+static CanonImage *convert_page(Snapshot *sn) {
+ ShMask shiftmasks[3];
+ CanonImage *im;
+
+ fprintf(screenshots_file,
+ "P6\n"
+ "%d %d\n"
+ "255\n", sn->width, sn->height);
+
+#define COMPUTE_SHIFT_MASK(ix, rgb) \
+ compute_shift_mask(&shiftmasks[ix], sn->rgb##_mask)
+ COMPUTE_SHIFT_MASK(0, red);
+ COMPUTE_SHIFT_MASK(1, green);
+ COMPUTE_SHIFT_MASK(2, blue);
+
+ CANONICALISE_IMAGE(im, sn->width, sn->height, {
+ long xrgb= XGetPixel(sn, x, y);
+ int i;
+ rgb= 0;
+ for (i=0; i<3; i++) {
+ rgb <<= 8;
+ unsigned long sample=
+ ((xrgb << shiftmasks[i].lshift)
+ >> shiftmasks[i].rshift) & SAMPLEMASK;
+ rgb |= sample;
+ fputc(sample, screenshots_file);
+ }
+ });