gfx/thebes/gfxCachedTempSurface.h@97036ab72558
gfx/thebes/gfxCachedTempSurface.h
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
2 * This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 #ifndef GFX_CACHED_TEMP_SURFACE_H
7 #define GFX_CACHED_TEMP_SURFACE_H
9 #include "gfxASurface.h"
10 #include "nsExpirationTracker.h"
11 #include "nsSize.h"
13 class gfxContext;
15 /**
16 * This class can be used to cache double-buffering back surfaces.
17 *
18 * Large resource allocations may have an overhead that can be avoided by
19 * caching. Caching also alows the system to use history in deciding whether
20 * to manage the surfaces in video or system memory.
21 *
22 * However, because we don't want to set aside megabytes of unused resources
23 * unncessarily, these surfaces are released on a timer.
24 */
26 class gfxCachedTempSurface {
27 public:
28 /**
29 * Returns a context for a surface that can be efficiently copied to
30 * |aSimilarTo|.
31 *
32 * When |aContentType| has an alpha component, the surface will be cleared.
33 * For opaque surfaces, the initial surface contents are undefined.
34 * When |aContentType| differs in different invocations this is handled
35 * appropriately, creating a new surface if necessary.
36 *
37 * Because the cached surface may have been created during a previous
38 * invocation, this will not be efficient if the new |aSimilarTo| has a
39 * different format, size, or gfxSurfaceType.
40 */
41 already_AddRefed<gfxContext> Get(gfxContentType aContentType,
42 const gfxRect& aRect,
43 gfxASurface* aSimilarTo);
45 void Expire() { mSurface = nullptr; }
46 nsExpirationState* GetExpirationState() { return &mExpirationState; }
47 ~gfxCachedTempSurface();
49 bool IsSurface(gfxASurface* aSurface) { return mSurface == aSurface; }
51 private:
52 nsRefPtr<gfxASurface> mSurface;
53 gfxIntSize mSize;
54 nsExpirationState mExpirationState;
55 gfxSurfaceType mType;
56 };
58 #endif /* GFX_CACHED_TEMP_SURFACE_H */
