File: cairo.c

package info (click to toggle)
swaybg 1.0-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, sid
  • size: 152 kB
  • sloc: ansic: 947; xml: 240; makefile: 6
file content (126 lines) | stat: -rw-r--r-- 3,453 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
#include <stdint.h>
#include <cairo/cairo.h>
#include "cairo.h"
#if HAVE_GDK_PIXBUF
#include <gdk-pixbuf/gdk-pixbuf.h>
#endif

void cairo_set_source_u32(cairo_t *cairo, uint32_t color) {
	cairo_set_source_rgba(cairo,
			(color >> (3*8) & 0xFF) / 255.0,
			(color >> (2*8) & 0xFF) / 255.0,
			(color >> (1*8) & 0xFF) / 255.0,
			(color >> (0*8) & 0xFF) / 255.0);
}

cairo_subpixel_order_t to_cairo_subpixel_order(enum wl_output_subpixel subpixel) {
	switch (subpixel) {
	case WL_OUTPUT_SUBPIXEL_HORIZONTAL_RGB:
		return CAIRO_SUBPIXEL_ORDER_RGB;
	case WL_OUTPUT_SUBPIXEL_HORIZONTAL_BGR:
		return CAIRO_SUBPIXEL_ORDER_BGR;
	case WL_OUTPUT_SUBPIXEL_VERTICAL_RGB:
		return CAIRO_SUBPIXEL_ORDER_VRGB;
	case WL_OUTPUT_SUBPIXEL_VERTICAL_BGR:
		return CAIRO_SUBPIXEL_ORDER_VBGR;
	default:
		return CAIRO_SUBPIXEL_ORDER_DEFAULT;
	}
	return CAIRO_SUBPIXEL_ORDER_DEFAULT;
}

#if HAVE_GDK_PIXBUF
cairo_surface_t* gdk_cairo_image_surface_create_from_pixbuf(const GdkPixbuf *gdkbuf) {
	int chan = gdk_pixbuf_get_n_channels(gdkbuf);
	if (chan < 3) {
		return NULL;
	}

	const guint8* gdkpix = gdk_pixbuf_read_pixels(gdkbuf);
	if (!gdkpix) {
		return NULL;
	}
	gint w = gdk_pixbuf_get_width(gdkbuf);
	gint h = gdk_pixbuf_get_height(gdkbuf);
	int stride = gdk_pixbuf_get_rowstride(gdkbuf);

	cairo_format_t fmt = (chan == 3) ? CAIRO_FORMAT_RGB24 : CAIRO_FORMAT_ARGB32;
	cairo_surface_t * cs = cairo_image_surface_create (fmt, w, h);
	cairo_surface_flush (cs);
	if ( !cs || cairo_surface_status(cs) != CAIRO_STATUS_SUCCESS) {
		return NULL;
	}

	int cstride = cairo_image_surface_get_stride(cs);
	unsigned char * cpix = cairo_image_surface_get_data(cs);

	if (chan == 3) {
		int i;
		for (i = h; i; --i) {
			const guint8 *gp = gdkpix;
			unsigned char *cp = cpix;
			const guint8* end = gp + 3*w;
			while (gp < end) {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
				cp[0] = gp[2];
				cp[1] = gp[1];
				cp[2] = gp[0];
#else
				cp[1] = gp[0];
				cp[2] = gp[1];
				cp[3] = gp[2];
#endif
				gp += 3;
				cp += 4;
			}
			gdkpix += stride;
			cpix += cstride;
		}
	} else {
		/* premul-color = alpha/255 * color/255 * 255 = (alpha*color)/255
		 * (z/255) = z/256 * 256/255     = z/256 (1 + 1/255)
		 *         = z/256 + (z/256)/255 = (z + z/255)/256
		 *         # recurse once
		 *         = (z + (z + z/255)/256)/256
		 *         = (z + z/256 + z/256/255) / 256
		 *         # only use 16bit uint operations, loose some precision,
		 *         # result is floored.
		 *       ->  (z + z>>8)>>8
		 *         # add 0x80/255 = 0.5 to convert floor to round
		 *       =>  (z+0x80 + (z+0x80)>>8 ) >> 8
		 * ------
		 * tested as equal to lround(z/255.0) for uint z in [0..0xfe02]
		 */
#define PREMUL_ALPHA(x,a,b,z) \
		G_STMT_START { z = a * b + 0x80; x = (z + (z >> 8)) >> 8; } \
		G_STMT_END
		int i;
		for (i = h; i; --i) {
			const guint8 *gp = gdkpix;
			unsigned char *cp = cpix;
			const guint8* end = gp + 4*w;
			guint z1, z2, z3;
			while (gp < end) {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
				PREMUL_ALPHA(cp[0], gp[2], gp[3], z1);
				PREMUL_ALPHA(cp[1], gp[1], gp[3], z2);
				PREMUL_ALPHA(cp[2], gp[0], gp[3], z3);
				cp[3] = gp[3];
#else
				PREMUL_ALPHA(cp[1], gp[0], gp[3], z1);
				PREMUL_ALPHA(cp[2], gp[1], gp[3], z2);
				PREMUL_ALPHA(cp[3], gp[2], gp[3], z3);
				cp[0] = gp[3];
#endif
				gp += 4;
				cp += 4;
			}
			gdkpix += stride;
			cpix += cstride;
		}
#undef PREMUL_ALPHA
	}
	cairo_surface_mark_dirty(cs);
	return cs;
}
#endif // HAVE_GDK_PIXBUF