Improve Ganesh helpers.

mojo/skia/ganesh_helpers.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/skia/ganesh_helpers.h"
+
+#include <GLES2/gl2.h>
+
+#include "base/logging.h"
+#include "third_party/skia/include/core/SkImage.h"
+#include "third_party/skia/include/gpu/gl/GrGLTypes.h"
+
+namespace mojo {
+namespace skia {
+
+static void ReleaseThunk(void* data) {
+  auto release_callback = static_cast<base::Closure*>(data);
+  release_callback->Run();
+  delete release_callback;
+}
+
+::skia::RefPtr<SkImage> CreateImageFromTexture(
+    const GaneshContext::Scope& scope,
+    uint32_t texture_id,
+    uint32_t width,
+    uint32_t height,
+    const base::Closure& release_callback) {
+  DCHECK(texture_id);
+  DCHECK(width);
+  DCHECK(height);
+
+  // TODO(jeffbrown): Give the caller more control over these parameters
+  // as required.
+  GrGLTextureInfo info;
+  info.fTarget = GL_TEXTURE_2D;
+  info.fID = texture_id;
+
+  GrBackendTextureDesc desc;
+  desc.fFlags = kRenderTarget_GrBackendTextureFlag;
+  desc.fWidth = width;
+  desc.fHeight = height;
+  desc.fConfig = kSkia8888_GrPixelConfig;
+  desc.fOrigin = kTopLeft_GrSurfaceOrigin;
+  desc.fTextureHandle = reinterpret_cast<GrBackendObject>(&info);
+  return ::skia::AdoptRef(SkImage::NewFromTexture(
+      scope.gr_context(), desc, kPremul_SkAlphaType, &ReleaseThunk,
+      new base::Closure(release_callback)));
+}
+
+}  // namespace skia
+}  // namespace mojo