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 "GrFragmentProcessor.h"
12 #include "GrWindowRectangles.h"
13 #include "SkClipStack.h"
14 #include "SkTLList.h"
15 
16 class GrCoverageCountingPathRenderer;
17 class GrRecordingContext;
18 class GrRenderTargetContext;
19 
20 /**
21  * This class takes a clip stack and produces a reduced set of elements that are equivalent to
22  * applying that full stack within a specified query rectangle.
23  */
24 class SK_API GrReducedClip {
25 public:
26     using Element = SkClipStack::Element;
27     using ElementList = SkTLList<SkClipStack::Element, 16>;
28 
29     GrReducedClip(const SkClipStack&, const SkRect& queryBounds, const GrCaps* caps,
30                   int maxWindowRectangles = 0, int maxAnalyticFPs = 0, int maxCCPRClipPaths = 0);
31 
32     enum class InitialState : bool {
33         kAllIn,
34         kAllOut
35     };
36 
initialState()37     InitialState initialState() const { return fInitialState; }
38 
39     /**
40      * If hasScissor() is true, the clip mask is not valid outside this rect and the caller must
41      * enforce this scissor during draw.
42      */
scissor()43     const SkIRect& scissor() const { SkASSERT(fHasScissor); return fScissor; }
left()44     int left() const { return this->scissor().left(); }
top()45     int top() const { return this->scissor().top(); }
width()46     int width() const { return this->scissor().width(); }
height()47     int height() const { return this->scissor().height(); }
48 
49     /**
50      * Indicates whether scissor() is defined. It will always be defined if the maskElements() are
51      * nonempty.
52      */
hasScissor()53     bool hasScissor() const { return fHasScissor; }
54 
55     /**
56      * If nonempty, the clip mask is not valid inside these windows and the caller must clip them
57      * out using the window rectangles GPU extension.
58      */
windowRectangles()59     const GrWindowRectangles& windowRectangles() const { return fWindowRects; }
60 
61     /**
62      * An ordered list of clip elements that could not be skipped or implemented by other means. If
63      * nonempty, the caller must create an alpha and/or stencil mask for these elements and apply it
64      * during draw.
65      */
maskElements()66     const ElementList& maskElements() const { return fMaskElements; }
67 
68     /**
69      * If maskElements() are nonempty, uniquely identifies the region of the clip mask that falls
70      * inside of scissor().
71      *
72      * NOTE: since clip elements might fall outside the query bounds, different regions of the same
73      * clip stack might have more or less restrictive IDs.
74      *
75      * FIXME: this prevents us from reusing a sub-rect of a perfectly good mask when that rect has
76      * been assigned a less restrictive ID.
77      */
maskGenID()78     uint32_t maskGenID() const { SkASSERT(!fMaskElements.isEmpty()); return fMaskGenID; }
79 
80     /**
81      * Indicates whether antialiasing is required to process any of the mask elements.
82      */
maskRequiresAA()83     bool maskRequiresAA() const { SkASSERT(!fMaskElements.isEmpty()); return fMaskRequiresAA; }
84 
85     bool drawAlphaClipMask(GrRenderTargetContext*) const;
86     bool drawStencilClipMask(GrRecordingContext*, GrRenderTargetContext*) const;
87 
numAnalyticFPs()88     int numAnalyticFPs() const { return fAnalyticFPs.count() + fCCPRClipPaths.count(); }
89 
90     /**
91      * Called once the client knows the ID of the opList that the clip FPs will operate in. This
92      * method finishes any outstanding work that was waiting for the opList ID, then detaches and
93      * returns this class's list of FPs that complete the clip.
94      *
95      * NOTE: this must be called AFTER producing the clip mask (if any) because draw calls on
96      * the render target context, surface allocations, and even switching render targets (pre MDB)
97      * may cause flushes or otherwise change which opList the actual draw is going into.
98      */
99     std::unique_ptr<GrFragmentProcessor> finishAndDetachAnalyticFPs(GrCoverageCountingPathRenderer*,
100                                                                     uint32_t opListID, int rtWidth,
101                                                                     int rtHeight);
102 
103 private:
104     void walkStack(const SkClipStack&, const SkRect& queryBounds);
105 
106     enum class ClipResult {
107         kNotClipped,
108         kClipped,
109         kMadeEmpty
110     };
111 
112     // Intersects the clip with the element's interior, regardless of inverse fill type.
113     // NOTE: do not call for elements followed by ops that can grow the clip.
114     ClipResult clipInsideElement(const Element*);
115 
116     // Intersects the clip with the element's exterior, regardless of inverse fill type.
117     // NOTE: do not call for elements followed by ops that can grow the clip.
118     ClipResult clipOutsideElement(const Element*);
119 
120     void addWindowRectangle(const SkRect& elementInteriorRect, bool elementIsAA);
121 
122     enum class Invert : bool {
123         kNo = false,
124         kYes = true
125     };
126 
127     static GrClipEdgeType GetClipEdgeType(Invert, GrAA);
128     ClipResult addAnalyticFP(const SkRect& deviceSpaceRect, Invert, GrAA);
129     ClipResult addAnalyticFP(const SkRRect& deviceSpaceRRect, Invert, GrAA);
130     ClipResult addAnalyticFP(const SkPath& deviceSpacePath, Invert, GrAA);
131 
132     void makeEmpty();
133 
134     const GrCaps* fCaps;
135     const int fMaxWindowRectangles;
136     const int fMaxAnalyticFPs;
137     const int fMaxCCPRClipPaths;
138 
139     InitialState fInitialState;
140     SkIRect fScissor;
141     bool fHasScissor;
142     SkRect fAAClipRect;
143     uint32_t fAAClipRectGenID; // GenID the mask will have if includes the AA clip rect.
144     GrWindowRectangles fWindowRects;
145     ElementList fMaskElements;
146     uint32_t fMaskGenID;
147     bool fMaskRequiresAA;
148     SkSTArray<4, std::unique_ptr<GrFragmentProcessor>> fAnalyticFPs;
149     SkSTArray<4, SkPath> fCCPRClipPaths; // Will convert to FPs once we have an opList ID for CCPR.
150 };
151 
152 #endif
153