ref: 432efa25b3476a6884426c0a30f6d6a624310e5d
parent: db4083fd7f19fd3fbd5d5a8e60d5c8e0f19778bd
author: Alexei Podtelezhnikov <apodtele@gmail.com>
date: Wed Sep 25 17:50:16 EDT 2019
* src/base/ftstroke.c (ft_stroker_outside): Speed up clipped miter. * include/freetype/ftstroke.h: Wordsmith miter docs.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-09-25 Alexei Podtelezhnikov <apodtele@gmail.com>
+
+ * src/base/ftstroke.c (ft_stroker_outside): Speed up clipped miter.
+ * include/freetype/ftstroke.h: Wordsmith miter docs.
+
2019-09-25 Werner Lemberg <wl@gnu.org>
* src/sfnt/sfwoff2.c (woff2_open_font): Check (sum of) table sizes.
--- a/include/freetype/ftstroke.h
+++ b/include/freetype/ftstroke.h
@@ -114,22 +114,19 @@
* FT_STROKER_LINEJOIN_MITER_FIXED ::
* Used to render mitered line joins, with fixed bevels if the miter
* limit is exceeded. The outer edges of the strokes for the two
- * segments are extended until they meet at an angle. If the segments
- * meet at too sharp an angle (such that the miter would extend from
- * the intersection of the segments a distance greater than the product
- * of the miter limit value and the border radius), then a bevel join
- * (see above) is used instead. This prevents long spikes being
- * created. `FT_STROKER_LINEJOIN_MITER_FIXED` generates a miter line
- * join as used in PostScript and PDF.
+ * segments are extended until they meet at an angle. A bevel join
+ * (see above) is used if the segments meet at too sharp an angle and
+ * the outer edges meet beyond a distance corresponding to the meter
+ * limit. This prevents long spikes being created.
+ * `FT_STROKER_LINEJOIN_MITER_FIXED` generates a miter line join as
+ * used in PostScript and PDF.
*
* FT_STROKER_LINEJOIN_MITER_VARIABLE ::
* FT_STROKER_LINEJOIN_MITER ::
* Used to render mitered line joins, with variable bevels if the miter
- * limit is exceeded. The intersection of the strokes is clipped at a
- * line perpendicular to the bisector of the angle between the strokes,
- * at the distance from the intersection of the segments equal to the
- * product of the miter limit value and the border radius. This
- * prevents long spikes being created.
+ * limit is exceeded. The intersection of the strokes is clipped
+ * perpendicularly to the bisector, at a distance corresponding to
+ * the miter limit. This prevents long spikes being created.
* `FT_STROKER_LINEJOIN_MITER_VARIABLE` generates a mitered line join
* as used in XPS. `FT_STROKER_LINEJOIN_MITER` is an alias for
* `FT_STROKER_LINEJOIN_MITER_VARIABLE`, retained for backward
@@ -296,12 +293,16 @@
* The line join style.
*
* miter_limit ::
- * The miter limit for the `FT_STROKER_LINEJOIN_MITER_FIXED` and
- * `FT_STROKER_LINEJOIN_MITER_VARIABLE` line join styles, expressed as
- * 16.16 fixed-point value.
+ * The maximum reciprocal sine of half-angle at the miter join,
+ * expressed as 16.16 fixed point value.
*
* @note:
* The radius is expressed in the same units as the outline coordinates.
+ *
+ * The miter limit multiplied by the radius gives the maximum size
+ * of a miter spike, at which it is clipped for
+ * `FT_STROKER_LINEJOIN_MITER_VARIABLE` or replaced with a bevel join for
+ * `FT_STROKER_LINEJOIN_MITER_FIXED`.
*
* This function calls @FT_Stroker_Rewind automatically.
*/
--- a/src/base/ftstroke.c
+++ b/src/base/ftstroke.c
@@ -1062,10 +1062,10 @@
else
{/* this is a mitered (pointed) or beveled (truncated) corner */
- FT_Fixed sigma = 0, radius = stroker->radius;
- FT_Angle theta = 0, phi = 0;
- FT_Fixed thcos = 0;
- FT_Bool bevel, fixed_bevel;
+ FT_Fixed radius = stroker->radius;
+ FT_Vector sigma;
+ FT_Angle theta = 0, phi = 0;
+ FT_Bool bevel, fixed_bevel;
rotate = FT_SIDE_TO_ROTATE( side );
@@ -1076,26 +1076,20 @@
fixed_bevel =
FT_BOOL( stroker->line_join != FT_STROKER_LINEJOIN_MITER_VARIABLE );
+ /* check miter limit first */
if ( !bevel )
{- theta = FT_Angle_Diff( stroker->angle_in, stroker->angle_out );
+ theta = FT_Angle_Diff( stroker->angle_in, stroker->angle_out ) / 2;
- if ( theta == FT_ANGLE_PI )
- {- theta = rotate;
- phi = stroker->angle_in;
- }
- else
- {- theta /= 2;
- phi = stroker->angle_in + theta + rotate;
- }
+ if ( theta == FT_ANGLE_PI2 )
+ theta = -rotate;
- thcos = FT_Cos( theta );
- sigma = FT_MulFix( stroker->miter_limit, thcos );
+ phi = stroker->angle_in + theta + rotate;
+ FT_Vector_From_Polar( &sigma, stroker->miter_limit, theta );
+
/* is miter limit exceeded? */
- if ( sigma < 0x10000L )
+ if ( sigma.x < 0x10000L )
{/* don't create variable bevels for very small deviations; */
/* FT_Sin(x) = 0 for x <= 57 */
@@ -1122,36 +1116,34 @@
border->movable = FALSE;
error = ft_stroke_border_lineto( border, &delta, FALSE );
}
- else /* variable bevel */
+ else /* variable bevel or clipped miter */
{/* the miter is truncated */
FT_Vector middle, delta;
- FT_Fixed length;
+ FT_Fixed coef;
- /* compute middle point */
+ /* compute middle point and first angle point */
FT_Vector_From_Polar( &middle,
FT_MulFix( radius, stroker->miter_limit ),
phi );
+
+ coef = FT_DivFix( 0x10000L - sigma.x, sigma.y );
+ delta.x = FT_MulFix( middle.y, coef );
+ delta.y = FT_MulFix( -middle.x, coef );
+
middle.x += stroker->center.x;
middle.y += stroker->center.y;
+ delta.x += middle.x;
+ delta.y += middle.y;
- /* compute first angle point */
- length = FT_MulDiv( radius, 0x10000L - sigma,
- ft_pos_abs( FT_Sin( theta ) ) );
-
- FT_Vector_From_Polar( &delta, length, phi + rotate );
- delta.x += middle.x;
- delta.y += middle.y;
-
error = ft_stroke_border_lineto( border, &delta, FALSE );
if ( error )
goto Exit;
/* compute second angle point */
- FT_Vector_From_Polar( &delta, length, phi - rotate );
- delta.x += middle.x;
- delta.y += middle.y;
+ delta.x = middle.x - delta.x + middle.x;
+ delta.y = middle.y - delta.y + middle.y;
error = ft_stroke_border_lineto( border, &delta, FALSE );
if ( error )
@@ -1178,7 +1170,7 @@
FT_Vector delta;
- length = FT_DivFix( stroker->radius, thcos );
+ length = FT_MulDiv( stroker->radius, stroker->miter_limit, sigma.x );
FT_Vector_From_Polar( &delta, length, phi );
delta.x += stroker->center.x;