Add helpers for creating UI components.

mojo/ui/ganesh_renderer.h

+// Copyright 2015 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.
+
+#ifndef MOJO_UI_GANESH_RENDERER_H_
+#define MOJO_UI_GANESH_RENDERER_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "mojo/services/gfx/composition/interfaces/resources.mojom.h"
+#include "mojo/ui/gl_renderer.h"
+
+class SkCanvas;
+class SkSurface;
+
+namespace mojo {
+namespace skia {
+class GaneshContext;
+}  // namespace skia
+
+namespace ui {
+
+// Provides support for rendering Skia commands into surfaces backed by
+// a pool of textures and producing scene resources for them.
+class GaneshRenderer {
+ public:
+  // Called with an active GaneshContext and a Skia surface or canvas
+  // to draw into the framebuffer.
+  using DrawSurfaceCallback = base::Callback<void(SkSurface* surface)>;
+  using DrawCanvasCallback = base::Callback<void(SkCanvas* canvas)>;
+
+  // Creates a Ganesh backed renderer.
+  // Does not take ownership of |ganesh_context|; it must outlive the renderer.
+  explicit GaneshRenderer(mojo::skia::GaneshContext* ganesh_context);
+  ~GaneshRenderer();
+
+  // Gets the Ganesh context.
+  mojo::skia::GaneshContext* ganesh_context() { return ganesh_context_; }
+
+  // Allocates a GL texture, binds it to a Ganesh surface or canvas,
+  // invokes the provided function, then returns the resulting resource.
+  mojo::gfx::composition::ResourcePtr DrawSurface(
+      const mojo::Size& size,
+      const DrawSurfaceCallback& callback);
+  mojo::gfx::composition::ResourcePtr DrawCanvas(
+      const mojo::Size& size,
+      const DrawCanvasCallback& callback);
+
+ private:
+  mojo::skia::GaneshContext* ganesh_context_;
+  mojo::ui::GLRenderer gl_renderer_;
+
+  DISALLOW_COPY_AND_ASSIGN(GaneshRenderer);
+};
+
+}  // namespace ui
+}  // namespace mojo
+
+#endif  // MOJO_UI_GANESH_RENDERER_H_