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 GrScissorState_DEFINED
9#define GrScissorState_DEFINED
10
11#include "include/core/SkRect.h"
12
13/**
14 * The scissor state is stored as the scissor rectangle and the backing store bounds of the render
15 * target that the scissor will apply to. If the render target is approximate fit and the padded
16 * content should not be modified, the clip should apply the render target context's logical bounds
17 * as part of the scissor (e.g. when stenciling). This puts the onus on the render target context
18 * to intentionally discard the scissor at its logical bounds when drawing into the padded content
19 * is acceptable (e.g. color-only updates).
20 */
21class GrScissorState {
22public:
23 // The disabled scissor state for a render target of the given size.
24 explicit GrScissorState(const SkISize& rtDims)
25 : fRTSize(rtDims)
26 , fRect(SkIRect::MakeSize(rtDims)) {}
27
28 void setDisabled() { fRect = SkIRect::MakeSize(fRTSize); }
29 bool set(const SkIRect& rect) {
30 this->setDisabled();
31 return this->intersect(rect);
32 }
33
34 bool SK_WARN_UNUSED_RESULT intersect(const SkIRect& rect) {
35 if (!fRect.intersect(rect)) {
36 fRect.setEmpty();
37 return false;
38 } else {
39 return true;
40 }
41 }
42
43 // If the scissor was configured for the backing store dimensions and it's acceptable to
44 // draw outside the logical dimensions of the target, this will discard the scissor test if
45 // the test wouldn't modify the logical dimensions.
46 bool relaxTest(const SkISize& logicalDimensions) {
47 SkASSERT(logicalDimensions.fWidth <= fRTSize.fWidth &&
48 logicalDimensions.fHeight <= fRTSize.fHeight);
49 if (fRect.fLeft == 0 && fRect.fTop == 0 && fRect.fRight >= logicalDimensions.fWidth &&
50 fRect.fBottom >= logicalDimensions.fHeight) {
51 this->setDisabled();
52 return true;
53 } else {
54 return false;
55 }
56 }
57
58 bool operator==(const GrScissorState& other) const {
59 return fRTSize == other.fRTSize && fRect == other.fRect;
60 }
61 bool operator!=(const GrScissorState& other) const { return !(*this == other); }
62
63 bool enabled() const {
64 SkASSERT(fRect.isEmpty() || SkIRect::MakeSize(fRTSize).contains(fRect));
65 // This is equivalent to a strict contains check on SkIRect::MakeSize(rtSize) w/o creating
66 // the render target bounding rectangle.
67 return fRect.fLeft > 0 || fRect.fTop > 0 ||
68 fRect.fRight < fRTSize.fWidth || fRect.fBottom < fRTSize.fHeight;
69 }
70
71 // Will always be equal to or contained in the rt bounds, or empty if scissor rectangles were
72 // added that did not intersect with the render target or prior scissor.
73 const SkIRect& rect() const {
74 SkASSERT(fRect.isEmpty() || SkIRect::MakeSize(fRTSize).contains(fRect));
75 return fRect;
76 }
77
78private:
79 // The scissor is considered enabled if the rectangle does not cover the render target
80 SkISize fRTSize;
81 SkIRect fRect;
82};
83
84#endif
85