diff options
Diffstat (limited to 'common/background-image.c')
| -rw-r--r-- | common/background-image.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/common/background-image.c b/common/background-image.c index 4431b725..de42e8e9 100644 --- a/common/background-image.c +++ b/common/background-image.c @@ -2,6 +2,9 @@ #include "background-image.h" #include "cairo.h" #include "log.h" +#if HAVE_GDK_PIXBUF +#include <gdk-pixbuf/gdk-pixbuf.h> +#endif enum background_mode parse_background_mode(const char *mode) { if (strcmp(mode, "stretch") == 0) { @@ -21,6 +24,103 @@ enum background_mode parse_background_mode(const char *mode) { return BACKGROUND_MODE_INVALID; } +#if HAVE_GDK_PIXBUF +static 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 + cairo_surface_t *load_background_image(const char *path) { cairo_surface_t *image; #if HAVE_GDK_PIXBUF |