Workaround for pango kerning bug.

Fixes bug #698777.  This is a workaround for pango-cairo bug #700592, which is
a regression of bug #341481 which was originally fixed back in 2009.  This
workaround works by rendering the font at device scale rather than world scale.
To make this work the actual font size is manually scaled appropriately to
compensate for this.

diff --git a/src/label-text.c b/src/label-text.c
index 3f0305f91532a58cfb44ff9db8f609ce5419fdf0..287d3cc15b8625fc39dd13e173163c12c38de3b8 100644 (file)
--- a/src/label-text.c
+++ b/src/label-text.c
@@ -1115,13 +1115,24 @@ set_text_path (glLabelText      *this,
         PangoLayout          *layout;
         PangoStyle            style;
         PangoFontDescription *desc;
+        gdouble               scale_x, scale_y;
         cairo_font_options_t *font_options;
         PangoContext         *context;
 
 
         gl_debug (DEBUG_LABEL, "START");
 
+        /*
+         * Workaround for pango Bug#700592, which is a regression of Bug#341481.
+         * Render font at device scale and scale font size accordingly.
+         */
+        scale_x = 1.0;
+        scale_y = 1.0;
+        cairo_device_to_user_distance (cr, &scale_x, &scale_y);
+        scale_x = fabs (scale_x);
+        scale_y = fabs (scale_y);
         cairo_save (cr);
+        cairo_scale (cr, scale_x, scale_y);
 
         gl_label_object_get_size (GL_LABEL_OBJECT (this), &object_w, &object_h);
         gl_label_object_get_raw_size (GL_LABEL_OBJECT (this), &raw_w, &raw_h);
@@ -1159,20 +1170,20 @@ set_text_path (glLabelText      *this,
         desc = pango_font_description_new ();
         pango_font_description_set_family (desc, this->priv->font_family);
         pango_font_description_set_weight (desc, this->priv->font_weight);
-        pango_font_description_set_size   (desc, font_size * PANGO_SCALE);
+        pango_font_description_set_size   (desc, font_size * PANGO_SCALE / scale_x);
         pango_font_description_set_style  (desc, style);
         pango_layout_set_font_description (layout, desc);
         pango_font_description_free       (desc);
 
         pango_layout_set_text (layout, text, -1);
-        pango_layout_set_spacing (layout, font_size * (this->priv->line_spacing-1) * PANGO_SCALE);
+        pango_layout_set_spacing (layout, font_size * (this->priv->line_spacing-1) * PANGO_SCALE / scale_x);
         if (raw_w == 0.0)
         {
                 pango_layout_set_width (layout, -1);
         }
         else
         {
-                pango_layout_set_width (layout, object_w * PANGO_SCALE);
+                pango_layout_set_width (layout, object_w * PANGO_SCALE / scale_x);
         }
         pango_layout_set_wrap (layout, PANGO_WRAP_WORD);
         pango_layout_set_alignment (layout, this->priv->align);
@@ -1181,17 +1192,17 @@ set_text_path (glLabelText      *this,
         switch (this->priv->valign)
         {
         case GL_VALIGN_VCENTER:
-                y = (object_h - ih) / 2;
+                y = (object_h/scale_x - ih) / 2;
                 break;
         case GL_VALIGN_BOTTOM:
-                y = object_h - ih;
+                y = object_h/scale_x - ih;
                 break;
         default:
                 y = 0;
                 break;
         }
 
-        cairo_move_to (cr, GL_LABEL_TEXT_MARGIN, y);
+        cairo_move_to (cr, GL_LABEL_TEXT_MARGIN/scale_x, y);
         pango_cairo_layout_path (cr, layout);
 
         g_object_unref (layout);