app_server/Interface Kit: add new clipping API

* Add new clipping API for rectangles (ClipToRect, ClipToInverseRect)
  and shapes (ClipToShape, ClipToInverseShape)

* Works with affine transforms and automatically switches from fast
  region-based clipping to alpha-mask based clipping as necessary.

* Always self-intersecting, i.e. no state push required to further
  narrow down the clipping region. All of the 4 new methods can be
  mixed in any order.

headers/private/interface/PictureDataWriter.h

@@ -96,6 +96,11 @@ public:
 									const int32& token);
 
 			status_t			WriteBlendLayer(Layer* layer);
+			status_t			WriteClipToRect(const BRect& rect,
+									bool inverse);
+			status_t			WriteClipToShape(int32 opCount,
+									const void* opList, int32 ptCount,
+									const void* ptList, bool inverse);
 
 protected:
 	// throw a status_t on error

headers/private/interface/PicturePlayer.h

@@ -85,6 +85,9 @@ struct picture_player_callbacks {
 		alpha_function alphaFunctionMode);
 	void (*set_transform)(void* userData, const BAffineTransform& transform);
 	void (*blend_layer)(void* userData, Layer* layer);
+	void (*clip_to_rect)(void* userData, const BRect& rect, bool inverse);
+	void (*clip_to_shape)(void* userData, int32 opCount, const uint32 opList[],
+		int32 ptCount, const BPoint ptList[], bool inverse);
 };
 
 

headers/private/interface/PictureProtocol.h

@@ -29,6 +29,8 @@ enum {
 	B_PIC_PUSH_STATE			= 0x0203,
 	B_PIC_POP_STATE				= 0x0204,
 	B_PIC_CLEAR_CLIPPING_RECTS	= 0x0205,
+	B_PIC_CLIP_TO_RECT			= 0x0206,
+	B_PIC_CLIP_TO_SHAPE			= 0x0207,
 
 	B_PIC_SET_ORIGIN			= 0x0300,
 	B_PIC_SET_PEN_LOCATION		= 0x0301,