AlphaMasks: Use correct DrawState when playing picture

The current drawing state when the picture starts playing is the base
state that drawing commands in the picture itself should not be able to
modify. In the ClipToPicture test, the nested state test now at least
draws the last picture at the correctly scaled location.

src/servers/app/AlphaMask.cpp

@@ -116,9 +116,9 @@ AlphaMask::_RenderPicture() const
 		return NULL;
 	}
 
-	engine->SetDrawState(&fDrawState);
+	OffscreenContext context(engine, fDrawState);
+	context.PushState();
 
-	OffscreenContext context(engine);
 	if (engine->LockParallelAccess()) {
 		// FIXME ConstrainClippingRegion docs says passing NULL disables
 		// all clipping. This doesn't work and will crash in Painter.
@@ -128,6 +128,8 @@ AlphaMask::_RenderPicture() const
 		fPicture->Play(&context);
 		engine->UnlockParallelAccess();
 	}
+
+	context.PopState();
 	delete engine;
 
 	if (!fInverse)

src/servers/app/DrawingContext.cpp

@@ -23,12 +23,20 @@
 #include <GradientConic.h>
 #include <Region.h>
 
+#include "DrawingEngine.h"
 #include "DrawState.h"
 
 
 DrawingContext::DrawingContext()
 	:
-	fDrawState(new (std::nothrow) DrawState)
+	fDrawState(new(std::nothrow) DrawState())
+{
+}
+
+
+DrawingContext::DrawingContext(const DrawState& state)
+	:
+	fDrawState(new(std::nothrow) DrawState(state))
 {
 }
 
@@ -304,3 +312,14 @@ DrawingContext::ConvertFromScreenForDrawing(BPoint* point) const
 }
 
 
+// #pragma mark - OffscreenContext
+
+
+OffscreenContext::OffscreenContext(DrawingEngine* engine,
+		const DrawState& state)
+	:
+	DrawingContext(state),
+	fDrawingEngine(engine)
+{
+	fDrawingEngine->SetDrawState(fDrawState);
+}

src/servers/app/DrawingContext.h

@@ -30,6 +30,7 @@ class ServerPicture;
 class DrawingContext {
 public:
 							DrawingContext();
+							DrawingContext(const DrawState& state);
 	virtual					~DrawingContext();
 
 			status_t		InitCheck() const;
@@ -83,9 +84,8 @@ protected:
 
 class OffscreenContext: public DrawingContext {
 public:
-							OffscreenContext(DrawingEngine* engine)
-								: fDrawingEngine(engine)
-							{};
+							OffscreenContext(DrawingEngine* engine,
+								const DrawState& state);
 
 							// Screen and View coordinates are the same for us.
 							// DrawState already takes care of World<>View