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comparison: gfx/2d/BorrowedContext.h
gfx/2d/BorrowedContext.h
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| 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/. */ | |
| 5 | |
| 6 #ifndef _MOZILLA_GFX_BORROWED_CONTEXT_H | |
| 7 #define _MOZILLA_GFX_BORROWED_CONTEXT_H | |
| 8 | |
| 9 #include "2D.h" | |
| 10 | |
| 11 struct _cairo; | |
| 12 typedef struct _cairo cairo_t; | |
| 13 | |
| 14 namespace mozilla { | |
| 15 | |
| 16 namespace gfx { | |
| 17 | |
| 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 { } | |
| 31 | |
| 32 BorrowedCairoContext(DrawTarget *aDT) | |
| 33 : mDT(aDT) | |
| 34 { | |
| 35 mCairo = BorrowCairoContextFromDrawTarget(aDT); | |
| 36 } | |
| 37 | |
| 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 } | |
| 47 | |
| 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 } | |
| 60 | |
| 61 ~BorrowedCairoContext() { | |
| 62 MOZ_ASSERT(!mCairo); | |
| 63 } | |
| 64 | |
| 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 }; | |
| 71 | |
| 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 { } | |
| 86 | |
| 87 BorrowedCGContext(DrawTarget *aDT) | |
| 88 : mDT(aDT) | |
| 89 { | |
| 90 cg = BorrowCGContextFromDrawTarget(aDT); | |
| 91 } | |
| 92 | |
| 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 } | |
| 103 | |
| 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 } | |
| 116 | |
| 117 ~BorrowedCGContext() { | |
| 118 MOZ_ASSERT(!cg); | |
| 119 } | |
| 120 | |
| 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 | |
| 128 | |
| 129 } | |
| 130 } | |
| 131 | |
| 132 #endif // _MOZILLA_GFX_BORROWED_CONTEXT_H |
