Attachment 106672 Details for Bug 84115 – Eliminate precision loss when emitting spline joins

[patch] Eliminate precision loss when emitting spline joins

0001-stroke-traps-Emit-join-without-loss-of-precision.patch (text/plain), 4.22 KB, created by Chris Wilson on 2014-09-22 12:00:21 UTC

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Creator: Chris Wilson

Created: 2014-09-22 12:00:21 UTC

Size: 4.22 KB

patch

obsolete

>From 36eabcbb9abee463a33b365387eeefd7e8806d24 Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Mon, 22 Sep 2014 12:53:08 +0100
>Subject: [PATCH] stroke,traps: Emit join without loss of precision
>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84115
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> src/cairo-path-stroke-traps.c | 18 +++++++++--
> src/cairo-traps-private.h     |  5 +++
> src/cairo-traps.c             | 72 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 92 insertions(+), 3 deletions(-)
>
>diff --git a/src/cairo-path-stroke-traps.c b/src/cairo-path-stroke-traps.c
>index 304dea7..c2e290c 100644
>--- a/src/cairo-path-stroke-traps.c
>+++ b/src/cairo-path-stroke-traps.c
>@@ -929,15 +929,27 @@ spline_to (void *closure,
> 
> 	join (stroker, &stroker->current_face, &face);
>     } else {
>-	cairo_point_t rectangle[4];
>+	cairo_point_t rectangle[4], triangle[3];
> 
> 	compute_face (&stroker->current_face.point, tangent, stroker, &face);
> 
>-	join (stroker, &stroker->current_face, &face);
>-
> 	rectangle[0] = face.cw;
> 	rectangle[1] = face.ccw;
> 
>+	rectangle[2] = stroker->current_face.cw;
>+	rectangle[3] = stroker->current_face.ccw;
>+
>+	triangle[0] = face.point;
>+	if (join_is_clockwise (&face, &stroker->current_face)) {
>+		triangle[1] = rectangle[1];
>+		triangle[2] = rectangle[3];
>+	} else {
>+		triangle[1] = rectangle[0];
>+		triangle[2] = rectangle[2];
>+	}
>+	_cairo_traps_tessellate_triangle_with_edges (stroker->traps,
>+						     triangle, rectangle);
>+
> 	rectangle[2].x = point->x - face.point.x;
> 	rectangle[2].y = point->y - face.point.y;
> 	face.point = *point;
>diff --git a/src/cairo-traps-private.h b/src/cairo-traps-private.h
>index 7fef062..196d33e 100644
>--- a/src/cairo-traps-private.h
>+++ b/src/cairo-traps-private.h
>@@ -95,6 +95,11 @@ _cairo_traps_tessellate_triangle (cairo_traps_t *traps,
> 				  const cairo_point_t t[3]);
> 
> cairo_private void
>+_cairo_traps_tessellate_triangle_with_edges (cairo_traps_t *traps,
>+					     const cairo_point_t t[3],
>+					     const cairo_point_t edges[4]);
>+
>+cairo_private void
> _cairo_traps_tessellate_convex_quad (cairo_traps_t *traps,
> 				     const cairo_point_t q[4]);
> 
>diff --git a/src/cairo-traps.c b/src/cairo-traps.c
>index 9f1d4a7..cea96d5 100644
>--- a/src/cairo-traps.c
>+++ b/src/cairo-traps.c
>@@ -403,6 +403,78 @@ _cairo_traps_tessellate_triangle (cairo_traps_t *traps,
>     _cairo_traps_tessellate_convex_quad (traps, quad);
> }
> 
>+static void add_tri (cairo_traps_t *traps,
>+		     int y1, int y2,
>+		     cairo_line_t *left,
>+		     cairo_line_t *right)
>+{
>+    cairo_slope_t a, b;
>+
>+    if (y2 < y1) {
>+	int tmp = y1;
>+	y1 = y2;
>+	y2 = tmp;
>+    }
>+
>+    _cairo_slope_init (&a, &left->p1, &left->p2);
>+    _cairo_slope_init (&b, &right->p1, &right->p2);
>+
>+    if (_cairo_slope_compare (&a, &b) < 0) {
>+	cairo_line_t *tmp = left;
>+	left = right;
>+	right = tmp;
>+    }
>+
>+    _cairo_traps_add_clipped_trap (traps, y1, y2, left, right);
>+}
>+
>+void
>+_cairo_traps_tessellate_triangle_with_edges (cairo_traps_t *traps,
>+					     const cairo_point_t t[3],
>+					     const cairo_point_t edges[4])
>+{
>+    cairo_line_t lines[3];
>+
>+    if (edges[0].y <= edges[1].y) {
>+	    lines[0].p1 = edges[0];
>+	    lines[0].p2 = edges[1];
>+    } else {
>+	    lines[0].p1 = edges[1];
>+	    lines[0].p2 = edges[0];
>+    }
>+
>+    if (edges[2].y <= edges[3].y) {
>+	    lines[1].p1 = edges[2];
>+	    lines[1].p2 = edges[3];
>+    } else {
>+	    lines[1].p1 = edges[3];
>+	    lines[1].p2 = edges[2];
>+    }
>+
>+    if (t[1].y == t[2].y) {
>+	add_tri (traps, t[0].y, t[1].y, &lines[0], &lines[1]);
>+	return;
>+    }
>+
>+    if (t[1].y <= t[2].y) {
>+	    lines[2].p1 = t[1];
>+	    lines[2].p2 = t[2];
>+    } else {
>+	    lines[2].p1 = t[2];
>+	    lines[2].p2 = t[1];
>+    }
>+
>+    if (((t[1].y - t[0].y) < 0) ^ ((t[2].y - t[0].y) < 0)) {
>+	add_tri (traps, t[0].y, t[1].y, &lines[0], &lines[2]);
>+	add_tri (traps, t[0].y, t[2].y, &lines[1], &lines[2]);
>+    } else if (abs(t[1].y - t[0].y) < abs(t[2].y - t[0].y)) {
>+	add_tri (traps, t[0].y, t[1].y, &lines[0], &lines[1]);
>+	add_tri (traps, t[1].y, t[2].y, &lines[2], &lines[1]);
>+    } else {
>+	add_tri (traps, t[0].y, t[2].y, &lines[1], &lines[0]);
>+	add_tri (traps, t[1].y, t[2].y, &lines[2], &lines[0]);
>+    }
>+}
> 
> /**
>  * _cairo_traps_init_boxes:
>-- 
>1.9.3
>

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Attachments on bug 84115: 106572 | 106672 | 106708

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