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      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 
     10 SkCanvasStack::SkCanvasStack(int width, int height)
     11         : INHERITED(width, height) {}
     12 
     13 SkCanvasStack::~SkCanvasStack() {
     14     this->removeAll();
     15 }
     16 
     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 
     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  */
     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  */
     68 void 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 
     80 void SkCanvasStack::onClipRect(const SkRect& r, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
     81     this->INHERITED::onClipRect(r, op, edgeStyle);
     82     this->clipToZOrderedBounds();
     83 }
     84 
     85 void SkCanvasStack::onClipRRect(const SkRRect& rr, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
     86     this->INHERITED::onClipRRect(rr, op, edgeStyle);
     87     this->clipToZOrderedBounds();
     88 }
     89 
     90 void SkCanvasStack::onClipPath(const SkPath& p, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
     91     this->INHERITED::onClipPath(p, op, edgeStyle);
     92     this->clipToZOrderedBounds();
     93 }
     94 
     95 void 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