Add SkCanvasStack and update the Canvas utilities to use it.
BUG=
R=reed@google.com
Review URL: https://codereview.chromium.org/23865004
git-svn-id: http://skia.googlecode.com/svn/trunk/src@11081 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/utils/SkCanvasStack.cpp b/utils/SkCanvasStack.cpp
new file mode 100644
index 0000000..db5a8b2
--- /dev/null
+++ b/utils/SkCanvasStack.cpp
@@ -0,0 +1,108 @@
+
+/*
+ * 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 "SkCanvasStack.h"
+
+SkCanvasStack::SkCanvasStack(int width, int height)
+ : INHERITED(width, height) {}
+
+SkCanvasStack::~SkCanvasStack() {
+ this->removeAll();
+}
+
+void SkCanvasStack::pushCanvas(SkCanvas* canvas, const SkIPoint& origin) {
+ if (canvas) {
+ // compute the bounds of this canvas
+ const SkIRect canvasBounds = SkIRect::MakeSize(canvas->getDeviceSize());
+
+ // push the canvas onto the stack
+ this->INHERITED::addCanvas(canvas);
+
+ // push the canvas data onto the stack
+ CanvasData* data = &fCanvasData.push_back();
+ data->origin = origin;
+ data->requiredClip.setRect(canvasBounds);
+
+ // 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.count() - 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-i]->clipRegion(fCanvasData[i-1].requiredClip);
+ }
+ }
+ SkASSERT(fList.count() == fCanvasData.count());
+}
+
+void SkCanvasStack::removeAll() {
+ fCanvasData.reset();
+ this->INHERITED::removeAll();
+}
+
+/**
+ * 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.count() == fCanvasData.count());
+ for (int i = 0; i < fList.count(); ++i) {
+ fList[i]->clipRegion(fCanvasData[i].requiredClip, SkRegion::kIntersect_Op);
+ }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * 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::setMatrix(const SkMatrix& matrix) {
+ SkASSERT(fList.count() == fCanvasData.count());
+ for (int i = 0; i < fList.count(); ++i) {
+
+ SkMatrix tempMatrix = matrix;
+ tempMatrix.postTranslate(SkIntToScalar(-fCanvasData[i].origin.x()),
+ SkIntToScalar(-fCanvasData[i].origin.y()));
+ fList[i]->setMatrix(tempMatrix);
+ }
+ this->SkCanvas::setMatrix(matrix);
+}
+
+bool SkCanvasStack::clipRect(const SkRect& r, SkRegion::Op op, bool aa) {
+ bool result = this->INHERITED::clipRect(r, op, aa);
+ this->clipToZOrderedBounds();
+ return result;
+}
+
+bool SkCanvasStack::clipRRect(const SkRRect& rr, SkRegion::Op op, bool aa) {
+ bool result = this->INHERITED::clipRRect(rr, op, aa);
+ this->clipToZOrderedBounds();
+ return result;
+}
+
+bool SkCanvasStack::clipPath(const SkPath& p, SkRegion::Op op, bool aa) {
+ bool result = this->INHERITED::clipPath(p, op, aa);
+ this->clipToZOrderedBounds();
+ return result;
+}
+
+bool SkCanvasStack::clipRegion(const SkRegion& deviceRgn, SkRegion::Op op) {
+ SkASSERT(fList.count() == fCanvasData.count());
+ for (int i = 0; i < fList.count(); ++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);
+ }
+ return this->SkCanvas::clipRegion(deviceRgn, op);
+}
diff --git a/utils/SkCanvasStack.h b/utils/SkCanvasStack.h
new file mode 100644
index 0000000..2137d30
--- /dev/null
+++ b/utils/SkCanvasStack.h
@@ -0,0 +1,52 @@
+
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkCanvasStack_DEFINED
+#define SkCanvasStack_DEFINED
+
+#include "SkNWayCanvas.h"
+#include "SkTArray.h"
+
+class SkCanvasStack : public SkNWayCanvas {
+public:
+ SkCanvasStack(int width, int height);
+ virtual ~SkCanvasStack();
+
+ void pushCanvas(SkCanvas* canvas, const SkIPoint& origin);
+ virtual void removeAll() SK_OVERRIDE;
+
+ /*
+ * The following add/remove canvas methods are overrides from SkNWayCanvas
+ * that do not make sense in the context of our CanvasStack, but since we
+ * can share most of the other implementation of NWay we override those
+ * methods to be no-ops.
+ */
+ virtual void addCanvas(SkCanvas*) SK_OVERRIDE { SkASSERT(!"Invalid Op"); }
+ virtual void removeCanvas(SkCanvas*) SK_OVERRIDE { SkASSERT(!"Invalid Op"); }
+
+ virtual void setMatrix(const SkMatrix& matrix) SK_OVERRIDE;
+ virtual bool clipRect(const SkRect&, SkRegion::Op, bool) SK_OVERRIDE;
+ virtual bool clipRRect(const SkRRect&, SkRegion::Op, bool) SK_OVERRIDE;
+ virtual bool clipPath(const SkPath&, SkRegion::Op, bool) SK_OVERRIDE;
+ virtual bool clipRegion(const SkRegion& deviceRgn,
+ SkRegion::Op) SK_OVERRIDE;
+
+private:
+ void clipToZOrderedBounds();
+
+ struct CanvasData {
+ SkIPoint origin;
+ SkRegion requiredClip;
+ };
+
+ SkTArray<CanvasData> fCanvasData;
+
+ typedef SkNWayCanvas INHERITED;
+};
+
+#endif
diff --git a/utils/SkCanvasStateUtils.cpp b/utils/SkCanvasStateUtils.cpp
index c4232c2..cd79a44 100644
--- a/utils/SkCanvasStateUtils.cpp
+++ b/utils/SkCanvasStateUtils.cpp
@@ -9,7 +9,7 @@
#include "SkBitmapDevice.h"
#include "SkCanvas.h"
-#include "SkNWayCanvas.h"
+#include "SkCanvasStack.h"
#include "SkWriter32.h"
#define CANVAS_STATE_VERSION 1
@@ -316,18 +316,19 @@
return NULL;
}
- SkAutoTUnref<SkNWayCanvas> canvas(SkNEW_ARGS(SkNWayCanvas, (state->width, state->height)));
+ SkAutoTUnref<SkCanvasStack> canvas(SkNEW_ARGS(SkCanvasStack, (state->width, state->height)));
// setup the matrix and clip on the n-way canvas
setup_canvas_from_MC_state(state->mcState, canvas);
// Iterate over the layers and add them to the n-way canvas
- for (int i = 0; i < state->layerCount; ++i) {
+ for (int i = state->layerCount - 1; i >= 0; --i) {
SkAutoTUnref<SkCanvas> canvasLayer(create_canvas_from_canvas_layer(state->layers[i]));
if (!canvasLayer.get()) {
return NULL;
}
- canvas->addCanvas(canvasLayer.get());
+ canvas->pushCanvas(canvasLayer.get(), SkIPoint::Make(state->layers[i].x,
+ state->layers[i].y));
}
return canvas.detach();
