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
10SkCanvasStack::SkCanvasStack(int width, int height)
11        : INHERITED(width, height) {}
12
13SkCanvasStack::~SkCanvasStack() {
14    this->removeAll();
15}
16
17void 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
44void 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 */
54void 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 */
68void SkCanvasStack::didSetMatrix(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::didSetMatrix(matrix);
78}
79
80void SkCanvasStack::onClipRect(const SkRect& r, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
81    this->INHERITED::onClipRect(r, op, edgeStyle);
82    this->clipToZOrderedBounds();
83}
84
85void SkCanvasStack::onClipRRect(const SkRRect& rr, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
86    this->INHERITED::onClipRRect(rr, op, edgeStyle);
87    this->clipToZOrderedBounds();
88}
89
90void SkCanvasStack::onClipPath(const SkPath& p, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
91    this->INHERITED::onClipPath(p, op, edgeStyle);
92    this->clipToZOrderedBounds();
93}
94
95void SkCanvasStack::onClipRegion(const SkRegion& deviceRgn, SkRegion::Op op) {
96    SkASSERT(fList.count() == fCanvasData.count());
97    for (int i = 0; i < fList.count(); ++i) {
98        SkRegion tempRegion;
99        deviceRgn.translate(-fCanvasData[i].origin.x(),
100                            -fCanvasData[i].origin.y(), &tempRegion);
101        tempRegion.op(fCanvasData[i].requiredClip, SkRegion::kIntersect_Op);
102        fList[i]->clipRegion(tempRegion, op);
103    }
104    this->SkCanvas::onClipRegion(deviceRgn, op);
105}
106