Build fix.

Some code in a just merged patch needs another one that's still being
discussed on Gerrit. Extract just the parts we need to get things
building again.

src/servers/app/Canvas.cpp

@@ -57,7 +57,7 @@ Canvas::~Canvas()
 status_t
 Canvas::InitCheck() const
 {
-	if (fDrawState == NULL)
+	if (fDrawState.Get() == NULL)
 		return B_NO_MEMORY;
 
 	return B_OK;
@@ -67,9 +67,12 @@ Canvas::InitCheck() const
 void
 Canvas::PushState()
 {
-	DrawState* newState = fDrawState->PushState();
+	DrawState* previous = fDrawState.Detach();
-	if (newState)
+	DrawState* newState = previous->PushState();
-		fDrawState = newState;
+	if (newState == NULL)
+		newState = previous;
+
+	fDrawState.SetTo(newState);
 }
 
 
@@ -81,7 +84,7 @@ Canvas::PopState()
 
 	bool rebuildClipping = fDrawState->HasAdditionalClipping();
 
-	fDrawState = fDrawState->PopState();
+	fDrawState.SetTo(fDrawState->PopState());
 
 	// rebuild clipping
 	// (the clipping from the popped state is not effective anymore)
@@ -93,7 +96,7 @@ Canvas::PopState()
 void
 Canvas::SetDrawState(DrawState* newState)
 {
-	fDrawState = newState;
+	fDrawState.SetTo(newState);
 }
 
 
@@ -293,14 +296,13 @@ OffscreenCanvas::OffscreenCanvas(DrawingEngine* engine,
 
 OffscreenCanvas::~OffscreenCanvas()
 {
-	delete fDrawState;
 }
 
 
 void
 OffscreenCanvas::ResyncDrawState()
 {
-	fDrawingEngine->SetDrawState(fDrawState);
+	fDrawingEngine->SetDrawState(fDrawState.Get());
 }
 
 

src/servers/app/Canvas.h

@@ -15,6 +15,7 @@
 #define CANVAS_H
 
 
+#include <AutoDeleter.h>
 #include <Point.h>
 
 #include "SimpleTransform.h"
@@ -42,8 +43,9 @@ public:
 
 	virtual	void			PushState();
 	virtual	void			PopState();
-			DrawState*		CurrentState() const { return fDrawState; }
+			DrawState*		CurrentState() const { return fDrawState.Get(); }
 			void			SetDrawState(DrawState* newState);
+			DrawState*		DetachDrawState() { return fDrawState.Detach(); }
 
 			void			SetDrawingOrigin(BPoint origin);
 			BPoint			DrawingOrigin() const;
@@ -83,7 +85,8 @@ protected:
 								SimpleTransform& transform) const = 0;
 
 protected:
-			DrawState*		fDrawState;
+			ObjectDeleter<DrawState>
+							fDrawState;
 };