Attachment 2984 Details for Bug 4188 – change cairo_arc_to to use the major axis calculation.

[patch] change cairo_arc_to to use the major axis calculation.

cairo-arc-to-use-major-axis.diff (text/plain), 1.27 KB, created by Bertram Felgenhauer on 2005-08-22 11:22:54 UTC

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Creator: Bertram Felgenhauer

Created: 2005-08-22 11:22:54 UTC

Size: 1.27 KB

patch

obsolete

>Index: src/cairo-arc.c
>===================================================================
>RCS file: /cvs/cairo/cairo/src/cairo-arc.c,v
>retrieving revision 1.4
>diff -u -r1.4 cairo-arc.c
>--- src/cairo-arc.c	5 Aug 2005 17:05:29 -0000	1.4
>+++ src/cairo-arc.c	22 Aug 2005 17:56:15 -0000
>@@ -100,27 +100,19 @@
>     return angle;
> }
> 
>-/* XXX: The computation here if bogus. Correct math (with proof!) is
>- * available in _cairo_pen_vertices_needed. */
> static int
> _arc_segments_needed (double	      angle,
> 		      double	      radius,
> 		      cairo_matrix_t *ctm,
> 		      double	      tolerance)
> {
>-    double l1, l2, lmax;
>-    double max_angle;
>+    double major_axis, max_angle;
> 
>-    _cairo_matrix_compute_eigen_values (ctm, &l1, &l2);
>-
>-    l1 = fabs (l1);
>-    l2 = fabs (l2);
>-    if (l1 > l2)
>-	lmax = l1;
>-    else
>-	lmax = l2;
>-
>-    max_angle = _arc_max_angle_for_tolerance_normalized (tolerance / (radius * lmax));
>+    /* the error is amplified by at most the length of the
>+     * major axis of the circle; see cairo-pen.c for a more detailed analysis
>+     * of this. */
>+    major_axis = _cairo_matrix_transformed_circle_major_axis (ctm, radius);
>+    max_angle = _arc_max_angle_for_tolerance_normalized (tolerance / major_axis);
> 
>     return (int) ceil (angle / max_angle);
> }

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Attachments on bug 4188: 2983 | 2984 | 2985 | 2996

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