gecko-dev/gfx/thebes/gfxCachedTempSurface.h

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3.5 KiB
C++

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Corporation code.
*
* The Initial Developer of the Original Code is Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Karl Tomlinson <karlt+@karlt.net>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef GFX_CACHED_TEMP_SURFACE_H
#define GFX_CACHED_TEMP_SURFACE_H
#include "gfxASurface.h"
#include "nsExpirationTracker.h"
class gfxContext;
/**
* This class can be used to cache double-buffering back surfaces.
*
* Large resource allocations may have an overhead that can be avoided by
* caching. Caching also alows the system to use history in deciding whether
* to manage the surfaces in video or system memory.
*
* However, because we don't want to set aside megabytes of unused resources
* unncessarily, these surfaces are released on a timer.
*/
class THEBES_API gfxCachedTempSurface {
public:
/**
* Returns a context for a surface that can be efficiently copied to
* |aSimilarTo|.
*
* When |aContentType| has an alpha component, the surface will be cleared.
* For opaque surfaces, the initial surface contents are undefined.
* When |aContentType| differs in different invocations this is handled
* appropriately, creating a new surface if necessary.
*
* |aSimilarTo| should be of the same gfxSurfaceType in each invocation.
* Because the cached surface may have been created during a previous
* invocation, this will not be efficient if the new |aSimilarTo| has a
* different format.
*/
already_AddRefed<gfxContext> Get(gfxASurface::gfxContentType aContentType,
const gfxIntSize& aSize,
gfxASurface* aSimilarTo);
void Expire() { mSurface = nsnull; }
nsExpirationState* GetExpirationState() { return &mExpirationState; }
~gfxCachedTempSurface();
private:
nsRefPtr<gfxASurface> mSurface;
gfxIntSize mSize;
nsExpirationState mExpirationState;
#ifdef DEBUG
gfxASurface::gfxSurfaceType mType;
#endif
};
#endif /* GFX_CACHED_TEMP_SURFACE_H */