Bug 1208829 - Add utilities for converting between typed and untyped regions. r=mstange

--HG--
extra : source : 255d765deaf106955514b9875e27d1dc6446f211

gfx/src/nsRegion.h

@@ -729,6 +729,10 @@ public:
     return This();
   }
 
+  // Prefer using TransformTo<TargetUnits>(region) from UnitTransforms.h,
+  // as applying the transform should typically change the unit system.
+  // TODO(botond): Move this to IntRegionTyped and disable it for
+  //               unit != UnknownUnits.
   Derived& Transform (const mozilla::gfx::Matrix4x4 &aTransform)
   {
     mImpl.Transform(aTransform);

layout/base/UnitTransforms.h

@@ -9,6 +9,7 @@
 
 #include "Units.h"
 #include "mozilla/gfx/Matrix.h"
+#include "nsRegion.h"
 
 namespace mozilla {
 
@@ -78,6 +79,10 @@ template <class TargetUnits, class SourceUnits>
 gfx::IntMarginTyped<TargetUnits> ViewAs(const gfx::IntMarginTyped<SourceUnits>& aMargin, PixelCastJustification) {
   return gfx::IntMarginTyped<TargetUnits>(aMargin.top, aMargin.right, aMargin.bottom, aMargin.left);
 }
+template <class TargetUnits, class SourceUnits>
+gfx::IntRegionTyped<TargetUnits> ViewAs(const gfx::IntRegionTyped<SourceUnits>& aRegion, PixelCastJustification) {
+  return gfx::IntRegionTyped<TargetUnits>::FromUnknownRegion(aRegion.ToUnknownRegion());
+}
 template <class NewTargetUnits, class OldTargetUnits, class SourceUnits>
 gfx::ScaleFactor<SourceUnits, NewTargetUnits> ViewTargetAs(
     const gfx::ScaleFactor<SourceUnits, OldTargetUnits>& aScaleFactor,
@@ -112,6 +117,10 @@ template <class TargetUnits>
 gfx::IntRectTyped<TargetUnits> ViewAs(const nsIntRect& aRect) {
   return gfx::IntRectTyped<TargetUnits>(aRect.x, aRect.y, aRect.width, aRect.height);
 }
+template <class TargetUnits>
+gfx::IntRegionTyped<TargetUnits> ViewAs(const nsIntRegion& aRegion) {
+  return gfx::IntRegionTyped<TargetUnits>::FromUnknownRegion(aRegion);
+}
 
 // Convenience functions for transforming an entity from one strongly-typed
 // coordinate system to another using the provided transformation matrix.
@@ -140,6 +149,12 @@ static gfx::IntRectTyped<TargetUnits> TransformTo(const gfx::Matrix4x4& aTransfo
   gfx::Rect rect(aRect.ToUnknownRect());
   return RoundedToInt(ViewAs<TargetUnits>(aTransform.TransformBounds(rect)));
 }
+template <typename TargetUnits, typename SourceUnits>
+static gfx::IntRegionTyped<TargetUnits> TransformTo(const gfx::Matrix4x4& aTransform,
+                                                    const gfx::IntRegionTyped<SourceUnits>& aRegion)
+{
+  return ViewAs<TargetUnits>(aRegion.ToUnknownRegion().Transform(aTransform));
+}
 
 // Transform |aVector|, which is anchored at |aAnchor|, by the given transform
 // matrix, yielding a point in |TargetUnits|.