Introduce a new compositor architecture

Having spent the last dev cycle looking at how we could specialize the
compositors for various backends, we once again look for the
commonalities in order to reduce the duplication. In part this is
motivated by the idea that spans is a good interface for both the
existent GL backend and pixman, and so they deserve a dedicated
compositor. xcb/xlib target an identical rendering system and so they
should be using the same compositor, and it should be possible to run
that same compositor locally against pixman to generate reference tests.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

P.S. This brings massive upheaval (read breakage) I've tried delaying in
order to fix as many things as possible but now this one patch does far,
far, far too much. Apologies in advance for breaking your favourite
backend, but trust me in that the end result will be much better. :)

1 files changed, 59 insertions, 12 deletions

diff --git a/src/cairo-path-stroke-polygon.c b/src/cairo-path-stroke-polygon.c
index 3b8a67dae..9128a0037 100644
--- a/src/cairo-path-stroke-polygon.c
+++ b/src/cairo-path-stroke-polygon.c
@@ -104,6 +104,7 @@ within_tolerance (const cairo_point_t *p1,
 	      const cairo_point_t *p2,
 	      cairo_uint64_t tolerance)
 {
+    return FALSE;
     return _cairo_int64_lt (point_distance_sq (p1, p2), tolerance);
 }
 
@@ -115,6 +116,7 @@ contour_add_point (struct stroker *stroker,
     if (! within_tolerance (point, _cairo_contour_last_point (&c->contour),
 			stroker->contour_tolerance))
 	_cairo_contour_add_point (&c->contour, point);
+    //*_cairo_contour_last_point (&c->contour) = *point;
 }
 
 static void
@@ -789,7 +791,7 @@ outer_join (struct stroker *stroker,
 	     * Make sure the miter point line lies between the two
 	     * faces by comparing the slopes
 	     */
-	    if (1 || slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
+	    if (slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
 		slope_compare_sgn (fdx2, fdy2, mdx, mdy))
 	    {
 		cairo_point_t p;
@@ -1091,6 +1093,7 @@ line_to (void *closure,
     cairo_stroke_face_t start;
     cairo_point_t *p1 = &stroker->current_face.point;
     cairo_slope_t dev_slope;
+    int move_last = 0;
 
     stroker->has_initial_sub_path = TRUE;
 
@@ -1105,15 +1108,21 @@ line_to (void *closure,
     compute_face (p1, &dev_slope, stroker, &start);
 
     if (stroker->has_current_face) {
-	int clockwise = join_is_clockwise (&stroker->current_face, &start);
-	/* Join with final face from previous segment */
-	if (! within_tolerance (&stroker->current_face.ccw, &start.ccw,
-				stroker->contour_tolerance) ||
-	    ! within_tolerance (&stroker->current_face.cw, &start.cw,
-				stroker->contour_tolerance))
-	{
-	    outer_join (stroker, &stroker->current_face, &start, clockwise);
-	    inner_join (stroker, &stroker->current_face, &start, clockwise);
+	int clockwise = _cairo_slope_compare (&stroker->current_face.dev_vector,
+					      &start.dev_vector);
+	if (clockwise == 0) {
+	    move_last = 1;
+	} else {
+	    clockwise = clockwise < 0;
+	    /* Join with final face from previous segment */
+	    if (! within_tolerance (&stroker->current_face.ccw, &start.ccw,
+				    stroker->contour_tolerance) ||
+		! within_tolerance (&stroker->current_face.cw, &start.cw,
+				    stroker->contour_tolerance))
+	    {
+		outer_join (stroker, &stroker->current_face, &start, clockwise);
+		inner_join (stroker, &stroker->current_face, &start, clockwise);
+	    }
 	}
     } else {
 	if (! stroker->has_first_face) {
@@ -1134,8 +1143,13 @@ line_to (void *closure,
     stroker->current_face.cw.x += dev_slope.dx;
     stroker->current_face.cw.y += dev_slope.dy;
 
-    contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);
-    contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);
+    if (move_last) {
+	*_cairo_contour_last_point (&stroker->cw.contour) = stroker->current_face.cw;
+	*_cairo_contour_last_point (&stroker->ccw.contour) = stroker->current_face.ccw;
+    } else {
+	contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);
+	contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);
+    }
 
     return CAIRO_STATUS_SUCCESS;
 }
@@ -1187,6 +1201,37 @@ spline_to (void *closure,
     } else {
 	compute_face (point, tangent, stroker, &face);
 
+	if (face.dev_slope.x * stroker->current_face.dev_slope.x +
+	    face.dev_slope.y * stroker->current_face.dev_slope.y < 0)
+	{
+	    const cairo_point_t *inpt, *outpt;
+	    struct stroke_contour *outer;
+	    int clockwise = join_is_clockwise (&stroker->current_face, &face);
+
+	    stroker->current_face.cw.x += face.point.x - stroker->current_face.point.x;
+	    stroker->current_face.cw.y += face.point.y - stroker->current_face.point.y;
+	    contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);
+
+	    stroker->current_face.ccw.x += face.point.x - stroker->current_face.point.x;
+	    stroker->current_face.ccw.y += face.point.y - stroker->current_face.point.y;
+	    contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);
+
+	    if (clockwise) {
+		inpt = &stroker->current_face.cw;
+		outpt = &face.cw;
+		outer = &stroker->cw;
+	    } else {
+		inpt = &stroker->current_face.ccw;
+		outpt = &face.ccw;
+		outer = &stroker->ccw;
+	    }
+	    add_fan (stroker,
+		     &stroker->current_face.dev_vector,
+		     &face.dev_vector,
+		     &stroker->current_face.point, inpt, outpt,
+		     clockwise, outer);
+	}
+
 	contour_add_point (stroker, &stroker->cw, &face.cw);
 	contour_add_point (stroker, &stroker->ccw, &face.ccw);
     }
@@ -1328,6 +1373,8 @@ _cairo_path_fixed_stroke_to_polygon (const cairo_path_fixed_t	*path,
     stroker.has_initial_sub_path = FALSE;
 
 #if DEBUG
+    remove ("contours.txt");
+    remove ("polygons.txt");
     _cairo_contour_init (&stroker.path, 0);
 #endif
     _cairo_contour_init (&stroker.cw.contour, 1);