1 files changed, 78 insertions, 0 deletions
diff --git a/gfx/gl/GLScreenBuffer.h b/gfx/gl/GLScreenBuffer.h
new file mode 100644
index 0000000000..17a4bd9c2f
--- /dev/null
+++ b/gfx/gl/GLScreenBuffer.h
@@ -0,0 +1,78 @@
+/* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 4; -*- */
+/* 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/. */
+
+/* GLScreenBuffer is the abstraction for the "default framebuffer" used
+ * by an offscreen GLContext. Since it's only for offscreen GLContext's,
+ * it's only useful for things like WebGL, and is NOT used by the
+ * compositor's GLContext. Remember that GLContext provides an abstraction
+ * so that even if you want to draw to the 'screen', even if that's not
+ * actually the screen, just draw to 0. This GLScreenBuffer class takes the
+ * logic handling out of GLContext.
+ */
+
+#ifndef SCREEN_BUFFER_H_
+#define SCREEN_BUFFER_H_
+
+#include "GLTypes.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/UniquePtr.h"
+
+#include <queue>
+#include <memory>
+
+namespace mozilla {
+namespace gl {
+
+class SharedSurface;
+class SurfaceFactory;
+class SwapChain;
+
+class SwapChainPresenter final {
+  friend class SwapChain;
+
+  SwapChain* mSwapChain;
+  std::shared_ptr<SharedSurface> mBackBuffer;
+
+ public:
+  explicit SwapChainPresenter(SwapChain& swapChain);
+  ~SwapChainPresenter();
+
+  const auto& BackBuffer() const { return mBackBuffer; }
+
+  std::shared_ptr<SharedSurface> SwapBackBuffer(std::shared_ptr<SharedSurface>);
+  GLuint Fb() const;
+};
+
+// -
+
+class SwapChain final {
+  friend class SwapChainPresenter;
+
+ public:
+  UniquePtr<SurfaceFactory> mFactory;
+
+ private:
+  std::queue<std::shared_ptr<SharedSurface>> mPool;
+  std::shared_ptr<SharedSurface> mFrontBuffer;
+
+ public:
+  std::shared_ptr<SharedSurface>
+      mPrevFrontBuffer;  // Hold this ref while it's in-flight.
+ private:
+  SwapChainPresenter* mPresenter = nullptr;
+
+ public:
+  SwapChain();
+  virtual ~SwapChain();
+
+  void ClearPool();
+  const auto& FrontBuffer() const { return mFrontBuffer; }
+  UniquePtr<SwapChainPresenter> Acquire(const gfx::IntSize&);
+};
+
+}  // namespace gl
+}  // namespace mozilla
+
+#endif  // SCREEN_BUFFER_H_