app_server: add Squash method in DrawState

* New method DrawState::Squash() uses the combined scale, origin and
  transform as the state's own scale, origin, transform.

  This can be used when making copies of DrawStates which have
  previous states below them in the state stack. The top of stack
  DrawState can be copied, squashed and then used just like the
  original one with the whole stack below it (except of course
  when trying to pop off any earlier state).

src/servers/app/DrawState.cpp

@@ -370,6 +370,19 @@ DrawState::SetTransform(BAffineTransform transform)
 }
 
 
+DrawState*
+DrawState::Squash()
+{
+	DrawState* const squashedState = new DrawState(*this);
+
+	squashedState->fOrigin = fCombinedOrigin;
+	squashedState->fScale = fCombinedScale;
+	squashedState->fTransform = fCombinedTransform;
+
+	return squashedState;
+}
+
+
 void
 DrawState::SetClippingRegion(const BRegion* region)
 {

src/servers/app/DrawState.h

@@ -69,6 +69,8 @@ public:
 		BAffineTransform	CombinedTransform() const
 								{ return fCombinedTransform; }
 
+		DrawState*			Squash();
+
 							// additional clipping as requested by client
 		void				SetClippingRegion(const BRegion* region);