app_server: Implement more composition modes

* Use agg::comp_op classes to blend pixels. * Subpixel path not implemented. * Needed by WebKit. * Implements #10274. Change-Id: I07b0002196fd0a05fc100bd9f6d703c33cadc85b Reviewed-on: https://review.haiku-os.org/c/haiku/+/2932 Reviewed-by: X512 <[email protected]> Reviewed-by: Adrien Destugues <[email protected]>
2020-06-29 14:07:42 +00:00
parent cc30c791bd
commit 97bd6fe8d4
23 changed files with 563 additions and 15 deletions
@@ -111,3 +111,204 @@

 	\since BeOS R3
 */
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_SOURCE_OVER
+
+	Draws source over destination preserving transparency. Same as
+	\c B_ALPHA_COMPOSITE.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE_OVER.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_SOURCE_IN
+
+	Draws source only where destination is not transparent.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE_IN.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_SOURCE_OUT
+
+	Draws source only where destination is transparent.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE_OUT.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_SOURCE_ATOP
+
+	Draws source only where destination is not transparent. Colors from both
+	are used in the result.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE_ATOP.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_DESTINATION_OVER
+
+	Draws source where destination is transparent, making it appear as if it
+	is drawn behind.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION_OVER.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_DESTINATION_IN
+
+	Blends source alpha channel with destination.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION_IN.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_DESTINATION_OUT
+
+	Blends inverse of source alpha channel with destination. Result appears as
+	if source was cut out of destination.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION_OUT.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_DESTINATION_ATOP
+
+	Draws source only where it is not transparent. Destination is blended on
+	top of it. Colors from both are used in the result.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION_ATOP.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_XOR
+
+	Result is transparent only where both source and destination are transparent
+	or opaque.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_XOR.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_CLEAR
+
+	Erases destination to full transparency, regardless of source alpha value.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_CLEAR.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_DIFFERENCE
+
+	Subtracts both inputs in a way that always yields positive result.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_DIFFERENCE.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_LIGHTEN
+
+	Retains lighter pixels of both inputs.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_LIGHTEN.png "Result"
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\var alpha_function B_ALPHA_COMPOSITE_DARKEN
+
+	Retains darker pixels of both inputs.
+
+	\image{inline} html B_ALPHA_COMPOSITE_SOURCE.png "Source"
+	->
+	\image{inline} html B_ALPHA_COMPOSITE_DESTINATION.png "Destination"
+	=
+	\image{inline} html B_ALPHA_COMPOSITE_DARKEN.png "Result"
+
+	\since Haiku R1
+*/
@@ -2124,9 +2124,11 @@ SetViewColor(Parent()->ViewColor());
 	\param alphaFunc Set to one of the following:
 	- \c B_ALPHA_OVERLAY Used for drawing a image with transparency over an opaque
 	     background.
-	- \c B_ALPHA_COMPOSITE Used to composite two or more transparent images
+	- \c B_ALPHA_COMPOSITE_* Used to composite two or more transparent images
 	     together offscreen to produce a new image drawn using
-		 \c B_ALPHA_OVERLAY mode.
+	     \c B_ALPHA_OVERLAY mode.
+	\note Modes other than \c B_ALPHA_OVERLAY and \c B_ALPHA_COMPOSITE work
+	      only with \c B_PIXEL_ALPHA.

 	\since BeOS R5
 */