1 files changed, 117 insertions, 0 deletions
diff --git a/gfx/skia/skia/src/utils/SkCanvasStack.cpp b/gfx/skia/skia/src/utils/SkCanvasStack.cpp
new file mode 100644
index 0000000000..ea3918b8bc
--- /dev/null
+++ b/gfx/skia/skia/src/utils/SkCanvasStack.cpp
@@ -0,0 +1,117 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "src/utils/SkCanvasStack.h"
+
+#include "include/core/SkRect.h"
+#include "include/core/SkScalar.h"
+#include "include/core/SkShader.h"
+#include "include/private/base/SkTDArray.h"
+#include <utility>
+
+class SkPath;
+class SkRRect;
+
+SkCanvasStack::SkCanvasStack(int width, int height)
+        : INHERITED(width, height) {}
+
+SkCanvasStack::~SkCanvasStack() {
+    this->removeAll();
+}
+
+void SkCanvasStack::pushCanvas(std::unique_ptr<SkCanvas> canvas, const SkIPoint& origin) {
+    if (canvas) {
+        // compute the bounds of this canvas
+        const SkIRect canvasBounds = SkIRect::MakeSize(canvas->getBaseLayerSize());
+
+        // push the canvas onto the stack
+        this->INHERITED::addCanvas(canvas.get());
+
+        // push the canvas data onto the stack
+        CanvasData* data = &fCanvasData.push_back();
+        data->origin = origin;
+        data->requiredClip.setRect(canvasBounds);
+        data->ownedCanvas = std::move(canvas);
+
+        // subtract this region from the canvas objects already on the stack.
+        // This ensures they do not draw into the space occupied by the layers
+        // above them.
+        for (int i = fList.size() - 1; i > 0; --i) {
+            SkIRect localBounds = canvasBounds;
+            localBounds.offset(origin - fCanvasData[i-1].origin);
+
+            fCanvasData[i-1].requiredClip.op(localBounds, SkRegion::kDifference_Op);
+            fList[i-1]->clipRegion(fCanvasData[i-1].requiredClip);
+        }
+    }
+    SkASSERT(fList.size() == fCanvasData.size());
+}
+
+void SkCanvasStack::removeAll() {
+    this->INHERITED::removeAll();   // call the baseclass *before* we actually delete the canvases
+    fCanvasData.clear();
+}
+
+/**
+ * Traverse all canvases (e.g. layers) the stack and ensure that they are clipped
+ * to their bounds and that the area covered by any canvas higher in the stack is
+ * also clipped out.
+ */
+void SkCanvasStack::clipToZOrderedBounds() {
+    SkASSERT(fList.size() == fCanvasData.size());
+    for (int i = 0; i < fList.size(); ++i) {
+        fList[i]->clipRegion(fCanvasData[i].requiredClip);
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * We need to handle setMatrix specially as it overwrites the matrix in each
+ * canvas unlike all other matrix operations (i.e. translate, scale, etc) which
+ * just pre-concatenate with the existing matrix.
+ */
+void SkCanvasStack::didSetM44(const SkM44& mx) {
+    SkASSERT(fList.size() == fCanvasData.size());
+    for (int i = 0; i < fList.size(); ++i) {
+        fList[i]->setMatrix(SkM44::Translate(SkIntToScalar(-fCanvasData[i].origin.x()),
+                                             SkIntToScalar(-fCanvasData[i].origin.y())) * mx);
+    }
+    this->SkCanvas::didSetM44(mx);
+}
+
+void SkCanvasStack::onClipRect(const SkRect& r, SkClipOp op, ClipEdgeStyle edgeStyle) {
+    this->INHERITED::onClipRect(r, op, edgeStyle);
+    this->clipToZOrderedBounds();
+}
+
+void SkCanvasStack::onClipRRect(const SkRRect& rr, SkClipOp op, ClipEdgeStyle edgeStyle) {
+    this->INHERITED::onClipRRect(rr, op, edgeStyle);
+    this->clipToZOrderedBounds();
+}
+
+void SkCanvasStack::onClipPath(const SkPath& p, SkClipOp op, ClipEdgeStyle edgeStyle) {
+    this->INHERITED::onClipPath(p, op, edgeStyle);
+    this->clipToZOrderedBounds();
+}
+
+void SkCanvasStack::onClipShader(sk_sp<SkShader> cs, SkClipOp op) {
+    this->INHERITED::onClipShader(std::move(cs), op);
+    // we don't change the "bounds" of the clip, so we don't need to update zorder
+}
+
+void SkCanvasStack::onClipRegion(const SkRegion& deviceRgn, SkClipOp op) {
+    SkASSERT(fList.size() == fCanvasData.size());
+    for (int i = 0; i < fList.size(); ++i) {
+        SkRegion tempRegion;
+        deviceRgn.translate(-fCanvasData[i].origin.x(),
+                            -fCanvasData[i].origin.y(), &tempRegion);
+        tempRegion.op(fCanvasData[i].requiredClip, SkRegion::kIntersect_Op);
+        fList[i]->clipRegion(tempRegion, op);
+    }
+    this->SkCanvas::onClipRegion(deviceRgn, op);
+}