- correct documentation of default of raw image interleave read

[imager.git] / paste.im

diff --git a/paste.im b/paste.im
index 669c6ca9913575cae10d08c4173546141b92eb07..ef7d1445a64d773a4306eed65221d3ae36a26227 100644 (file)
--- a/paste.im
+++ b/paste.im
@@ -325,7 +325,125 @@ i_adapt_fcolors_bg
     }
     break;
   }
+}
+
+/*
+=item i_gsamp_bg(im, l, r, y, samples, out_channels, bg)
+
+=item i_gsampf_bg(im, l, r, y, samples, out_channels, bg)
+
+This is similar to i_adapt_colors_bg() except it can only strip an
+alpha channel.  It cannot be used to convert a source RGB image to
+greyscale.
+
+The samples parameter MUST include enough space for all samples of the
+source image.
+
+=cut
+*/
+int
+#ifdef IM_EIGHT_BIT
+i_gsamp_bg
+#else
+i_gsampf_bg
+#endif
+(i_img *im, int l, int r, int y, IM_SAMPLE_T *samples, 
+ int out_channels, IM_COLOR const *bg) {
+  if (out_channels == im->channels)
+    return IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
+  
+  switch (out_channels) {
+  case 1:
+    switch (im->channels) {
+    case 2:
+      {
+       int x;
+       IM_SAMPLE_T *inp = samples, *outp = samples;
+       IM_WORK_T grey_bg = IM_ROUND(color_to_grey(bg));
+       int count;
+
+       count = IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
+       if (!count)
+         return 0;
+       
+       for (x = l; x < r; ++x) {
+         *outp++ = ( inp[0] * inp[1] +
+                     grey_bg * (IM_SAMPLE_MAX - inp[1])) / IM_SAMPLE_MAX;
+         inp += 2;
+       }
+
+       return count;
+      }
+      break;
+
+    default:
+      i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
+      break;
+    }
+    break;
+  case 3:
+    switch (im->channels) {
+    case 1:
+      {
+       int channels[3] = { 0, 0, 0 };
+       return IM_GSAMP(im, l, r, y, samples, channels, out_channels);
+      }
+    case 2:
+      {
+       int x, ch;
+       IM_SAMPLE_T *inp = samples, *outp = samples;
+       int count;
+       int channels[4] = { 0, 0, 0, 1 };
+
+       count = IM_GSAMP(im, l, r, y, samples, channels, im->channels);
+       if (!count)
+         return 0;
+       
+       for (x = l; x < r; ++x) {
+         IM_WORK_T alpha = inp[3];
+         for (ch = 0; ch < 3; ++ch) {
+           *outp++ = ( *inp++ * alpha +
+                       bg->channel[ch] * (IM_SAMPLE_MAX - alpha)) / IM_SAMPLE_MAX;
+         }
+         ++inp;
+       }
+
+       return count;
+      }
+
+    case 4:
+      {
+       int x, ch;
+       IM_SAMPLE_T *inp = samples, *outp = samples;
+       int count;
+
+       count = IM_GSAMP(im, l, r, y, samples, NULL, im->channels);
+       if (!count)
+         return 0;
+       
+       for (x = l; x < r; ++x) {
+         IM_WORK_T alpha = inp[3];
+         for (ch = 0; ch < 3; ++ch) {
+           *outp++ = ( *inp++ * alpha +
+                       bg->channel[ch] * (IM_SAMPLE_MAX - alpha)) / IM_SAMPLE_MAX;
+         }
+         ++inp;
+       }
+
+       return count;
+      }
+      break;
+    default:
+      i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
+      break;
+    }
+    break;
+
+  default:
+    i_fatal(0, "i_gsamp_bg() can only remove alpha channels");
+  }
 
+  return 0;
 }
 
 #/code