[truetype] Allow linear scaling for unhinted rendering (#50470).

* src/truetype/ttdriver.c (tt_size_request): Revert change from
2011-07-16; the intended metrics fix seems now to be implemented in
a different way, making the patch unnecessary.  Note that this
change was usually patched out by all major GNU/Linux distributions
due to heavy side effects.

* src/truetype/ttgload.c (compute_glyph_metrics, TT_Load_Glyph):
Refer to the metrics of the `TT_Size' object.

ChangeLog

@@ -1,3 +1,16 @@
+2017-03-30  Werner Lemberg  <wl@gnu.org>
+
+	[truetype] Allow linear scaling for unhinted rendering (#50470).
+
+	* src/truetype/ttdriver.c (tt_size_request): Revert change from
+	2011-07-16; the intended metrics fix seems now to be implemented in
+	a different way, making the patch unnecessary.  Note that this
+	change was usually patched out by all major GNU/Linux distributions
+	due to heavy side effects.
+
+	* src/truetype/ttgload.c (compute_glyph_metrics, TT_Load_Glyph):
+	Refer to the metrics of the `TT_Size' object.
+
 2017-03-29  Werner Lemberg  <wl@gnu.org>
 
 	[truetype] Fix thinko related to PS name of default named instance.

src/truetype/ttdriver.c

@@ -356,8 +356,7 @@
 
     if ( FT_IS_SCALABLE( size->face ) )
     {
-      error                = tt_size_reset( ttsize, 0 );
-      ttsize->root.metrics = ttsize->metrics;
+      error = tt_size_reset( ttsize, 0 );
 
 #ifdef TT_USE_BYTECODE_INTERPRETER
       /* for the `MPS' bytecode instruction we need the point size */

src/truetype/ttgload.c

@@ -2037,7 +2037,7 @@
 
     y_scale = 0x10000L;
     if ( ( loader->load_flags & FT_LOAD_NO_SCALE ) == 0 )
-      y_scale = size->root.metrics.y_scale;
+      y_scale = size->metrics.y_scale;
 
     if ( glyph->format != FT_GLYPH_FORMAT_COMPOSITE )
       FT_Outline_Get_CBox( &glyph->outline, &bbox );
@@ -2069,7 +2069,7 @@
 
 
       widthp = tt_face_get_device_metrics( face,
-                                           size->root.metrics.x_ppem,
+                                           size->metrics.x_ppem,
                                            glyph_index );
 
 #ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY
@@ -2636,11 +2636,11 @@
           if ( !glyph->metrics.horiAdvance && glyph->linearHoriAdvance )
             glyph->metrics.horiAdvance =
               FT_MulFix( glyph->linearHoriAdvance,
-                         size->root.metrics.x_scale );
+                         size->metrics.x_scale );
           if ( !glyph->metrics.vertAdvance && glyph->linearVertAdvance )
             glyph->metrics.vertAdvance =
               FT_MulFix( glyph->linearVertAdvance,
-                         size->root.metrics.y_scale );
+                         size->metrics.y_scale );
         }
 
         return FT_Err_Ok;
@@ -2736,7 +2736,7 @@
     /* TrueType glyphs at all sizes using the bytecode interpreter. */
     /*                                                              */
     if ( !( load_flags & FT_LOAD_NO_SCALE ) &&
-         size->root.metrics.y_ppem < 24     )
+         size->metrics.y_ppem < 24          )
       glyph->outline.flags |= FT_OUTLINE_HIGH_PRECISION;
 
   Exit: