michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * vim: sw=2 ts=8 et :
michael@0:  */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef mozilla_layers_Composer2D_h
michael@0: #define mozilla_layers_Composer2D_h
michael@0: 
michael@0: #include "gfxTypes.h"
michael@0: #include "nsISupportsImpl.h"
michael@0: 
michael@0: /**
michael@0:  * Many platforms have dedicated hardware for simple composition.
michael@0:  * This hardware is usually faster or more power efficient than the
michael@0:  * GPU.  However, in exchange for this better performance, generality
michael@0:  * has to be sacrificed: no 3d transforms, no intermediate surfaces,
michael@0:  * no special shader effects, loss of other goodies depending on the
michael@0:  * platform.
michael@0:  *
michael@0:  * Composer2D is a very simple interface to this class of hardware
michael@0:  * that allows an implementation to "try rendering" with the fast
michael@0:  * path.  If the given layer tree requires more generality than the
michael@0:  * hardware provides, the implementation should bail and have the
michael@0:  * layer manager fall back on full GPU composition.
michael@0:  */
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: namespace gfx {
michael@0: struct Matrix;
michael@0: }
michael@0: 
michael@0: namespace layers {
michael@0: 
michael@0: class Layer;
michael@0: 
michael@0: class Composer2D {
michael@0:   NS_INLINE_DECL_REFCOUNTING(Composer2D)
michael@0: 
michael@0: protected:
michael@0:   // Protected destructor, to discourage deletion outside of Release():
michael@0:   virtual ~Composer2D() {}
michael@0: 
michael@0: public:
michael@0:   /**
michael@0:    * Return true if |aRoot| met the implementation's criteria for fast
michael@0:    * composition and the render was successful.  Return false to fall
michael@0:    * back on the GPU.
michael@0:    *
michael@0:    * |aWorldTransform| must be applied to |aRoot|'s subtree when
michael@0:    * rendering to the framebuffer.  This is a global transform on the
michael@0:    * entire scene, defined in GL space.  If the Composer2D
michael@0:    * implementation is unable to honor the transform, it should return
michael@0:    * false.
michael@0:    *
michael@0:    * Currently, when TryRender() returns true, the entire framebuffer
michael@0:    * must have been rendered.
michael@0:    */
michael@0:   virtual bool TryRender(Layer* aRoot, const gfx::Matrix& aWorldTransform,
michael@0:                          bool aGeometryChanged) = 0;
michael@0: };
michael@0: 
michael@0: } // namespace layers
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif // mozilla_layers_Composer2D_h