gfx/2d/BorrowedContext.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef _MOZILLA_GFX_BORROWED_CONTEXT_H
   8 #define _MOZILLA_GFX_BORROWED_CONTEXT_H
   9
  10 #include "2D.h"
  11
  12 #ifdef MOZ_X11
  13 #  include <X11/Xlib.h>
  14 #  include "X11UndefineNone.h"
  15 #endif
  16
  17 namespace mozilla {
  18
  19 namespace gfx {
  20
  21 #ifdef MOZ_X11
  22 /* This is a helper class that let's you borrow an Xlib drawable from
  23  * a DrawTarget. This is used for drawing themed widgets.
  24  *
  25  * Callers should check the Xlib drawable after constructing the object
  26  * to see if it succeeded. The DrawTarget should not be used while
  27  * the drawable is borrowed. */
  28 class BorrowedXlibDrawable {
  29  public:
  30   BorrowedXlibDrawable()
  31       : mDT(nullptr),
  32         mDisplay(nullptr),
  33         mDrawable(X11None),
  34         mScreen(nullptr),
  35         mVisual(nullptr) {}
  36
  37   explicit BorrowedXlibDrawable(DrawTarget* aDT)
  38       : mDT(nullptr),
  39         mDisplay(nullptr),
  40         mDrawable(X11None),
  41         mScreen(nullptr),
  42         mVisual(nullptr) {
  43     Init(aDT);
  44   }
  45
  46   // We can optionally Init after construction in
  47   // case we don't know what the DT will be at construction
  48   // time.
  49   bool Init(DrawTarget* aDT);
  50
  51   // The caller needs to call Finish if drawable is non-zero when
  52   // they are done with the context. This is currently explicit
  53   // instead of happening implicitly in the destructor to make
  54   // what's happening in the caller more clear. It also
  55   // let's you resume using the DrawTarget in the same scope.
  56   void Finish();
  57
  58   ~BorrowedXlibDrawable() { MOZ_ASSERT(!mDrawable); }
  59
  60   Display* GetDisplay() const { return mDisplay; }
  61   Drawable GetDrawable() const { return mDrawable; }
  62   Screen* GetScreen() const { return mScreen; }
  63   Visual* GetVisual() const { return mVisual; }
  64   IntSize GetSize() const { return mSize; }
  65   Point GetOffset() const { return mOffset; }
  66
  67  private:
  68   DrawTarget* mDT;
  69   Display* mDisplay;
  70   Drawable mDrawable;
  71   Screen* mScreen;
  72   Visual* mVisual;
  73   IntSize mSize;
  74   Point mOffset;
  75 };
  76 #endif
  77
  78 #ifdef XP_DARWIN
  79 /* This is a helper class that let's you borrow a CGContextRef from a
  80  * DrawTargetCG. This is used for drawing themed widgets.
  81  *
  82  * Callers should check the cg member after constructing the object
  83  * to see if it succeeded. The DrawTarget should not be used while
  84  * the context is borrowed. */
  85 class BorrowedCGContext {
  86  public:
  87   BorrowedCGContext() : cg(nullptr), mDT(nullptr) {}
  88
  89   explicit BorrowedCGContext(DrawTarget* aDT) : mDT(aDT) {
  90     MOZ_ASSERT(aDT, "Caller should check for nullptr");
  91     cg = BorrowCGContextFromDrawTarget(aDT);
  92   }
  93
  94   // We can optionally Init after construction in
  95   // case we don't know what the DT will be at construction
  96   // time.
  97   CGContextRef Init(DrawTarget* aDT) {
  98     MOZ_ASSERT(aDT, "Caller should check for nullptr");
  99     MOZ_ASSERT(!mDT, "Can't initialize twice!");
 100     mDT = aDT;
 101     cg = BorrowCGContextFromDrawTarget(aDT);
 102     return cg;
 103   }
 104
 105   // The caller needs to call Finish if cg is non-null when
 106   // they are done with the context. This is currently explicit
 107   // instead of happening implicitly in the destructor to make
 108   // what's happening in the caller more clear. It also
 109   // let's you resume using the DrawTarget in the same scope.
 110   void Finish() {
 111     if (cg) {
 112       ReturnCGContextToDrawTarget(mDT, cg);
 113       cg = nullptr;
 114     }
 115   }
 116
 117   ~BorrowedCGContext() { MOZ_ASSERT(!cg); }
 118
 119   CGContextRef cg;
 120
 121  private:
 122   static CGContextRef BorrowCGContextFromDrawTarget(DrawTarget* aDT);
 123   static void ReturnCGContextToDrawTarget(DrawTarget* aDT, CGContextRef cg);
 124   DrawTarget* mDT;
 125 };
 126 #endif
 127
 128 }  // namespace gfx
 129 }  // namespace mozilla
 130
 131 #endif  // _MOZILLA_GFX_BORROWED_CONTEXT_H