- in some cases it's possible for giflib/libungif to return color

[imager.git] / image.c

diff --git a/image.c b/image.c
index 18a9796b2f90d9cb62eae8080dd391ad9a60093f..03a06f44f7633889a8cf88c186b292c8d699ad52 100644 (file)
--- a/image.c
+++ b/image.c
@@ -697,104 +697,6 @@ i_copy(i_img *src) {
 }
 
 
-/*
-=item i_rubthru(im, src, tx, ty, src_minx, src_miny, src_maxx, src_maxy )
-
-=category Image
-
-Takes the sub image I<src[src_minx, src_maxx)[src_miny, src_maxy)> and
-overlays it at (I<tx>,I<ty>) on the image object.
-
-The alpha channel of each pixel in I<src> is used to control how much
-the existing colour in I<im> is replaced, if it is 255 then the colour
-is completely replaced, if it is 0 then the original colour is left 
-unmodified.
-
-=cut
-*/
-
-int
-i_rubthru(i_img *im, i_img *src, int tx, int ty, int src_minx, int src_miny,
-         int src_maxx, int src_maxy) {
-  int x, y, ttx, tty;
-  int chancount;
-  int chans[3];
-  int alphachan;
-  int ch;
-
-  mm_log((1,"i_rubthru(im %p, src %p, tx %d, ty %d, src_minx %d, "
-         "src_miny %d, src_maxx %d, src_maxy %d)\n",
-         im, src, tx, ty, src_minx, src_miny, src_maxx, src_maxy));
-  i_clear_error();
-
-  if (im->channels == 3 && src->channels == 4) {
-    chancount = 3;
-    chans[0] = 0; chans[1] = 1; chans[2] = 2;
-    alphachan = 3;
-  }
-  else if (im->channels == 3 && src->channels == 2) {
-    chancount = 3;
-    chans[0] = chans[1] = chans[2] = 0;
-    alphachan = 1;
-  }
-  else if (im->channels == 1 && src->channels == 2) {
-    chancount = 1;
-    chans[0] = 0;
-    alphachan = 1;
-  }
-  else {
-    i_push_error(0, "rubthru can only work where (dest, src) channels are (3,4), (3,2) or (1,2)");
-    return 0;
-  }
-
-  if (im->bits <= 8) {
-    /* if you change this code, please make sure the else branch is
-       changed in a similar fashion - TC */
-    int alpha;
-    i_color pv, orig, dest;
-    tty = ty;
-    for(y = src_miny; y < src_maxy; y++) {
-      ttx = tx;
-      for(x = src_minx; x < src_maxx; x++) {
-        i_gpix(src, x,   y,   &pv);
-        i_gpix(im,  ttx, tty, &orig);
-        alpha = pv.channel[alphachan];
-        for (ch = 0; ch < chancount; ++ch) {
-          dest.channel[ch] = (alpha * pv.channel[chans[ch]]
-                              + (255 - alpha) * orig.channel[ch])/255;
-        }
-        i_ppix(im, ttx, tty, &dest);
-       ttx++;
-      }
-      tty++;
-    }
-  }
-  else {
-    double alpha;
-    i_fcolor pv, orig, dest;
-
-    tty = ty;
-    for(y = src_miny; y < src_maxy; y++) {
-      ttx = tx;
-      for(x = src_minx; x < src_maxx; x++) {
-        i_gpixf(src, x,   y,   &pv);
-        i_gpixf(im,  ttx, tty, &orig);
-        alpha = pv.channel[alphachan];
-        for (ch = 0; ch < chancount; ++ch) {
-          dest.channel[ch] = alpha * pv.channel[chans[ch]]
-           + (1 - alpha) * orig.channel[ch];
-        }
-        i_ppixf(im, ttx, tty, &dest);
-        ttx++;
-      }
-      tty++;
-    }
-  }
-
-  return 1;
-}
-
-
 /*
 =item i_flipxy(im, axis)
 
@@ -2251,8 +2153,77 @@ i_test_format_probe(io_glue *data, int length) {
   return NULL;
 }
 
+/*
+=item i_img_is_monochrome(img, &zero_is_white)
+
+Tests an image to check it meets our monochrome tests.
+
+The idea is that a file writer can use this to test where it should
+write the image in whatever bi-level format it uses, eg. pbm for pnm.
+
+For performance of encoders we require monochrome images:
+
+=over
+
+=item *
+
+be paletted
 
+=item *
 
+have a palette of two colors, containing only (0,0,0) and
+(255,255,255) in either order.
+
+=back
+
+zero_is_white is set to non-zero iff the first palette entry is white.
+
+=cut
+*/
+
+int
+i_img_is_monochrome(i_img *im, int *zero_is_white) {
+  if (im->type == i_palette_type
+      && i_colorcount(im) == 2) {
+    i_color colors[2];
+    i_getcolors(im, 0, colors, 2);
+    if (im->channels == 3) {
+      if (colors[0].rgb.r == 255 && 
+          colors[0].rgb.g == 255 &&
+          colors[0].rgb.b == 255 &&
+          colors[1].rgb.r == 0 &&
+          colors[1].rgb.g == 0 &&
+          colors[1].rgb.b == 0) {
+        *zero_is_white = 0;
+        return 1;
+      }
+      else if (colors[0].rgb.r == 0 && 
+               colors[0].rgb.g == 0 &&
+               colors[0].rgb.b == 0 &&
+               colors[1].rgb.r == 255 &&
+               colors[1].rgb.g == 255 &&
+               colors[1].rgb.b == 255) {
+        *zero_is_white = 1;
+        return 1;
+      }
+    }
+    else if (im->channels == 1) {
+      if (colors[0].channel[0] == 255 &&
+          colors[1].channel[1] == 0) {
+        *zero_is_white = 0;
+        return 1;
+      }
+      else if (colors[0].channel[0] == 0 &&
+               colors[0].channel[0] == 255) {
+        *zero_is_white = 1;
+        return 1;         
+      }
+    }
+  }
+
+  *zero_is_white = 0;
+  return 0;
+}
 
 /*
 =back