X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=images%2Fio-libpng.c;h=f15955a64cf83c045bd953cb1afa33fd96908b96;hb=94022b1a1e317871b302946b595b2e890f4f1853;hp=1e1704f8cef4547fe1b28766c4c9e5c716838117;hpb=422234aee83909200561bcce45f6bc1ed84f4789;p=libucw.git

diff --git a/images/io-libpng.c b/images/io-libpng.c
index 1e1704f8..f15955a6 100644
--- a/images/io-libpng.c
+++ b/images/io-libpng.c
@@ -224,10 +224,20 @@ libpng_read_data(struct image_io *io)
 	  }
 	else
 	  png_set_palette_to_rgb(rd->png_ptr);
-	if ((io->flags & IMAGE_ALPHA) || (io->flags & IMAGE_PIXEL_FORMAT) == (COLOR_SPACE_RGB | IMAGE_PIXELS_ALIGNED))
-          png_set_add_alpha(rd->png_ptr, 255, PNG_FILLER_AFTER);
+	if (!(io->flags & IMAGE_ALPHA))
+	  {
+	    if (io->flags & IMAGE_IO_USE_BACKGROUND)
+	      {
+                png_set_add_alpha(rd->png_ptr, 255, PNG_FILLER_AFTER);
+	        read_flags = (read_flags | IMAGE_ALPHA) & IMAGE_CHANNELS_FORMAT;
+	      }
+	    else if ((io->flags & IMAGE_PIXEL_FORMAT) == (COLOR_SPACE_RGB | IMAGE_PIXELS_ALIGNED))
+              png_set_add_alpha(rd->png_ptr, 255, PNG_FILLER_AFTER);
+            else
+	      png_set_strip_alpha(rd->png_ptr);
+	  }
 	else
-	  png_set_strip_alpha(rd->png_ptr);
+          png_set_add_alpha(rd->png_ptr, 255, PNG_FILLER_AFTER);
 	break;
       case PNG_COLOR_TYPE_GRAY:
 	if ((io->flags & IMAGE_COLOR_SPACE) == COLOR_SPACE_RGB)
@@ -241,7 +251,7 @@ libpng_read_data(struct image_io *io)
 	if (!(io->flags & IMAGE_ALPHA))
 	  {
 	    if (io->flags & IMAGE_IO_USE_BACKGROUND)
-	      read_flags |= IMAGE_ALPHA;
+	      read_flags = (read_flags | IMAGE_ALPHA) & IMAGE_CHANNELS_FORMAT;
 	    else
               png_set_strip_alpha(rd->png_ptr);
 	  }  
@@ -255,13 +265,11 @@ libpng_read_data(struct image_io *io)
       case PNG_COLOR_TYPE_RGB_ALPHA:
 	if ((io->flags & IMAGE_COLOR_SPACE) == COLOR_SPACE_GRAYSCALE)
 	  png_set_rgb_to_gray_fixed(rd->png_ptr, 1, 21267, 71514);
-	if (!(io->flags & IMAGE_ALPHA) && (io->flags & IMAGE_PIXEL_FORMAT) != (COLOR_SPACE_RGB | IMAGE_PIXELS_ALIGNED))
-	  {
-	    if (io->flags & IMAGE_IO_USE_BACKGROUND)
-	      read_flags |= IMAGE_ALPHA;
-	    else
-              png_set_strip_alpha(rd->png_ptr);
-	  }
+	if (!(io->flags & IMAGE_ALPHA))
+	  if (io->flags & IMAGE_IO_USE_BACKGROUND)
+	    read_flags = (read_flags | IMAGE_ALPHA) & IMAGE_CHANNELS_FORMAT;
+	  else if ((io->flags & IMAGE_PIXEL_FORMAT) != (COLOR_SPACE_RGB | IMAGE_PIXELS_ALIGNED))
+            png_set_strip_alpha(rd->png_ptr);
 	break;
       default:
 	ASSERT(0);