1 files changed, 38 insertions, 0 deletions
diff --git a/widget/WindowSurface.h b/widget/WindowSurface.h
new file mode 100644
index 0000000000..f852e83bce
--- /dev/null
+++ b/widget/WindowSurface.h
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _MOZILLA_WIDGET_WINDOW_SURFACE_H
+#define _MOZILLA_WIDGET_WINDOW_SURFACE_H
+
+#include "mozilla/gfx/2D.h"
+#include "Units.h"
+
+namespace mozilla {
+namespace widget {
+
+// A class for drawing to double-buffered windows.
+class WindowSurface {
+ public:
+  virtual ~WindowSurface() = default;
+
+  // Locks a region of the window for drawing, returning a draw target
+  // capturing the bounds of the provided region.
+  // Implementations must permit invocation from any thread.
+  virtual already_AddRefed<gfx::DrawTarget> Lock(
+      const LayoutDeviceIntRegion& aRegion) = 0;
+
+  // Swaps the provided invalid region from the back buffer to the window.
+  // Implementations must permit invocation from any thread.
+  virtual void Commit(const LayoutDeviceIntRegion& aInvalidRegion) = 0;
+
+  // Whether the window surface represents a fallback method.
+  virtual bool IsFallback() const { return false; }
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // _MOZILLA_WIDGET_WINDOW_SURFACE_H