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@11081 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 52 insertions, 0 deletions

diff --git a/src/utils/SkCanvasStack.h b/src/utils/SkCanvasStack.h
new file mode 100644
index 0000000000..2137d308b8
--- /dev/null
+++ b/src/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