add gpu backend (not hooked up yet)



git-svn-id: http://skia.googlecode.com/svn/trunk@649 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/include/GrClipIterator.h b/gpu/include/GrClipIterator.h
new file mode 100644
index 0000000..d1fe4dd
--- /dev/null
+++ b/gpu/include/GrClipIterator.h
@@ -0,0 +1,81 @@
+/*
+    Copyright 2010 Google Inc.
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+         http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+ */
+
+
+#ifndef GrClipIterator_DEFINED
+#define GrClipIterator_DEFINED
+
+#include "GrRect.h"
+
+class GrClipIterator {
+public:
+    GrClipIterator() : fNeedBounds(true) {}
+    virtual ~GrClipIterator() {}
+
+    /**
+     *  Returns true if there are no more rects to process
+     */
+    virtual bool isDone() = 0;
+
+    /**
+     *  Rewind the iterate to replay the set of rects again
+     */
+    virtual void rewind() = 0;
+
+    /**
+     *  Return the current rect. It is an error to call this when done() is true
+     */
+    virtual void getRect(GrIRect*) = 0;
+
+    /**
+     *  Call to move to the next rect in the set
+     */
+    virtual void next() = 0;
+
+    /**
+     *  Set bounds to be the bounds of the clip.
+     */
+    virtual void computeBounds(GrIRect* bounds) = 0;
+
+    /**
+     *  Subclass should call this whenever their underlying bounds has changed.
+     */
+    void invalidateBoundsCache() { fNeedBounds = true; }
+
+    const GrIRect& getBounds() {
+        if (fNeedBounds) {
+            this->computeBounds(&fBounds);
+            fNeedBounds = false;
+        }
+        return fBounds;
+    }
+
+private:
+    GrIRect fBounds;
+    bool    fNeedBounds;
+};
+
+/**
+ *  Call to rewind iter, first checking to see if iter is NULL
+ */
+static inline void GrSafeRewind(GrClipIterator* iter) {
+    if (iter) {
+        iter->rewind();
+    }
+}
+
+#endif
+