Issue 3483: Pango font size should be calculated using rounding

So far, pango font size has been calculated using truncation.  Since
the calculation of font size may involve conversion of magnifications
to font-size and back, numerical errors can easily throw the
calculation slightly off.  For that reason, rounding is the
appropriate option here.

diff --git a/lily/pango-select.cc b/lily/pango-select.cc
index cb05b0c183037f6e4c472253288be2bbfaa89936..082bcd824374ca9b8907c36e28b6b601b83fdc85 100644 (file)
--- a/lily/pango-select.cc
+++ b/lily/pango-select.cc
@@ -19,6 +19,7 @@
 
 #include "dimensions.hh"
 #include "all-font-metrics.hh"
+#include "libc-extension.hh"
 #include "output-def.hh"
 #include "pango-font.hh"
 
@@ -54,7 +55,8 @@ properties_to_pango_description (SCM chain, Real text_size)
                                  0.0);
   Real size = text_size * pow (2.0, step / 6.0);
 
-  pango_font_description_set_size (description, gint (size * PANGO_SCALE));
+  pango_font_description_set_size (description,
+                                   gint (my_round (size * PANGO_SCALE)));
   return description;
 }
 

diff --git a/lily/paper-def.cc b/lily/paper-def.cc
index aa3a296c1f4bca5f179af85b459ed41f70b825c0..4c6dc86ebeb8d645477920e9e4aa35c4b45cdd5a 100644 (file)
--- a/lily/paper-def.cc
+++ b/lily/paper-def.cc
@@ -18,6 +18,7 @@
 */
 
 #include "dimensions.hh"
+#include "libc-extension.hh"
 #include "output-def.hh"
 #include "modified-font-metric.hh"
 #include "pango-font.hh"
@@ -92,9 +93,9 @@ find_pango_font (Output_def *layout, SCM descr, Real factor)
   PangoFontDescription *description
     = pango_font_description_from_string (scm_i_string_chars (descr));
 
-  pango_font_description_set_size (description,
-                                   gint (factor *
-                                         pango_font_description_get_size (description)));
+  pango_font_description_set_size
+    (description,
+     gint (my_round (factor * pango_font_description_get_size (description))));
 
   Font_metric *fm = all_fonts_global->find_pango_font (description,
                                                        output_scale (layout));