layout/svg/base/src/nsSVGMaskFrame.h

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  15  * The Original Code is the Mozilla SVG project.
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  17  * The Initial Developer of the Original Code is IBM Corporation.
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  36
  37 #ifndef __NS_SVGMASKFRAME_H__
  38 #define __NS_SVGMASKFRAME_H__
  39
  40 #include "nsSVGContainerFrame.h"
  41 #include "gfxPattern.h"
  42
  43 class gfxContext;
  44
  45 typedef nsSVGContainerFrame nsSVGMaskFrameBase;
  46
  47 class nsSVGMaskFrame : public nsSVGMaskFrameBase
  48 {
  49   friend nsIFrame*
  50   NS_NewSVGMaskFrame(nsIPresShell* aPresShell, nsIContent* aContent, nsStyleContext* aContext);
  51 protected:
  52   nsSVGMaskFrame(nsStyleContext* aContext) :
  53     nsSVGMaskFrameBase(aContext),
  54     mMaskParentMatrix(nsnull),
  55     mInUse(PR_FALSE) {}
  56
  57 public:
  58   // nsSVGMaskFrame method:
  59   already_AddRefed<gfxPattern> ComputeMaskAlpha(nsSVGRenderState *aContext,
  60                                                 nsISVGChildFrame* aParent,
  61                                                 nsIDOMSVGMatrix* aMatrix,
  62                                                 float aOpacity = 1.0f);
  63
  64   /**
  65    * Get the "type" of the frame
  66    *
  67    * @see nsGkAtoms::svgMaskFrame
  68    */
  69   virtual nsIAtom* GetType() const;
  70
  71 #ifdef DEBUG
  72   NS_IMETHOD GetFrameName(nsAString& aResult) const
  73   {
  74     return MakeFrameName(NS_LITERAL_STRING("SVGMask"), aResult);
  75   }
  76 #endif
  77
  78 private:
  79   // A helper class to allow us to paint masks safely. The helper
  80   // automatically sets and clears the mInUse flag on the mask frame
  81   // (to prevent nasty reference loops). It's easy to mess this up
  82   // and break things, so this helper makes the code far more robust.
  83   class AutoMaskReferencer
  84   {
  85   public:
  86     AutoMaskReferencer(nsSVGMaskFrame *aFrame)
  87        : mFrame(aFrame) {
  88       NS_ASSERTION(mFrame->mInUse == PR_FALSE, "reference loop!");
  89       mFrame->mInUse = PR_TRUE;
  90     }
  91     ~AutoMaskReferencer() {
  92       mFrame->mInUse = PR_FALSE;
  93     }
  94   private:
  95     nsSVGMaskFrame *mFrame;
  96   };
  97
  98   nsISVGChildFrame *mMaskParent;
  99   nsCOMPtr<nsIDOMSVGMatrix> mMaskParentMatrix;
 100   // recursion prevention flag
 101   PRPackedBool mInUse;
 102
 103   // nsSVGContainerFrame methods:
 104   virtual already_AddRefed<nsIDOMSVGMatrix> GetCanvasTM();
 105 };
 106
 107 nsIContent *
 108 NS_GetSVGMaskElement(nsIURI *aURI, nsIContent *aContent);
 109
 110 #endif