BRegion: add ScaleBy method.

* Is there a reason to not have it?

headers/os/interface/Region.h

@@ -59,6 +59,7 @@ public:
 
 			void				OffsetBy(const BPoint& point);
 			void				OffsetBy(int32 x, int32 y);
+			void				ScaleBy(float x, float y);
 
 			void				MakeEmpty();
 

headers/private/interface/clipping.h

@@ -81,6 +81,16 @@ offset_rect(clipping_rect &rect, int32 x, int32 y)
 }
 
 
+static inline void
+scale_rect(clipping_rect& rect, float x, float y)
+{
+	rect.left = (int)(rect.left * x);
+	rect.top = (int)(rect.top * y);
+	rect.right = (int)(rect.right * x);
+	rect.bottom = (int)(rect.bottom * y);
+}
+
+
 // Converts the given clipping_rect to a BRect
 static inline BRect
 to_BRect(const clipping_rect &rect)

src/kits/interface/Region.cpp

@@ -306,6 +306,23 @@ BRegion::OffsetBy(int32 x, int32 y)
 }
 
 
+void
+BRegion::ScaleBy(float x, float y)
+{
+	if (x == 1.0 && y == 1.0)
+		return;
+
+	if (fCount > 0) {
+		if (fData != &fBounds) {
+			for (int32 i = 0; i < fCount; i++)
+				scale_rect(fData[i], x, y);
+		}
+
+		scale_rect(fBounds, x, y);
+	}
+}
+
+
 // Empties the region, so that it doesn't include any rect, and invalidates
 // its bounds.
 void