[Commit] cairo/src cairo_path_stroke.c,1.5,1.6 cairo_pen.c,1.5,1.6
Keith Packard
commit at keithp.com
Fri Sep 5 14:25:49 PDT 2003
Committed by: keithp
Update of /local/src/CVS/cairo/src
In directory home.keithp.com:/tmp/cvs-serv32385/src
Modified Files:
cairo_path_stroke.c cairo_pen.c
Log Message:
* src/cairo_path_stroke.c: comment face computations, check for
reflecting transformation to select correct face orientations
* src/cairo_pen.c: check for reflecting transform when computing
pen to ensure consistent pen orientation
Index: cairo_path_stroke.c
===================================================================
RCS file: /local/src/CVS/cairo/src/cairo_path_stroke.c,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -d -r1.5 -r1.6
--- cairo_path_stroke.c 4 Sep 2003 18:54:09 -0000 1.5
+++ cairo_path_stroke.c 5 Sep 2003 20:25:47 -0000 1.6
@@ -171,26 +171,22 @@
case CAIRO_LINE_JOIN_ROUND: {
int i;
int start, step, stop;
- cairo_point_t tri[3], initial, final;
+ cairo_point_t tri[3];
cairo_pen_t *pen = &gstate->pen_regular;
tri[0] = in->pt;
if (clockwise) {
- initial = in->ccw;
_cairo_pen_find_active_ccw_vertex_index (pen, &in->dev_vector, &start);
step = -1;
_cairo_pen_find_active_ccw_vertex_index (pen, &out->dev_vector, &stop);
- final = out->ccw;
} else {
- initial = in->cw;
_cairo_pen_find_active_cw_vertex_index (pen, &in->dev_vector, &start);
step = +1;
_cairo_pen_find_active_cw_vertex_index (pen, &out->dev_vector, &stop);
- final = out->cw;
}
i = start;
- tri[1] = initial;
+ tri[1] = *inpt;
while (i != stop) {
tri[2] = in->pt;
_translate_point (&tri[2], &pen->vertex[i].pt);
@@ -203,7 +199,7 @@
i = 0;
}
- tri[2] = final;
+ tri[2] = *outpt;
return _cairo_traps_tessellate_triangle (stroker->traps, tri);
}
@@ -388,36 +384,55 @@
static void
_compute_face (cairo_point_t *pt, cairo_slope_t *slope, cairo_gstate_t *gstate, cairo_stroke_face_t *face)
{
- double mag, tmp;
- double dx, dy;
+ double mag, det;
+ double line_dx, line_dy;
+ double face_dx, face_dy;
XPointDouble usr_vector;
cairo_point_t offset_ccw, offset_cw;
- dx = cairo_fixed_to_double (slope->dx);
- dy = cairo_fixed_to_double (slope->dy);
+ line_dx = cairo_fixed_to_double (slope->dx);
+ line_dy = cairo_fixed_to_double (slope->dy);
- cairo_matrix_transform_distance (&gstate->ctm_inverse, &dx, &dy);
+ /* faces are normal in user space, not device space */
+ cairo_matrix_transform_distance (&gstate->ctm_inverse, &line_dx, &line_dy);
- mag = sqrt (dx * dx + dy * dy);
+ mag = sqrt (line_dx * line_dx + line_dy * line_dy);
if (mag == 0) {
/* XXX: Can't compute other face points. Do we want a tag in the face for this case? */
return;
}
- dx /= mag;
- dy /= mag;
+ /* normalize to unit length */
+ line_dx /= mag;
+ line_dy /= mag;
- usr_vector.x = dx;
- usr_vector.y = dy;
+ usr_vector.x = line_dx;
+ usr_vector.y = line_dy;
- tmp = dx;
- dx = - dy * (gstate->line_width / 2.0);
- dy = tmp * (gstate->line_width / 2.0);
+ /*
+ * rotate to get a line_width/2 vector along the face, note that
+ * the vector must be rotated the right direction in device space,
+ * but by 90° in user space. So, the rotation depends on
+ * whether the ctm reflects or not, and that can be determined
+ * by looking at the determinant of the matrix.
+ */
+ _cairo_matrix_compute_determinant (&gstate->ctm, &det);
+ if (det >= 0)
+ {
+ face_dx = - line_dy * (gstate->line_width / 2.0);
+ face_dy = line_dx * (gstate->line_width / 2.0);
+ }
+ else
+ {
+ face_dx = line_dy * (gstate->line_width / 2.0);
+ face_dy = - line_dx * (gstate->line_width / 2.0);
+ }
- cairo_matrix_transform_distance (&gstate->ctm, &dx, &dy);
+ /* back to device space */
+ cairo_matrix_transform_distance (&gstate->ctm, &face_dx, &face_dy);
- offset_ccw.x = cairo_double_to_fixed (dx);
- offset_ccw.y = cairo_double_to_fixed (dy);
+ offset_ccw.x = cairo_double_to_fixed (face_dx);
+ offset_ccw.y = cairo_double_to_fixed (face_dy);
offset_cw.x = -offset_ccw.x;
offset_cw.y = -offset_ccw.y;
Index: cairo_pen.c
===================================================================
RCS file: /local/src/CVS/cairo/src/cairo_pen.c,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -d -r1.5 -r1.6
--- cairo_pen.c 26 Aug 2003 14:40:17 -0000 1.5
+++ cairo_pen.c 5 Sep 2003 20:25:47 -0000 1.6
@@ -28,7 +28,7 @@
#include "cairoint.h"
static int
-_cairo_pen_vertices_needed (double radius, double tolerance, cairo_matrix_t *matrix);
+_cairo_pen_vertices_needed (double radius, double tolerance, double expansion);
static void
_cairo_pen_compute_slopes (cairo_pen_t *pen);
@@ -54,6 +54,8 @@
_cairo_pen_init (cairo_pen_t *pen, double radius, cairo_gstate_t *gstate)
{
int i;
+ int reflect;
+ double det, expansion;
if (pen->num_vertices) {
/* XXX: It would be nice to notice that the pen is already properly constructed.
@@ -68,7 +70,20 @@
pen->radius = radius;
pen->tolerance = gstate->tolerance;
- pen->num_vertices = _cairo_pen_vertices_needed (radius, gstate->tolerance, &gstate->ctm);
+ /* The determinant represents the area expansion factor of the
+ transform. In the worst case, this is entirely in one
+ dimension, which is what we assume here. */
+
+ _cairo_matrix_compute_determinant (&gstate->ctm, &det);
+ if (det >= 0) {
+ reflect = 0;
+ expansion = det;
+ } else {
+ reflect = 1;
+ expansion = -det;
+ }
+
+ pen->num_vertices = _cairo_pen_vertices_needed (radius, gstate->tolerance, expansion);
/* number of vertices must be even */
if (pen->num_vertices % 2)
pen->num_vertices++;
@@ -78,14 +93,20 @@
return CAIRO_STATUS_NO_MEMORY;
}
+ /*
+ * Compute pen coordinates. To generate the right ellipse, compute points around
+ * a circle in user space and transform them to device space. To get a consistent
+ * orientation in device space, flip the pen if the transformation matrix
+ * is reflecting
+ */
for (i=0; i < pen->num_vertices; i++) {
double theta = 2 * M_PI * i / (double) pen->num_vertices;
- double dx = radius * cos (theta);
- double dy = radius * sin (theta);
+ double dx = radius * cos (reflect ? -theta : theta);
+ double dy = radius * sin (reflect ? -theta : theta);
cairo_pen_vertex_t *v = &pen->vertex[i];
cairo_matrix_transform_distance (&gstate->ctm, &dx, &dy);
- v->pt.x = XDoubleToFixed (dx);
- v->pt.y = XDoubleToFixed (dy);
+ v->pt.x = cairo_double_to_fixed (dx);
+ v->pt.y = cairo_double_to_fixed (dy);
}
_cairo_pen_compute_slopes (pen);
@@ -157,15 +178,9 @@
}
static int
-_cairo_pen_vertices_needed (double radius, double tolerance, cairo_matrix_t *matrix)
+_cairo_pen_vertices_needed (double radius, double tolerance, double expansion)
{
- double expansion, theta;
-
- /* The determinant represents the area expansion factor of the
- transform. In the worst case, this is entirely in one
- dimension, which is what we assume here. */
-
- _cairo_matrix_compute_determinant (matrix, &expansion);
+ double theta;
if (tolerance > expansion*radius) {
return 4;
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