JS: Fix stride calculation for images with odd widths.

strukturag · Nov 2, 2020 · d97b79f · d97b79f
1 parent 3a023f9
commit d97b79f
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Showing 2 changed files with 14 additions and 9 deletions.
diff --git a/libheif/heif_emscripten.h b/libheif/heif_emscripten.h
@@ -88,6 +88,10 @@ static emscripten::val heif_js_context_get_list_of_top_level_image_IDs(
   return result;
 }
 
+static int round_odd(int v) {
+  return (int) ((v / 2.0) + 0.5);
+}
+
 static emscripten::val heif_js_decode_image(struct heif_image_handle* handle,
                                             enum heif_colorspace colorspace, enum heif_chroma chroma)
 {
@@ -122,13 +126,13 @@ static emscripten::val heif_js_decode_image(struct heif_image_handle* handle,
       int stride_v;
       const uint8_t* plane_v = heif_image_get_plane_readonly(image,
                                                              heif_channel_Cr, &stride_v);
-      data.resize((width * height) + (width * height / 2));
+      data.resize((width * height) + (2 * round_odd(width) * round_odd(height)));
       char* dest = const_cast<char*>(data.data());
       strided_copy(dest, plane_y, width, height, stride_y);
       strided_copy(dest + (width * height), plane_u,
-                   width / 2, height / 2, stride_u);
-      strided_copy(dest + (width * height) + (width * height / 4),
-                   plane_v, width / 2, height / 2, stride_v);
+                   round_odd(width), round_odd(height), stride_u);
+      strided_copy(dest + (width * height) + (round_odd(width) * round_odd(height)),
+                   plane_v, round_odd(width), round_odd(height), stride_v);
     }
       break;
     case heif_colorspace_RGB: {

diff --git a/post.js b/post.js
@@ -75,12 +75,13 @@ HeifImage.prototype.display = function(image_data, callback) {
         var x2;
         var i = 0;
         var maxi = w*h;
-        var y = this.data;
-        var u = this.data.subarray(w * h, w * h + (w * h / 4));
-        var v = this.data.subarray(w * h + (w * h / 4), w * h + (w * h / 2));
         var stridey = w;
-        var strideu = Math.floor(w / 2);
-        var stridev = Math.floor(w / 2);
+        var strideu = Math.ceil(w / 2);
+        var stridev = Math.ceil(w / 2);
+        var h2 = Math.ceil(h / 2);
+        var y = this.data;
+        var u = this.data.subarray(stridey * h, stridey * h + (strideu * h2));
+        var v = this.data.subarray(stridey * h + (strideu * h2), stridey * h + (strideu * h2) + (stridev * h2));
         var dest = image_data.data;
         while (i < maxi) {
             x2 = (xpos >> 1);