_,
+        &dst_padded_row_size)) {
+      SetGLError(
+          GL_INVALID_VALUE, "glReadPixels", "pack row length too large");
+      return;
+    }
+  } else {
+    dst_padded_row_size = padded_row_size;
+  }
+
+  // Advance pixels pointer past the skip rows and skip pixels
+  dest += pack_skip_rows_ * dst_padded_row_size;
+  if (pack_skip_pixels_) {
+    uint32 group_size = GLES2Util::ComputeImageGroupSize(format, type);
+    dest += pack_skip_pixels_ * group_size;
   }
 
   // Transfer by rows.
@@ -3521,7 +3562,7 @@
       // chunk.
       int8* rows_dst;
       if (pack_reverse_row_order_) {
-          rows_dst = dest + (height - num_rows) * padded_row_size;
+          rows_dst = dest + (height - num_rows) * dst_padded_row_size;
       } else {
           rows_dst = dest;
       }
@@ -3529,7 +3570,7 @@
       const int8* src = static_cast<const int8*>(buffer.address());
       for (GLint yy = 0; yy < num_rows; ++yy) {
         memcpy(rows_dst, src, unpadded_row_size);
-        rows_dst += padded_row_size;
+        rows_dst += dst_padded_row_size;
         src += padded_row_size;
       }
       if (!pack_reverse_row_order_) {