Remove _cairo_slope_[counter_]clockwise

These two functions were hiding away some important details
about strictness of inequalities. Also, the callers differ
on the strictness they need. Everything is cleaner and more
flexible by making the callers just call _cairo_slope_compare
directly.

1 files changed, 16 insertions, 14 deletions

diff --git a/src/cairo-pen.c b/src/cairo-pen.c
index cde129c5..fc01970f 100644
--- a/src/cairo-pen.c
+++ b/src/cairo-pen.c
@@ -302,13 +302,15 @@ _cairo_pen_compute_slopes (cairo_pen_t *pen)
 /*
  * Find active pen vertex for clockwise edge of stroke at the given slope.
  *
- * Note: The behavior of this function is sensitive to the sense of
- * the inequality within _cairo_slope_clockwise/_cairo_slope_counter_clockwise.
+ * The strictness of the inequalities here is delicate. The issue is
+ * that the slope_ccw member of one pen vertex will be equivalent to
+ * the slope_cw member of the next pen vertex in a counterclockwise
+ * order. However, for this function, we care strongly about which
+ * vertex is returned.
  *
- * The issue is that the slope_ccw member of one pen vertex will be
- * equivalent to the slope_cw member of the next pen vertex in a
- * counterclockwise order. However, for this function, we care
- * strongly about which vertex is returned.
+ * [I think the "care strongly" above has to do with ensuring that the
+ * pen's "extra points" from the spline's initial and final slopes are
+ * properly found when beginning the spline stroking.]
  */
 void
 _cairo_pen_find_active_cw_vertex_index (cairo_pen_t *pen,
@@ -318,8 +320,8 @@ _cairo_pen_find_active_cw_vertex_index (cairo_pen_t *pen,
     int i;
 
     for (i=0; i < pen->num_vertices; i++) {
-	if (_cairo_slope_clockwise (slope, &pen->vertices[i].slope_ccw)
-	    && _cairo_slope_counter_clockwise (slope, &pen->vertices[i].slope_cw))
+	if ((_cairo_slope_compare (slope, &pen->vertices[i].slope_ccw) < 0) &&
+	    (_cairo_slope_compare (slope, &pen->vertices[i].slope_cw) >= 0))
 	    break;
     }
 
@@ -336,8 +338,8 @@ _cairo_pen_find_active_cw_vertex_index (cairo_pen_t *pen,
 
 /* Find active pen vertex for counterclockwise edge of stroke at the given slope.
  *
- * Note: The behavior of this function is sensitive to the sense of
- * the inequality within _cairo_slope_clockwise/_cairo_slope_counter_clockwise.
+ * Note: See the comments for _cairo_pen_find_active_cw_vertex_index
+ * for some details about the strictness of the inequalities here.
  */
 void
 _cairo_pen_find_active_ccw_vertex_index (cairo_pen_t *pen,
@@ -352,8 +354,8 @@ _cairo_pen_find_active_ccw_vertex_index (cairo_pen_t *pen,
     slope_reverse.dy = -slope_reverse.dy;
 
     for (i=pen->num_vertices-1; i >= 0; i--) {
-	if (_cairo_slope_counter_clockwise (&pen->vertices[i].slope_ccw, &slope_reverse)
-	    && _cairo_slope_clockwise (&pen->vertices[i].slope_cw, &slope_reverse))
+	if ((_cairo_slope_compare (&pen->vertices[i].slope_ccw, &slope_reverse) >= 0) &&
+	    (_cairo_slope_compare (&pen->vertices[i].slope_cw, &slope_reverse) < 0))
 	    break;
     }
 
@@ -415,10 +417,10 @@ _cairo_pen_stroke_spline_half (cairo_pen_t *pen,
 	    slope = final_slope;
 	else
 	    _cairo_slope_init (&slope, &point[i], &point[i+step]);
-	if (_cairo_slope_counter_clockwise (&slope, &pen->vertices[active].slope_ccw)) {
+	if (_cairo_slope_compare (&slope, &pen->vertices[active].slope_ccw) >= 0) {
 	    if (++active == pen->num_vertices)
 		active = 0;
-	} else if (_cairo_slope_clockwise (&slope, &pen->vertices[active].slope_cw)) {
+	} else if (_cairo_slope_compare (&slope, &pen->vertices[active].slope_cw) < 0) {
 	    if (--active == -1)
 		active = pen->num_vertices - 1;
 	} else {