michael@0: /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef _MOZILLA_GFX_BORROWED_CONTEXT_H
michael@0: #define _MOZILLA_GFX_BORROWED_CONTEXT_H
michael@0: 
michael@0: #include "2D.h"
michael@0: 
michael@0: struct _cairo;
michael@0: typedef struct _cairo cairo_t;
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: namespace gfx {
michael@0: 
michael@0: /* This is a helper class that let's you borrow a cairo_t from a
michael@0:  * DrawTargetCairo. This is used for drawing themed widgets.
michael@0:  *
michael@0:  * Callers should check the cr member after constructing the object
michael@0:  * to see if it succeeded. The DrawTarget should not be used while
michael@0:  * the context is borrowed. */
michael@0: class BorrowedCairoContext
michael@0: {
michael@0: public:
michael@0:   BorrowedCairoContext()
michael@0:     : mCairo(nullptr)
michael@0:     , mDT(nullptr)
michael@0:   { }
michael@0: 
michael@0:   BorrowedCairoContext(DrawTarget *aDT)
michael@0:     : mDT(aDT)
michael@0:   {
michael@0:     mCairo = BorrowCairoContextFromDrawTarget(aDT);
michael@0:   }
michael@0: 
michael@0:   // We can optionally Init after construction in
michael@0:   // case we don't know what the DT will be at construction
michael@0:   // time.
michael@0:   cairo_t *Init(DrawTarget *aDT)
michael@0:   {
michael@0:     MOZ_ASSERT(!mDT, "Can't initialize twice!");
michael@0:     mDT = aDT;
michael@0:     return mCairo = BorrowCairoContextFromDrawTarget(aDT);
michael@0:   }
michael@0: 
michael@0:   // The caller needs to call Finish if cr is non-null when
michael@0:   // they are done with the context. This is currently explicit
michael@0:   // instead of happening implicitly in the destructor to make
michael@0:   // what's happening in the caller more clear. It also
michael@0:   // let's you resume using the DrawTarget in the same scope.
michael@0:   void Finish()
michael@0:   {
michael@0:     if (mCairo) {
michael@0:       ReturnCairoContextToDrawTarget(mDT, mCairo);
michael@0:       mCairo = nullptr;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   ~BorrowedCairoContext() {
michael@0:     MOZ_ASSERT(!mCairo);
michael@0:   }
michael@0: 
michael@0:   cairo_t *mCairo;
michael@0: private:
michael@0:   static cairo_t* BorrowCairoContextFromDrawTarget(DrawTarget *aDT);
michael@0:   static void ReturnCairoContextToDrawTarget(DrawTarget *aDT, cairo_t *aCairo);
michael@0:   DrawTarget *mDT;
michael@0: };
michael@0: 
michael@0: #ifdef XP_MACOSX
michael@0: /* This is a helper class that let's you borrow a CGContextRef from a
michael@0:  * DrawTargetCG. This is used for drawing themed widgets.
michael@0:  *
michael@0:  * Callers should check the cg member after constructing the object
michael@0:  * to see if it succeeded. The DrawTarget should not be used while
michael@0:  * the context is borrowed. */
michael@0: class BorrowedCGContext
michael@0: {
michael@0: public:
michael@0:   BorrowedCGContext()
michael@0:     : cg(nullptr)
michael@0:     , mDT(nullptr)
michael@0:   { }
michael@0: 
michael@0:   BorrowedCGContext(DrawTarget *aDT)
michael@0:     : mDT(aDT)
michael@0:   {
michael@0:     cg = BorrowCGContextFromDrawTarget(aDT);
michael@0:   }
michael@0: 
michael@0:   // We can optionally Init after construction in
michael@0:   // case we don't know what the DT will be at construction
michael@0:   // time.
michael@0:   CGContextRef Init(DrawTarget *aDT)
michael@0:   {
michael@0:     MOZ_ASSERT(!mDT, "Can't initialize twice!");
michael@0:     mDT = aDT;
michael@0:     cg = BorrowCGContextFromDrawTarget(aDT);
michael@0:     return cg;
michael@0:   }
michael@0: 
michael@0:   // The caller needs to call Finish if cg is non-null when
michael@0:   // they are done with the context. This is currently explicit
michael@0:   // instead of happening implicitly in the destructor to make
michael@0:   // what's happening in the caller more clear. It also
michael@0:   // let's you resume using the DrawTarget in the same scope.
michael@0:   void Finish()
michael@0:   {
michael@0:     if (cg) {
michael@0:       ReturnCGContextToDrawTarget(mDT, cg);
michael@0:       cg = nullptr;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   ~BorrowedCGContext() {
michael@0:     MOZ_ASSERT(!cg);
michael@0:   }
michael@0: 
michael@0:   CGContextRef cg;
michael@0: private:
michael@0:   static CGContextRef BorrowCGContextFromDrawTarget(DrawTarget *aDT);
michael@0:   static void ReturnCGContextToDrawTarget(DrawTarget *aDT, CGContextRef cg);
michael@0:   DrawTarget *mDT;
michael@0: };
michael@0: #endif
michael@0: 
michael@0: }
michael@0: }
michael@0: 
michael@0: #endif // _MOZILLA_GFX_BORROWED_CONTEXT_H