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      1 /*
      2  * Copyright 2016 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrReducedClip_DEFINED
      9 #define GrReducedClip_DEFINED
     10 
     11 #include "GrWindowRectangles.h"
     12 #include "SkClipStack.h"
     13 #include "SkTLList.h"
     14 
     15 class GrContext;
     16 class GrRenderTargetContext;
     17 
     18 /**
     19  * This class takes a clip stack and produces a reduced set of elements that are equivalent to
     20  * applying that full stack within a specified query rectangle.
     21  */
     22 class SK_API GrReducedClip {
     23 public:
     24     GrReducedClip(const SkClipStack&, const SkRect& queryBounds, int maxWindowRectangles = 0);
     25 
     26     /**
     27      * If hasIBounds() is true, this is the bounding box within which the clip elements are valid.
     28      * The caller must not modify any pixels outside this box. Undefined if hasIBounds() is false.
     29      */
     30     const SkIRect& ibounds() const { SkASSERT(fHasIBounds); return fIBounds; }
     31     int left() const { return this->ibounds().left(); }
     32     int top() const { return this->ibounds().top(); }
     33     int width() const { return this->ibounds().width(); }
     34     int height() const { return this->ibounds().height(); }
     35 
     36     /**
     37      * Indicates whether ibounds() are defined. They will always be defined if the elements() are
     38      * nonempty.
     39      */
     40     bool hasIBounds() const { return fHasIBounds; }
     41 
     42     /**
     43      * If nonempty, this is a set of "exclusive" windows within which the clip elements are NOT
     44      * valid. The caller must not modify any pixels inside these windows.
     45      */
     46     const GrWindowRectangles& windowRectangles() const { return fWindowRects; }
     47 
     48     typedef SkTLList<SkClipStack::Element, 16> ElementList;
     49 
     50     /**
     51      * Populated with a minimal list of elements required to fully implement the clip.
     52      */
     53     const ElementList& elements() const { return fElements; }
     54 
     55     /**
     56      * If elements() are nonempty, uniquely identifies the list of elements within ibounds().
     57      * Otherwise undefined.
     58      */
     59     int32_t elementsGenID() const { SkASSERT(!fElements.isEmpty()); return fElementsGenID; }
     60 
     61     /**
     62      * Indicates whether antialiasing is required to process any of the clip elements.
     63      */
     64     bool requiresAA() const { return fRequiresAA; }
     65 
     66     enum class InitialState : bool {
     67         kAllIn,
     68         kAllOut
     69     };
     70 
     71     InitialState initialState() const { return fInitialState; }
     72 
     73     bool drawAlphaClipMask(GrRenderTargetContext*) const;
     74     bool drawStencilClipMask(GrContext*, GrRenderTargetContext*) const;
     75 
     76 private:
     77     void walkStack(const SkClipStack&, const SkRect& queryBounds, int maxWindowRectangles);
     78     void addInteriorWindowRectangles(int maxWindowRectangles);
     79     void addWindowRectangle(const SkRect& elementInteriorRect, bool elementIsAA);
     80     bool intersectIBounds(const SkIRect&);
     81 
     82     SkIRect              fIBounds;
     83     bool                 fHasIBounds;
     84     GrWindowRectangles   fWindowRects;
     85     ElementList          fElements;
     86     int32_t              fElementsGenID;
     87     bool                 fRequiresAA;
     88     InitialState         fInitialState;
     89 };
     90 
     91 #endif
     92