1
2 /*
3 * Copyright 2013 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 #include "SkCanvasStack.h"
9
SkCanvasStack(int width,int height)10 SkCanvasStack::SkCanvasStack(int width, int height)
11 : INHERITED(width, height) {}
12
~SkCanvasStack()13 SkCanvasStack::~SkCanvasStack() {
14 this->removeAll();
15 }
16
pushCanvas(SkCanvas * canvas,const SkIPoint & origin)17 void SkCanvasStack::pushCanvas(SkCanvas* canvas, const SkIPoint& origin) {
18 if (canvas) {
19 // compute the bounds of this canvas
20 const SkIRect canvasBounds = SkIRect::MakeSize(canvas->getDeviceSize());
21
22 // push the canvas onto the stack
23 this->INHERITED::addCanvas(canvas);
24
25 // push the canvas data onto the stack
26 CanvasData* data = &fCanvasData.push_back();
27 data->origin = origin;
28 data->requiredClip.setRect(canvasBounds);
29
30 // subtract this region from the canvas objects already on the stack.
31 // This ensures they do not draw into the space occupied by the layers
32 // above them.
33 for (int i = fList.count() - 1; i > 0; --i) {
34 SkIRect localBounds = canvasBounds;
35 localBounds.offset(origin - fCanvasData[i-1].origin);
36
37 fCanvasData[i-1].requiredClip.op(localBounds, SkRegion::kDifference_Op);
38 fList[i-1]->clipRegion(fCanvasData[i-1].requiredClip);
39 }
40 }
41 SkASSERT(fList.count() == fCanvasData.count());
42 }
43
removeAll()44 void SkCanvasStack::removeAll() {
45 fCanvasData.reset();
46 this->INHERITED::removeAll();
47 }
48
49 /**
50 * Traverse all canvases (e.g. layers) the stack and ensure that they are clipped
51 * to their bounds and that the area covered by any canvas higher in the stack is
52 * also clipped out.
53 */
clipToZOrderedBounds()54 void SkCanvasStack::clipToZOrderedBounds() {
55 SkASSERT(fList.count() == fCanvasData.count());
56 for (int i = 0; i < fList.count(); ++i) {
57 fList[i]->clipRegion(fCanvasData[i].requiredClip, SkRegion::kIntersect_Op);
58 }
59 }
60
61 ////////////////////////////////////////////////////////////////////////////////
62
63 /**
64 * We need to handle setMatrix specially as it overwrites the matrix in each
65 * canvas unlike all other matrix operations (i.e. translate, scale, etc) which
66 * just pre-concatenate with the existing matrix.
67 */
setMatrix(const SkMatrix & matrix)68 void SkCanvasStack::setMatrix(const SkMatrix& matrix) {
69 SkASSERT(fList.count() == fCanvasData.count());
70 for (int i = 0; i < fList.count(); ++i) {
71
72 SkMatrix tempMatrix = matrix;
73 tempMatrix.postTranslate(SkIntToScalar(-fCanvasData[i].origin.x()),
74 SkIntToScalar(-fCanvasData[i].origin.y()));
75 fList[i]->setMatrix(tempMatrix);
76 }
77 this->SkCanvas::setMatrix(matrix);
78 }
79
clipRect(const SkRect & r,SkRegion::Op op,bool aa)80 bool SkCanvasStack::clipRect(const SkRect& r, SkRegion::Op op, bool aa) {
81 bool result = this->INHERITED::clipRect(r, op, aa);
82 this->clipToZOrderedBounds();
83 return result;
84 }
85
clipRRect(const SkRRect & rr,SkRegion::Op op,bool aa)86 bool SkCanvasStack::clipRRect(const SkRRect& rr, SkRegion::Op op, bool aa) {
87 bool result = this->INHERITED::clipRRect(rr, op, aa);
88 this->clipToZOrderedBounds();
89 return result;
90 }
91
clipPath(const SkPath & p,SkRegion::Op op,bool aa)92 bool SkCanvasStack::clipPath(const SkPath& p, SkRegion::Op op, bool aa) {
93 bool result = this->INHERITED::clipPath(p, op, aa);
94 this->clipToZOrderedBounds();
95 return result;
96 }
97
clipRegion(const SkRegion & deviceRgn,SkRegion::Op op)98 bool SkCanvasStack::clipRegion(const SkRegion& deviceRgn, SkRegion::Op op) {
99 SkASSERT(fList.count() == fCanvasData.count());
100 for (int i = 0; i < fList.count(); ++i) {
101 SkRegion tempRegion;
102 deviceRgn.translate(-fCanvasData[i].origin.x(),
103 -fCanvasData[i].origin.y(), &tempRegion);
104 tempRegion.op(fCanvasData[i].requiredClip, SkRegion::kIntersect_Op);
105 fList[i]->clipRegion(tempRegion, op);
106 }
107 return this->SkCanvas::clipRegion(deviceRgn, op);
108 }
109