gfx/2d/BorrowedContext.h@97036ab72558
gfx/2d/BorrowedContext.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 _MOZILLA_GFX_BORROWED_CONTEXT_H
7 #define _MOZILLA_GFX_BORROWED_CONTEXT_H
9 #include "2D.h"
11 struct _cairo;
12 typedef struct _cairo cairo_t;
14 namespace mozilla {
16 namespace gfx {
18 /* This is a helper class that let's you borrow a cairo_t from a
19 * DrawTargetCairo. This is used for drawing themed widgets.
20 *
21 * Callers should check the cr member after constructing the object
22 * to see if it succeeded. The DrawTarget should not be used while
23 * the context is borrowed. */
24 class BorrowedCairoContext
25 {
26 public:
27 BorrowedCairoContext()
28 : mCairo(nullptr)
29 , mDT(nullptr)
30 { }
32 BorrowedCairoContext(DrawTarget *aDT)
33 : mDT(aDT)
34 {
35 mCairo = BorrowCairoContextFromDrawTarget(aDT);
36 }
38 // We can optionally Init after construction in
39 // case we don't know what the DT will be at construction
40 // time.
41 cairo_t *Init(DrawTarget *aDT)
42 {
43 MOZ_ASSERT(!mDT, "Can't initialize twice!");
44 mDT = aDT;
45 return mCairo = BorrowCairoContextFromDrawTarget(aDT);
46 }
48 // The caller needs to call Finish if cr is non-null when
49 // they are done with the context. This is currently explicit
50 // instead of happening implicitly in the destructor to make
51 // what's happening in the caller more clear. It also
52 // let's you resume using the DrawTarget in the same scope.
53 void Finish()
54 {
55 if (mCairo) {
56 ReturnCairoContextToDrawTarget(mDT, mCairo);
57 mCairo = nullptr;
58 }
59 }
61 ~BorrowedCairoContext() {
62 MOZ_ASSERT(!mCairo);
63 }
65 cairo_t *mCairo;
66 private:
67 static cairo_t* BorrowCairoContextFromDrawTarget(DrawTarget *aDT);
68 static void ReturnCairoContextToDrawTarget(DrawTarget *aDT, cairo_t *aCairo);
69 DrawTarget *mDT;
70 };
72 #ifdef XP_MACOSX
73 /* This is a helper class that let's you borrow a CGContextRef from a
74 * DrawTargetCG. This is used for drawing themed widgets.
75 *
76 * Callers should check the cg member after constructing the object
77 * to see if it succeeded. The DrawTarget should not be used while
78 * the context is borrowed. */
79 class BorrowedCGContext
80 {
81 public:
82 BorrowedCGContext()
83 : cg(nullptr)
84 , mDT(nullptr)
85 { }
87 BorrowedCGContext(DrawTarget *aDT)
88 : mDT(aDT)
89 {
90 cg = BorrowCGContextFromDrawTarget(aDT);
91 }
93 // We can optionally Init after construction in
94 // case we don't know what the DT will be at construction
95 // time.
96 CGContextRef Init(DrawTarget *aDT)
97 {
98 MOZ_ASSERT(!mDT, "Can't initialize twice!");
99 mDT = aDT;
100 cg = BorrowCGContextFromDrawTarget(aDT);
101 return cg;
102 }
104 // The caller needs to call Finish if cg is non-null when
105 // they are done with the context. This is currently explicit
106 // instead of happening implicitly in the destructor to make
107 // what's happening in the caller more clear. It also
108 // let's you resume using the DrawTarget in the same scope.
109 void Finish()
110 {
111 if (cg) {
112 ReturnCGContextToDrawTarget(mDT, cg);
113 cg = nullptr;
114 }
115 }
117 ~BorrowedCGContext() {
118 MOZ_ASSERT(!cg);
119 }
121 CGContextRef cg;
122 private:
123 static CGContextRef BorrowCGContextFromDrawTarget(DrawTarget *aDT);
124 static void ReturnCGContextToDrawTarget(DrawTarget *aDT, CGContextRef cg);
125 DrawTarget *mDT;
126 };
127 #endif
129 }
130 }
132 #endif // _MOZILLA_GFX_BORROWED_CONTEXT_H
