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/*
* Description:
*
* Image scaling based on bilinear interpolation algorithm
*
* Arguments:
* @d: GdkDrawable object
* @xoff, @yoff: Background picture offset to screen
* @bgfile: Background picture filename. Alpha channel is ignored.
* @x, @y: Foregorund picture offset to background picture
* @fgfile: Foreground picture filename.
* @nx, @ny: New geometry of fgfile after scaling.
* @threshod: If foreground picture carrys alpha channel, alpha values
* exceed this threshold get displayed.
*/
static void draw_scale(
GdkDrawable* d,
int xoff, int yoff,
const char* bgfile,
int x, int y,
const char* fgfile,
int nx, int ny,
unsigned char threshold)
{
GdkPixbuf* bgbuf = gdk_pixbuf_new_from_file(bgfile, NULL);
GdkPixbuf* fgbuf = gdk_pixbuf_new_from_file(fgfile, NULL);
if(bgbuf == NULL || fgbuf == NULL)
{
g_print("Can not open %s or %s\n", bgfile, fgfile);
return;
}
int nbgchs = gdk_pixbuf_get_n_channels (bgbuf);
int nfgchs = gdk_pixbuf_get_n_channels (fgbuf);
int bgrowsz = gdk_pixbuf_get_rowstride(bgbuf);
int fgrowsz = gdk_pixbuf_get_rowstride(fgbuf);
int bgheight = gdk_pixbuf_get_height(bgbuf);
int fgheight = gdk_pixbuf_get_height(fgbuf);
int bgwidth = gdk_pixbuf_get_width(bgbuf);
int fgwidth = gdk_pixbuf_get_width(fgbuf);
#ifdef _DEBUG
g_print("bg file=%s, fg file=%s\n", bgfile, fgfile);
g_print("bg channels=%d, fg channels=%d\n", nbgchs, nfgchs);
g_print("bg row_size=%d, fg row_size=%d\n", bgrowsz, fgrowsz);
g_print("bg height=%d, fg height=%d\n", bgheight, fgheight);
g_print("bg width=%d, fg width=%d\n", bgwidth, fgwidth);
#endif
unsigned char* bp = gdk_pixbuf_get_pixels (bgbuf);
unsigned char* fp = gdk_pixbuf_get_pixels (fgbuf);
float rx = (float)fgwidth/(float)nx;
float ry = (float)fgheight/(float)ny;
int i,j, n;
for(j=0; j<ny; j++)
{
float oy = j*ry;
int iy = (int)oy;
float v = oy - iy;
for(i=0; i<nx; i++)
{
float ox = i*rx;
int ix = (int)ox;
float u = ox - ix;
int soff = (j+y)*bgrowsz+(i+x)*nbgchs;
if( (ix+1 > fgwidth) || (iy+1 > fgheight) )
{
for(n=0; n<3; n++)
bp[soff+n] = 0xff;
}
else
{
int toff = iy*fgrowsz + ix*nfgchs;
float nr = (1-u)*(1-v)*fp[toff];
float ng = (1-u)*(1-v)*fp[toff+1];
float nb = (1-u)*(1-v)*fp[toff+2];
toff = (iy+1)*fgrowsz + ix*nfgchs;
nr += (1-u)*v*fp[toff];
ng += (1-u)*v*fp[toff+1];
nb += (1-u)*v*fp[toff+2];
toff = iy*fgrowsz + (ix+1)*nfgchs;
nr += u*(1-v)*fp[toff];
ng += u*(1-v)*fp[toff+1];
nb += u*(1-v)*fp[toff+2];
toff = (iy+1)*fgrowsz + (ix+1)*nfgchs;
nr += u*v*fp[toff];
ng += u*v*fp[toff+1];
nb += u*v*fp[toff+2];
bp[soff] = (unsigned char)nr;
bp[soff+1] = (unsigned char)ng;
bp[soff+2] = (unsigned char)nb;
}
} /* end for(i=...) */
} /* end for(j=...) */
gdk_draw_pixbuf(d, NULL, bgbuf, xoff, yoff, 0, 0, bgwidth, bgheight, GDK_RGB_DITHER_NONE, 0, 0);
g_object_unref(bgbuf);
g_object_unref(fgbuf);
}
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