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1 
2 /*
3  * Copyright 2012 Google Inc.
4  *
5  * Use of this source code is governed by a BSD-style license that can be
6  * found in the LICENSE file.
7  */
8 
9 #include "SkClipStack.h"
10 #include "SkTLList.h"
11 
12 namespace GrReducedClip {
13 
14 typedef SkTLList<SkClipStack::Element> ElementList;
15 
16 enum InitialState {
17     kAllIn_InitialState,
18     kAllOut_InitialState,
19 };
20 
21 /**
22  * This function takes a clip stack and a query rectangle and it produces a reduced set of
23  * SkClipStack::Elements that are equivalent to applying the full stack to the rectangle. The clip
24  * stack generation id that represents the list of elements is returned in resultGenID. The
25  * initial state of the query rectangle before the first clip element is applied is returned via
26  * initialState. Optionally, the caller can request a tighter bounds on the clip be returned via
27  * tighterBounds. If not NULL, tighterBounds will always be contained by queryBounds after return.
28  * If tighterBounds is specified then it is assumed that the caller will implicitly clip against it.
29  * If the caller specifies non-NULL for requiresAA then it will indicate whether anti-aliasing is
30  * required to process any of the elements in the result.
31  *
32  * This may become a member function of SkClipStack when its interface is determined to be stable.
33  */
34 void ReduceClipStack(const SkClipStack& stack,
35                      const SkIRect& queryBounds,
36                      ElementList* result,
37                      int32_t* resultGenID,
38                      InitialState* initialState,
39                      SkIRect* tighterBounds = NULL,
40                      bool* requiresAA = NULL);
41 
42 } // namespace GrReducedClip
43