[view-cairo] Minor subpixel-bits

util/helper-cairo.hh

@@ -585,13 +585,13 @@ struct helper_cairo_line_t {
 		       unsigned             utf8_len_,
 		       hb_buffer_t         *buffer,
 		       hb_bool_t            utf8_clusters,
-		       int                  scale_bits) :
+		       unsigned             subpixel_bits) :
     utf8 (utf8_ ? g_strndup (utf8_, utf8_len_) : nullptr),
     utf8_len (utf8_len_)
   {
     hb_cairo_glyphs_from_buffer (buffer,
 				 utf8_clusters,
-				 1 << -scale_bits, 1 << -scale_bits,
+				 1 << subpixel_bits, 1 << subpixel_bits,
 				 0., 0.,
 				 utf8, utf8_len,
 				 &glyphs, &num_glyphs,

util/view-cairo.hh

@@ -48,7 +48,7 @@ struct view_cairo_t : view_options_t, output_options_t<>
   void init (hb_buffer_t *buffer, const font_options_t *font_opts)
   {
     lines = g_array_new (false, false, sizeof (helper_cairo_line_t));
-    scale_bits = - (int) font_opts->subpixel_bits;
+    subpixel_bits = font_opts->subpixel_bits;
   }
   void new_line () {}
   void consume_text (hb_buffer_t  *buffer,
@@ -63,7 +63,7 @@ struct view_cairo_t : view_options_t, output_options_t<>
 		       hb_bool_t     utf8_clusters)
   {
     direction = hb_buffer_get_direction (buffer);
-    helper_cairo_line_t l (text, text_len, buffer, utf8_clusters, scale_bits);
+    helper_cairo_line_t l (text, text_len, buffer, utf8_clusters, subpixel_bits);
     g_array_append_val (lines, l);
   }
   void finish (hb_buffer_t *buffer, const font_options_t *font_opts)
@@ -87,7 +87,7 @@ struct view_cairo_t : view_options_t, output_options_t<>
 
   hb_direction_t direction = HB_DIRECTION_INVALID; // Remove this, make segment_properties accessible
   GArray *lines = nullptr;
-  int scale_bits = 0;
+  unsigned subpixel_bits = 0;
 };
 
 inline void
@@ -106,9 +106,9 @@ view_cairo_t::render (const font_options_t *font_opts)
   {
     hb_font_extents_t hb_extents;
     hb_font_get_extents_for_direction (font, direction, &hb_extents);
-    font_extents.ascent = scalbn ((double) hb_extents.ascender, scale_bits);
-    font_extents.descent = -scalbn ((double) hb_extents.descender, scale_bits);
-    font_extents.line_gap = scalbn ((double) hb_extents.line_gap, scale_bits);
+    font_extents.ascent = scalbn ((double) hb_extents.ascender, - (int) subpixel_bits);
+    font_extents.descent = -scalbn ((double) hb_extents.descender, - (int) subpixel_bits);
+    font_extents.line_gap = scalbn ((double) hb_extents.line_gap, - (int) subpixel_bits);
     have_font_extents = true;
   }