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 "src/core/SkClipStack.h"
12#include "src/core/SkTLList.h"
13#include "src/gpu/GrFragmentProcessor.h"
14#include "src/gpu/GrWindowRectangles.h"
15
16class GrCoverageCountingPathRenderer;
17class GrRecordingContext;
18class 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 */
24class GrReducedClip {
25public:
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 maxAnalyticElements = 0,
31 int maxCCPRClipPaths = 0);
32
33 enum class InitialState : bool {
34 kAllIn,
35 kAllOut
36 };
37
38 InitialState initialState() const { return fInitialState; }
39
40 /**
41 * If hasScissor() is true, the clip mask is not valid outside this rect and the caller must
42 * enforce this scissor during draw.
43 */
44 const SkIRect& scissor() const { SkASSERT(fHasScissor); return fScissor; }
45 int left() const { return this->scissor().left(); }
46 int top() const { return this->scissor().top(); }
47 int width() const { return this->scissor().width(); }
48 int height() const { return this->scissor().height(); }
49
50 /**
51 * Indicates whether scissor() is defined. It will always be defined if the maskElements() are
52 * nonempty.
53 */
54 bool hasScissor() const { return fHasScissor; }
55
56 /**
57 * Indicates if there is a clip shader, representing the merge of all shader elements of the
58 * original stack.
59 */
60 bool hasShader() const { return SkToBool(fShader); }
61 sk_sp<SkShader> shader() const { SkASSERT(fShader); return fShader; }
62
63 /**
64 * If nonempty, the clip mask is not valid inside these windows and the caller must clip them
65 * out using the window rectangles GPU extension.
66 */
67 const GrWindowRectangles& windowRectangles() const { return fWindowRects; }
68
69 /**
70 * An ordered list of clip elements that could not be skipped or implemented by other means. If
71 * nonempty, the caller must create an alpha and/or stencil mask for these elements and apply it
72 * during draw.
73 */
74 const ElementList& maskElements() const { return fMaskElements; }
75
76 /**
77 * If maskElements() are nonempty, uniquely identifies the region of the clip mask that falls
78 * inside of scissor().
79 *
80 * NOTE: since clip elements might fall outside the query bounds, different regions of the same
81 * clip stack might have more or less restrictive IDs.
82 *
83 * FIXME: this prevents us from reusing a sub-rect of a perfectly good mask when that rect has
84 * been assigned a less restrictive ID.
85 */
86 uint32_t maskGenID() const { SkASSERT(!fMaskElements.isEmpty()); return fMaskGenID; }
87
88 /**
89 * Indicates whether antialiasing is required to process any of the mask elements.
90 */
91 bool maskRequiresAA() const { SkASSERT(!fMaskElements.isEmpty()); return fMaskRequiresAA; }
92
93 bool drawAlphaClipMask(GrRenderTargetContext*) const;
94 bool drawStencilClipMask(GrRecordingContext*, GrRenderTargetContext*) const;
95
96 int numAnalyticElements() const;
97
98 /**
99 * Called once the client knows the ID of the opsTask that the clip FPs will operate in. This
100 * method finishes any outstanding work that was waiting for the opsTask ID, then detaches and
101 * returns this class's list of FPs that complete the clip.
102 *
103 * NOTE: this must be called AFTER producing the clip mask (if any) because draw calls on
104 * the render target context, surface allocations, and even switching render targets (pre MDB)
105 * may cause flushes or otherwise change which opsTask the actual draw is going into.
106 */
107 std::unique_ptr<GrFragmentProcessor> finishAndDetachAnalyticElements(
108 GrRecordingContext*, const SkMatrixProvider& matrixProvider,
109 GrCoverageCountingPathRenderer*, uint32_t opsTaskID);
110
111private:
112 void walkStack(const SkClipStack&, const SkRect& queryBounds);
113
114 enum class ClipResult {
115 kNotClipped,
116 kClipped,
117 kMadeEmpty
118 };
119
120 // Intersects the clip with the element's interior, regardless of inverse fill type.
121 // NOTE: do not call for elements followed by ops that can grow the clip.
122 ClipResult clipInsideElement(const Element*);
123
124 // Intersects the clip with the element's exterior, regardless of inverse fill type.
125 // NOTE: do not call for elements followed by ops that can grow the clip.
126 ClipResult clipOutsideElement(const Element*);
127
128 void addWindowRectangle(const SkRect& elementInteriorRect, bool elementIsAA);
129
130 enum class Invert : bool {
131 kNo = false,
132 kYes = true
133 };
134
135 static GrClipEdgeType GetClipEdgeType(Invert, GrAA);
136 ClipResult addAnalyticRect(const SkRect& deviceSpaceRect, Invert, GrAA);
137 ClipResult addAnalyticRRect(const SkRRect& deviceSpaceRRect, Invert, GrAA);
138 ClipResult addAnalyticPath(const SkPath& deviceSpacePath, Invert, GrAA);
139
140 void makeEmpty();
141
142 const GrCaps* fCaps;
143 const int fMaxWindowRectangles;
144 const int fMaxAnalyticElements;
145 const int fMaxCCPRClipPaths;
146
147 InitialState fInitialState;
148 SkIRect fScissor;
149 bool fHasScissor = false;
150 SkRect fAAClipRect;
151 uint32_t fAAClipRectGenID = SK_InvalidGenID; // the GenID that the mask will have if the AA
152 // clip-rect is included
153 GrWindowRectangles fWindowRects;
154 ElementList fMaskElements;
155 uint32_t fMaskGenID = SK_InvalidGenID;
156 bool fMaskRequiresAA = false;
157 std::unique_ptr<GrFragmentProcessor> fAnalyticFP;
158 int fNumAnalyticElements = 0;
159 SkSTArray<4, SkPath> fCCPRClipPaths; // Converted to FPs once we have an opsTask ID for CCPR.
160 // Will be the combination of all kShader elements or null if there's no clip shader.
161 // Does not count against the analytic FP limit.
162 sk_sp<SkShader> fShader;
163};
164
165#endif
166