til_fb: introduce a fragment texture source

Idea here is to provide texture sources for obtaining pixel
colors at the til_fb_put_pixel/fill drawing API, making it
possible for at least overlayable modules to serve as
mask/stencil operators where their drawn areas are populated by
the contents of another fragment produced dynamically,
potentially by other modules altogether.

This commit adds a texture=modulename option to the compose
module for specifying if a texture should be used when
compositing, excepting and defaulting to "none" for disabling
texturing.

A future commit should expand this compose option to accept a
potential list of modules for composing the texture in the same
way as the main layers= list functions.

Something this all immediately makes clear is the need for
a better settings syntax, probably in the form of all module
setting specifiers optionally being followed by a squence
of settings, with support for escaping to handle nested
situations.

1 files changed, 14 insertions, 11 deletions

diff --git a/src/modules/montage/montage.c b/src/modules/montage/montage.c
index 8444616..65aabe6 100644
--- a/src/modules/montage/montage.c
+++ b/src/modules/montage/montage.c
@@ -141,17 +141,20 @@ static int montage_fragment_tile(const til_fb_fragment_t *fragment, unsigned til
 	xoff = x * tile_width;
 	yoff = y * tile_height;
 
-	res_fragment->buf = fragment->buf + (yoff * fragment->pitch) + xoff;
-	res_fragment->x = 0;					/* fragment is a new frame */
-	res_fragment->y = 0;					/* fragment is a new frame */
-	res_fragment->width = MIN(fragment->width - xoff, tile_width);
-	res_fragment->height = MIN(fragment->height - yoff, tile_height);
-	res_fragment->frame_width = res_fragment->width;	/* fragment is a new frame */
-	res_fragment->frame_height = res_fragment->height;	/* fragment is a new frame */
-	res_fragment->stride = fragment->stride + (fragment->width - res_fragment->width);
-	res_fragment->pitch = fragment->pitch;
-	res_fragment->number = number;
-	res_fragment->cleared = fragment->cleared;
+	*res_fragment = (til_fb_fragment_t){
+				.texture = fragment->texture,
+				.buf = fragment->buf + (yoff * fragment->pitch) + xoff,
+				.x = 0,								/* fragment is a new frame */
+				.y = 0,								/* fragment is a new frame */
+				.width = MIN(fragment->width - xoff, tile_width),
+				.height = MIN(fragment->height - yoff, tile_height),
+				.frame_width = MIN(fragment->width - xoff, tile_width),		/* fragment is a new frame */
+				.frame_height = MIN(fragment->height - yoff, tile_height),	/* fragment is a new frame */
+				.stride = fragment->stride + (fragment->width - MIN(fragment->width - xoff, tile_width)),
+				.pitch = fragment->pitch,
+				.number = number,
+				.cleared = fragment->cleared,
+			};
 
 	return 1;
 }