shithub: freetype+ttf2subf

Download patch

ref: 0348c627b19864203c0eb3752f49850851a65200
parent: f27b4834b7dcf9d667fd5173106be0cddb0ec1c2
author: Dominik Röttsches <drott@chromium.org>
date: Tue Jun 29 16:51:32 EDT 2021 

[sfnt] Handle fonts without layer list in 'COLR' v1.

'COLR' v1 fonts do not necessarily need to have a layer list; for
this reason, 'fontTools' recently started generating fonts in a way
that drops the layer list if there are no layers in it.  This
results in the layer list offset becoming zero, which FreeType
treated as an invalid table.  Fix that and handle the case for layer
list offset being 0.  This slightly changes how we need to calculate
the starting offset for paints.

* src/sfnt/ttcolr.c (tt_face_load_colr): Handle case of layer list
offset being zero without outright rejecting table.

git/fs: mount .git/fs: mount/attach disallowed 
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2021-06-30  Dominik Röttsches  <drott@chromium.org>
+
+	[sfnt] Handle fonts without layer list in 'COLR' v1.
+
+	'COLR' v1 fonts do not necessarily need to have a layer list; for
+	this reason, 'fontTools' recently started generating fonts in a way
+	that drops the layer list if there are no layers in it.  This
+	results in the layer list offset becoming zero, which FreeType
+	treated as an invalid table.  Fix that and handle the case for layer
+	list offset being 0.  This slightly changes how we need to calculate
+	the starting offset for paints.
+
+	* src/sfnt/ttcolr.c (tt_face_load_colr): Handle case of layer list
+	offset being zero without outright rejecting table.
+
 2021-06-30  Alexei Podtelezhnikov  <apodtele@gmail.com>
 
 	* src/raster/ftraster.c (Render_Single_Pass): Simplify `band_stack'.
--- a/src/sfnt/ttcolr.c
+++ b/src/sfnt/ttcolr.c
@@ -186,24 +186,35 @@
 
       layer_offset_v1 = FT_NEXT_ULONG( p );
 
-      if ( !layer_offset_v1 || layer_offset_v1 >= table_size )
+      if ( layer_offset_v1 >= table_size )
         goto InvalidTable;
 
-      p1            = (FT_Byte*)( table + layer_offset_v1 );
-      num_layers_v1 = FT_PEEK_ULONG( p1 );
+      if ( layer_offset_v1 )
+      {
+        p1            = (FT_Byte*)( table + layer_offset_v1 );
+        num_layers_v1 = FT_PEEK_ULONG( p1 );
 
-      if ( num_layers_v1 * LAYER_V1_LIST_PAINT_OFFSET_SIZE >
-             table_size - layer_offset_v1 )
-        goto InvalidTable;
+        if ( num_layers_v1 * LAYER_V1_LIST_PAINT_OFFSET_SIZE >
+               table_size - layer_offset_v1 )
+          goto InvalidTable;
 
-      colr->num_layers_v1 = num_layers_v1;
-      colr->layers_v1     = p1;
+        colr->num_layers_v1 = num_layers_v1;
+        colr->layers_v1     = p1;
 
-      colr->paints_start_v1 =
-        FT_MIN( colr->base_glyphs_v1 +
-                  colr->num_base_glyphs_v1 * BASE_GLYPH_PAINT_RECORD_SIZE,
-                colr->layers_v1 +
-                  colr->num_layers_v1 * LAYER_V1_LIST_PAINT_OFFSET_SIZE );
+        colr->paints_start_v1 =
+            FT_MIN( colr->base_glyphs_v1 +
+                    colr->num_base_glyphs_v1 * BASE_GLYPH_PAINT_RECORD_SIZE,
+                    colr->layers_v1 +
+                    colr->num_layers_v1 * LAYER_V1_LIST_PAINT_OFFSET_SIZE );
+      }
+      else
+      {
+        colr->num_layers_v1   = 0;
+        colr->layers_v1       = 0;
+        colr->paints_start_v1 =
+          colr->base_glyphs_v1 +
+          colr->num_base_glyphs_v1 * BASE_GLYPH_PAINT_RECORD_SIZE;
+      }
     }
 
     colr->base_glyphs = (FT_Byte*)( table + base_glyph_offset );