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Pre-multiply gradients after color interpolation
This commit is contained in:
David Reveman
parent
f82f1ba380
commit
06ef87276e
6 changed files with 71 additions and 39 deletions
11
ChangeLog
11
ChangeLog
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@ -1,3 +1,14 @@
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2004-06-11 David Reveman <c99drn@cs.umu.se>
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* src/cairo_gstate.c (_cairo_gstate_create_pattern): Get solid color
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from color stop components.
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* src/cairoint.h: Removed cairo color from color stop.
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* src/cairo_pattern.c: Added MULTIPLY_COLORCOMP macro.
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(cairo_pattern_add_color_stop): Do not pre-multiply stop color.
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(_cairo_pattern_calc_color_at_pixel): Multiply with alpha.
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2004-05-28 Keith Packard <keithp@keithp.com>
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* configure.in:
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@ -1264,8 +1264,16 @@ _cairo_gstate_create_pattern (cairo_gstate_t *gstate,
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if (pattern->n_stops < 2) {
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pattern->type = CAIRO_PATTERN_SOLID;
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if (pattern->n_stops)
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pattern->color = pattern->stops->color;
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if (pattern->n_stops) {
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cairo_color_stop_t *stop = pattern->stops;
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_cairo_color_set_rgb (&pattern->color,
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(double) stop->color_char[0] / 0xff,
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(double) stop->color_char[1] / 0xff,
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(double) stop->color_char[2] / 0xff);
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_cairo_color_set_alpha (&pattern->color,
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(double) stop->color_char[3] / 0xff);
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}
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}
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}
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@ -27,6 +27,10 @@
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#include "cairoint.h"
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#define MULTIPLY_COLORCOMP(c1, c2) \
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((unsigned char) \
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((((unsigned char) (c1)) * (int) ((unsigned char) (c2))) / 0xff))
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void
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_cairo_pattern_init (cairo_pattern_t *pattern)
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{
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@ -247,13 +251,11 @@ cairo_pattern_add_color_stop (cairo_pattern_t *pattern,
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stop->offset = _cairo_fixed_from_double (offset);
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stop->id = pattern->n_stops;
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_cairo_color_init (&stop->color);
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_cairo_color_set_rgb (&stop->color, red, green, blue);
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_cairo_color_set_alpha (&stop->color, alpha);
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stop->color_char[0] = stop->color.red_short / 256;
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stop->color_char[1] = stop->color.green_short / 256;
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stop->color_char[2] = stop->color.blue_short / 256;
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stop->color_char[3] = stop->color.alpha_short / 256;
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stop->color_char[0] = red * 0xff;
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stop->color_char[1] = green * 0xff;
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stop->color_char[2] = blue * 0xff;
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stop->color_char[3] = alpha * 0xff;
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/* sort stops in ascending order */
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qsort (pattern->stops, pattern->n_stops, sizeof (cairo_color_stop_t),
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@ -329,16 +331,9 @@ _cairo_pattern_set_alpha (cairo_pattern_t *pattern, double alpha)
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_cairo_color_set_alpha (&pattern->color, alpha);
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for (i = 0; i < pattern->n_stops; i++) {
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cairo_color_stop_t *stop = &pattern->stops[i];
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_cairo_color_set_alpha (&stop->color, stop->color.alpha * alpha);
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stop->color_char[0] = stop->color.red_short / 256;
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stop->color_char[1] = stop->color.green_short / 256;
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stop->color_char[2] = stop->color.blue_short / 256;
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stop->color_char[3] = stop->color.alpha_short / 256;
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}
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for (i = 0; i < pattern->n_stops; i++)
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pattern->stops[i].color_char[3] =
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MULTIPLY_COLORCOMP (pattern->stops[i].color_char[3], alpha * 0xff);
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}
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void
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@ -510,6 +505,14 @@ _cairo_pattern_calc_color_at_pixel (cairo_shader_op_t *op,
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op->shader_function (op->stops[i].color_char,
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op->stops[i + 1].color_char,
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factor, pixel);
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/* multiply alpha */
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if (((unsigned char) (*pixel >> 24)) != 0xff) {
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*pixel = (*pixel & 0xff000000) |
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(MULTIPLY_COLORCOMP (*pixel >> 16, *pixel >> 24) << 16) |
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(MULTIPLY_COLORCOMP (*pixel >> 8, *pixel >> 24) << 8) |
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(MULTIPLY_COLORCOMP (*pixel >> 0, *pixel >> 24) << 0);
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}
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break;
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}
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}
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@ -1264,8 +1264,16 @@ _cairo_gstate_create_pattern (cairo_gstate_t *gstate,
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if (pattern->n_stops < 2) {
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pattern->type = CAIRO_PATTERN_SOLID;
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if (pattern->n_stops)
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pattern->color = pattern->stops->color;
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if (pattern->n_stops) {
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cairo_color_stop_t *stop = pattern->stops;
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_cairo_color_set_rgb (&pattern->color,
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(double) stop->color_char[0] / 0xff,
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(double) stop->color_char[1] / 0xff,
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(double) stop->color_char[2] / 0xff);
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_cairo_color_set_alpha (&pattern->color,
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(double) stop->color_char[3] / 0xff);
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}
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}
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}
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@ -27,6 +27,10 @@
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#include "cairoint.h"
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#define MULTIPLY_COLORCOMP(c1, c2) \
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((unsigned char) \
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((((unsigned char) (c1)) * (int) ((unsigned char) (c2))) / 0xff))
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void
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_cairo_pattern_init (cairo_pattern_t *pattern)
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{
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@ -247,13 +251,11 @@ cairo_pattern_add_color_stop (cairo_pattern_t *pattern,
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stop->offset = _cairo_fixed_from_double (offset);
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stop->id = pattern->n_stops;
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_cairo_color_init (&stop->color);
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_cairo_color_set_rgb (&stop->color, red, green, blue);
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_cairo_color_set_alpha (&stop->color, alpha);
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stop->color_char[0] = stop->color.red_short / 256;
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stop->color_char[1] = stop->color.green_short / 256;
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stop->color_char[2] = stop->color.blue_short / 256;
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stop->color_char[3] = stop->color.alpha_short / 256;
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stop->color_char[0] = red * 0xff;
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stop->color_char[1] = green * 0xff;
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stop->color_char[2] = blue * 0xff;
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stop->color_char[3] = alpha * 0xff;
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/* sort stops in ascending order */
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qsort (pattern->stops, pattern->n_stops, sizeof (cairo_color_stop_t),
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@ -329,16 +331,9 @@ _cairo_pattern_set_alpha (cairo_pattern_t *pattern, double alpha)
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_cairo_color_set_alpha (&pattern->color, alpha);
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for (i = 0; i < pattern->n_stops; i++) {
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cairo_color_stop_t *stop = &pattern->stops[i];
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_cairo_color_set_alpha (&stop->color, stop->color.alpha * alpha);
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stop->color_char[0] = stop->color.red_short / 256;
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stop->color_char[1] = stop->color.green_short / 256;
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stop->color_char[2] = stop->color.blue_short / 256;
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stop->color_char[3] = stop->color.alpha_short / 256;
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}
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for (i = 0; i < pattern->n_stops; i++)
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pattern->stops[i].color_char[3] =
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MULTIPLY_COLORCOMP (pattern->stops[i].color_char[3], alpha * 0xff);
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}
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void
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@ -510,6 +505,14 @@ _cairo_pattern_calc_color_at_pixel (cairo_shader_op_t *op,
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op->shader_function (op->stops[i].color_char,
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op->stops[i + 1].color_char,
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factor, pixel);
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/* multiply alpha */
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if (((unsigned char) (*pixel >> 24)) != 0xff) {
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*pixel = (*pixel & 0xff000000) |
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(MULTIPLY_COLORCOMP (*pixel >> 16, *pixel >> 24) << 16) |
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(MULTIPLY_COLORCOMP (*pixel >> 8, *pixel >> 24) << 8) |
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(MULTIPLY_COLORCOMP (*pixel >> 0, *pixel >> 24) << 0);
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}
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break;
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}
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}
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@ -472,7 +472,6 @@ typedef struct cairo_color_stop {
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cairo_fixed_t offset;
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cairo_fixed_48_16_t scale;
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int id;
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cairo_color_t color;
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unsigned char color_char[4];
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} cairo_color_stop_t;
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