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105 lines
2.9 KiB
C
105 lines
2.9 KiB
C
#include <gdk-pixbuf/gdk-pixbuf.h>
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#include <cairo/cairo.h>
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#include "client/cairo.h"
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#ifndef GDK_PIXBUF_CHECK_VERSION
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#define GDK_PIXBUF_CHECK_VERSION(major,minor,micro) \
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(GDK_PIXBUF_MAJOR > (major) || \
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(GDK_PIXBUF_MAJOR == (major) && GDK_PIXBUF_MINOR > (minor)) || \
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(GDK_PIXBUF_MAJOR == (major) && GDK_PIXBUF_MINOR == (minor) && \
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GDK_PIXBUF_MICRO >= (micro)))
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#endif
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cairo_surface_t* gdk_cairo_image_surface_create_from_pixbuf(const GdkPixbuf *gdkbuf) {
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int chan = gdk_pixbuf_get_n_channels(gdkbuf);
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if (chan < 3) return NULL;
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#if GDK_PIXBUF_CHECK_VERSION(2,32,0)
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const guint8* gdkpix = gdk_pixbuf_read_pixels(gdkbuf);
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#else
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const guint8* gdkpix = gdk_pixbuf_get_pixels(gdkbuf);
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#endif
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if (!gdkpix) {
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return NULL;
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}
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gint w = gdk_pixbuf_get_width(gdkbuf);
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gint h = gdk_pixbuf_get_height(gdkbuf);
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int stride = gdk_pixbuf_get_rowstride(gdkbuf);
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cairo_format_t fmt = (chan == 3) ? CAIRO_FORMAT_RGB24 : CAIRO_FORMAT_ARGB32;
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cairo_surface_t * cs = cairo_image_surface_create (fmt, w, h);
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cairo_surface_flush (cs);
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if ( !cs || cairo_surface_status(cs) != CAIRO_STATUS_SUCCESS) {
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return NULL;
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}
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int cstride = cairo_image_surface_get_stride(cs);
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unsigned char * cpix = cairo_image_surface_get_data(cs);
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if (chan == 3) {
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int i;
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for (i = h; i; --i) {
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const guint8 *gp = gdkpix;
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unsigned char *cp = cpix;
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const guint8* end = gp + 3*w;
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while (gp < end) {
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#if G_BYTE_ORDER == G_LITTLE_ENDIAN
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cp[0] = gp[2];
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cp[1] = gp[1];
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cp[2] = gp[0];
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#else
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cp[1] = gp[0];
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cp[2] = gp[1];
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cp[3] = gp[2];
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#endif
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gp += 3;
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cp += 4;
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}
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gdkpix += stride;
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cpix += cstride;
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}
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} else {
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/* premul-color = alpha/255 * color/255 * 255 = (alpha*color)/255
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* (z/255) = z/256 * 256/255 = z/256 (1 + 1/255)
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* = z/256 + (z/256)/255 = (z + z/255)/256
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* # recurse once
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* = (z + (z + z/255)/256)/256
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* = (z + z/256 + z/256/255) / 256
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* # only use 16bit uint operations, loose some precision,
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* # result is floored.
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* -> (z + z>>8)>>8
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* # add 0x80/255 = 0.5 to convert floor to round
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* => (z+0x80 + (z+0x80)>>8 ) >> 8
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* ------
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* tested as equal to lround(z/255.0) for uint z in [0..0xfe02]
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*/
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#define PREMUL_ALPHA(x,a,b,z) G_STMT_START { z = a * b + 0x80; x = (z + (z >> 8)) >> 8; } G_STMT_END
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int i;
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for (i = h; i; --i) {
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const guint8 *gp = gdkpix;
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unsigned char *cp = cpix;
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const guint8* end = gp + 4*w;
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guint z1, z2, z3;
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while (gp < end) {
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#if G_BYTE_ORDER == G_LITTLE_ENDIAN
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PREMUL_ALPHA(cp[0], gp[2], gp[3], z1);
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PREMUL_ALPHA(cp[1], gp[1], gp[3], z2);
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PREMUL_ALPHA(cp[2], gp[0], gp[3], z3);
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cp[3] = gp[3];
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#else
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PREMUL_ALPHA(cp[1], gp[0], gp[3], z1);
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PREMUL_ALPHA(cp[2], gp[1], gp[3], z2);
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PREMUL_ALPHA(cp[3], gp[2], gp[3], z3);
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cp[0] = gp[3];
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#endif
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gp += 4;
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cp += 4;
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}
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gdkpix += stride;
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cpix += cstride;
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}
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#undef PREMUL_ALPHA
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}
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cairo_surface_mark_dirty(cs);
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return cs;
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}
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