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133 lines
3.4 KiB
C++
133 lines
3.4 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef _MOZILLA_GFX_BORROWED_CONTEXT_H
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#define _MOZILLA_GFX_BORROWED_CONTEXT_H
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#include "2D.h"
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struct _cairo;
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typedef struct _cairo cairo_t;
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namespace mozilla {
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namespace gfx {
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/* This is a helper class that let's you borrow a cairo_t from a
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* DrawTargetCairo. This is used for drawing themed widgets.
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*
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* Callers should check the cr member after constructing the object
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* to see if it succeeded. The DrawTarget should not be used while
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* the context is borrowed. */
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class BorrowedCairoContext
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{
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public:
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BorrowedCairoContext()
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: mCairo(nullptr)
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, mDT(nullptr)
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{ }
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BorrowedCairoContext(DrawTarget *aDT)
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: mDT(aDT)
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{
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mCairo = BorrowCairoContextFromDrawTarget(aDT);
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}
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// We can optionally Init after construction in
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// case we don't know what the DT will be at construction
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// time.
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cairo_t *Init(DrawTarget *aDT)
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{
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MOZ_ASSERT(!mDT, "Can't initialize twice!");
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mDT = aDT;
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return mCairo = BorrowCairoContextFromDrawTarget(aDT);
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}
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// The caller needs to call Finish if cr is non-null when
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// they are done with the context. This is currently explicit
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// instead of happening implicitly in the destructor to make
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// what's happening in the caller more clear. It also
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// let's you resume using the DrawTarget in the same scope.
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void Finish()
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{
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if (mCairo) {
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ReturnCairoContextToDrawTarget(mDT, mCairo);
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mCairo = nullptr;
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}
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}
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~BorrowedCairoContext() {
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MOZ_ASSERT(!mCairo);
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}
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cairo_t *mCairo;
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private:
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static cairo_t* BorrowCairoContextFromDrawTarget(DrawTarget *aDT);
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static void ReturnCairoContextToDrawTarget(DrawTarget *aDT, cairo_t *aCairo);
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DrawTarget *mDT;
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};
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#ifdef XP_MACOSX
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/* This is a helper class that let's you borrow a CGContextRef from a
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* DrawTargetCG. This is used for drawing themed widgets.
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*
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* Callers should check the cg member after constructing the object
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* to see if it succeeded. The DrawTarget should not be used while
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* the context is borrowed. */
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class BorrowedCGContext
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{
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public:
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BorrowedCGContext()
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: cg(nullptr)
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, mDT(nullptr)
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{ }
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BorrowedCGContext(DrawTarget *aDT)
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: mDT(aDT)
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{
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cg = BorrowCGContextFromDrawTarget(aDT);
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}
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// We can optionally Init after construction in
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// case we don't know what the DT will be at construction
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// time.
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CGContextRef Init(DrawTarget *aDT)
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{
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MOZ_ASSERT(!mDT, "Can't initialize twice!");
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mDT = aDT;
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cg = BorrowCGContextFromDrawTarget(aDT);
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return cg;
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}
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// The caller needs to call Finish if cg is non-null when
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// they are done with the context. This is currently explicit
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// instead of happening implicitly in the destructor to make
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// what's happening in the caller more clear. It also
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// let's you resume using the DrawTarget in the same scope.
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void Finish()
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{
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if (cg) {
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ReturnCGContextToDrawTarget(mDT, cg);
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cg = nullptr;
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}
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}
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~BorrowedCGContext() {
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MOZ_ASSERT(!cg);
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}
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CGContextRef cg;
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private:
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static CGContextRef BorrowCGContextFromDrawTarget(DrawTarget *aDT);
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static void ReturnCGContextToDrawTarget(DrawTarget *aDT, CGContextRef cg);
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DrawTarget *mDT;
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};
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#endif
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}
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}
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#endif // _MOZILLA_GFX_BORROWED_CONTEXT_H
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