labwc/src/common/graphic-helpers.c

115 lines
2.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
#include "common/graphic-helpers.h"
#include <cairo.h>
#include <glib.h> /* g_ascii_strcasecmp */
#include <wlr/util/box.h>
#include "common/macros.h"
#include "xcolor-table.h"
/* Draws a border with a specified line width */
void
draw_cairo_border(cairo_t *cairo, struct wlr_fbox fbox, double line_width)
{
cairo_save(cairo);
/* The anchor point of a line is in the center */
fbox.x += line_width / 2.0;
fbox.y += line_width / 2.0;
fbox.width -= line_width;
fbox.height -= line_width;
cairo_set_line_width(cairo, line_width);
cairo_rectangle(cairo, fbox.x, fbox.y, fbox.width, fbox.height);
cairo_stroke(cairo);
cairo_restore(cairo);
}
/* Sets the cairo color. Splits the single color channels */
void
set_cairo_color(cairo_t *cairo, const float *color)
{
/*
* We are dealing with pre-multiplied colors
* but cairo expects unmultiplied colors here
*/
float alpha = color[3];
if (alpha == 0.0f) {
cairo_set_source_rgba(cairo, 0, 0, 0, 0);
return;
}
cairo_set_source_rgba(cairo, color[0] / alpha, color[1] / alpha,
color[2] / alpha, alpha);
}
cairo_pattern_t *
color_to_pattern(const float *color)
{
float alpha = color[3];
if (alpha == 0.0f) {
return cairo_pattern_create_rgba(0, 0, 0, 0);
}
return cairo_pattern_create_rgba(color[0] / alpha, color[1] / alpha,
color[2] / alpha, alpha);
}
/*
* This is used as an optimization in font rendering and errs on the
* side of returning false (not opaque) for unknown pattern types.
*
* The 0.999 alpha threshold was chosen to be greater than 254/255
* (about 0.996) while leaving some margin for rounding errors.
*/
bool
is_pattern_opaque(cairo_pattern_t *pattern)
{
double alpha = 0;
int stops = 0;
/* solid color? */
if (cairo_pattern_get_rgba(pattern, NULL, NULL, NULL, &alpha)
== CAIRO_STATUS_SUCCESS) {
return (alpha >= 0.999);
}
/* gradient? */
if (cairo_pattern_get_color_stop_count(pattern, &stops)
== CAIRO_STATUS_SUCCESS) {
for (int s = 0; s < stops; s++) {
cairo_pattern_get_color_stop_rgba(pattern, s,
NULL, NULL, NULL, NULL, &alpha);
if (alpha < 0.999) {
return false;
}
}
return true;
}
return false; /* unknown pattern type */
}
static int
compare_xcolor_entry(const void *a, const void *b)
{
/* using ASCII version to avoid locale-dependent ordering */
return g_ascii_strcasecmp((const char *)a,
color_names + ((const struct xcolor_entry *)b)->name_offset);
}
bool
lookup_named_color(const char *name, uint32_t *argb)
{
struct xcolor_entry *found = bsearch(name, xcolors, ARRAY_SIZE(xcolors),
sizeof(struct xcolor_entry), compare_xcolor_entry);
if (!found) {
return false;
}
*argb = 0xFF000000u | ((uint32_t)found->red << 16)
| ((uint32_t)found->green << 8) | found->blue;
return true;
}