View: provide the transform between different coordinate spaces

There's currently no way for an application to convert between view and
drawing coordinates with a drawing states stack without keeping track of
all the transformations itself, which is not very convenient for helper
or library functions.

Handle other spaces too, for good measure.

Change-Id: Ic8404a1c111e273fff1eebf2f9f59f58246b796c
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5775
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: waddlesplash <[email protected]>

headers/os/interface/View.h

@@ -70,6 +70,16 @@ enum {
 	B_FONT_ALL							= 0x000001FF
 };
 
+typedef enum {
+	B_CURRENT_STATE_COORDINATES,
+	B_PREVIOUS_STATE_COORDINATES,
+	B_VIEW_COORDINATES,
+	B_PARENT_VIEW_DRAW_COORDINATES,
+	B_PARENT_VIEW_COORDINATES,
+	B_WINDOW_COORDINATES,
+	B_SCREEN_COORDINATES
+} coordinate_space;
+
 // view flags
 const uint32 B_FULL_UPDATE_ON_RESIZE	= 0x80000000UL;	/* 31 */
 const uint32 _B_RESERVED1_				= 0x40000000UL;	/* 30 */
@@ -324,6 +334,8 @@ public:
 			void				ScaleBy(double x, double y);
 			void				RotateBy(double angleRadians);
 
+			BAffineTransform	TransformTo(coordinate_space basis) const;
+
 			void				PushState();
 			void				PopState();
 

headers/private/app/ServerProtocol.h

@@ -358,6 +358,7 @@ enum {
 	// transformation in addition to origin/scale
 	AS_VIEW_SET_TRANSFORM,
 	AS_VIEW_GET_TRANSFORM,
+	AS_VIEW_GET_PARENT_COMPOSITE,
 
 	AS_VIEW_AFFINE_TRANSLATE,
 	AS_VIEW_AFFINE_SCALE,

headers/private/interface/ViewPrivate.h

@@ -45,6 +45,7 @@ enum {
 	B_VIEW_WHICH_VIEW_COLOR_BIT	= 0x00100000,
 	B_VIEW_WHICH_LOW_COLOR_BIT	= 0x00200000,
 	B_VIEW_WHICH_HIGH_COLOR_BIT	= 0x00400000,
+	B_VIEW_PARENT_COMPOSITE_BIT	= 0x00800000,
 
 	B_VIEW_ALL_BITS				= 0x00ffffff,
 
@@ -131,6 +132,11 @@ class ViewState {
 		float				scale;
 		BAffineTransform	transform;
 
+		// composite transformation stack
+		BPoint				parent_composite_origin;
+		float				parent_composite_scale;
+		BAffineTransform	parent_composite_transform;
+
 		// line modes
 		join_mode			line_join;
 		cap_mode			line_cap;