We often rgn-diff an area >= the other rgn. now we detect that and return empty

We do this when we update our devices in SkCanvas.cpp
Review URL: https://codereview.appspot.com/6249073

git-svn-id: http://skia.googlecode.com/svn/trunk@4101 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 16 insertions, 2 deletions

diff --git a/include/core/SkRect.h b/include/core/SkRect.h
index e055c3d70b..83ef2df35c 100644
--- a/include/core/SkRect.h
+++ b/include/core/SkRect.h
@@ -206,6 +206,10 @@ struct SK_API SkIRect {
                fRight >= right && fBottom >= bottom;
     }
     
+    bool containsNoEmptyCheck(const SkIRect& r) const {
+        return containsNoEmptyCheck(r.fLeft, r.fTop, r.fRight, r.fBottom);
+    }
+    
     /** If r intersects this rectangle, return true and set this rectangle to that
         intersection, otherwise return false and do not change this rectangle.
         If either rectangle is empty, do nothing and return false.
@@ -273,10 +277,20 @@ struct SK_API SkIRect {
     }
     
     /** Returns true if a and b are not empty, and they intersect
-    */
+     */
     static bool Intersects(const SkIRect& a, const SkIRect& b) {
         return  !a.isEmpty() && !b.isEmpty() &&              // check for empties
-                a.fLeft < b.fRight && b.fLeft < a.fRight &&
+        a.fLeft < b.fRight && b.fLeft < a.fRight &&
+        a.fTop < b.fBottom && b.fTop < a.fBottom;
+    }
+    
+    /**
+     *  Returns true if a and b intersect. debug-asserts that neither are empty.
+     */
+    static bool IntersectsNoEmptyCheck(const SkIRect& a, const SkIRect& b) {
+        SkASSERT(!a.isEmpty());
+        SkASSERT(!b.isEmpty());
+        return  a.fLeft < b.fRight && b.fLeft < a.fRight &&
                 a.fTop < b.fBottom && b.fTop < a.fBottom;
     }