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win32-printing: fix stroke rounding problems

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The win32 CTM is changed to user space to set the stroke parameters.
As win32 uses integers for stroke parameters this will cause rounding
problems depending on the CTM used.

This is fixed by factoring out a scale from the user space CTM so that
xx, xy, yx, and yy in the CTM are all < 1. This preserves the shape
of the transformation while ensuring that the CTM does not cause
rounding problems. The stroke parameters are multiplied by the scale
value.
This commit is contained in:
Adrian Johnson 2007-10-21 23:46:52 +09:30
parent 89fe7b2ff0
commit ac9831ea55
1 changed files with 29 additions and 6 deletions
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35
src/cairo-win32-printing-surface.c
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@ -1080,14 +1080,31 @@ _cairo_win32_line_join (cairo_line_join_t join)
}
}
static void
_cairo_matrix_factor_out_scale (cairo_matrix_t *m, double *scale)
{
double s;
s = fabs (m->xx);
if (fabs (m->xy) > s)
s = fabs (m->xy);
if (fabs (m->yx) > s)
s = fabs (m->yx);
if (fabs (m->yy) > s)
s = fabs (m->yy);
*scale = s;
s = 1.0/s;
cairo_matrix_scale (m, s, s);
}
static cairo_int_status_t
_cairo_win32_printing_surface_stroke (void *abstract_surface,
cairo_operator_t op,
cairo_pattern_t *source,
cairo_path_fixed_t *path,
cairo_stroke_style_t *style,
cairo_matrix_t *ctm,
cairo_matrix_t *ctm_inverse,
cairo_matrix_t *stroke_ctm,
cairo_matrix_t *stroke_ctm_inverse,
double tolerance,
cairo_antialias_t antialias)
{
@ -1102,6 +1119,8 @@ _cairo_win32_printing_surface_stroke (void *abstract_surface,
HGDIOBJ obj;
unsigned int i;
cairo_solid_pattern_t clear;
cairo_matrix_t mat;
double scale;
if (op == CAIRO_OPERATOR_CLEAR) {
_cairo_win32_printing_surface_init_clear_color (surface, &clear);
@ -1119,18 +1138,21 @@ _cairo_win32_printing_surface_stroke (void *abstract_surface,
assert (_cairo_win32_printing_surface_operation_supported (surface, op, source));
cairo_matrix_multiply (&mat, stroke_ctm, &surface->ctm);
_cairo_matrix_factor_out_scale (&mat, &scale);
dash_array = NULL;
if (style->num_dashes) {
pen_style = PS_USERSTYLE;
dash_array = calloc (sizeof (DWORD), style->num_dashes);
for (i = 0; i < style->num_dashes; i++) {
dash_array[i] = (DWORD) style->dash[i];
dash_array[i] = (DWORD) (scale * style->dash[i]);
}
} else {
pen_style = PS_SOLID;
}
SetMiterLimit (surface->dc, (FLOAT) style->miter_limit, NULL);
SetMiterLimit (surface->dc, (FLOAT) (scale * style->miter_limit), NULL);
if (source->type == CAIRO_PATTERN_TYPE_SOLID) {
cairo_solid_pattern_t *solid = (cairo_solid_pattern_t *) source;
@ -1148,7 +1170,7 @@ _cairo_win32_printing_surface_stroke (void *abstract_surface,
_cairo_win32_line_cap (style->line_cap) |
_cairo_win32_line_join (style->line_join);
pen = ExtCreatePen(pen_style,
style->line_width < 1.0 ? 1 : _cairo_lround(style->line_width),
scale * style->line_width,
&brush,
style->num_dashes,
dash_array);
@ -1168,7 +1190,8 @@ _cairo_win32_printing_surface_stroke (void *abstract_surface,
* Switch to user space to set line parameters
*/
SaveDC (surface->dc);
_cairo_matrix_to_win32_xform (ctm, &xform);
_cairo_matrix_to_win32_xform (&mat, &xform);
xform.eDx = 0.0f;
xform.eDy = 0.0f;