[gnome-sudoku/mcatanzaro/print-rtl] Use pango to format sudoku titles when printing

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 868d3b9a51ec0968cfdb78bb491e9d6fa3ab6679
Author: Michael Catanzaro <mcatanzaro redhat com>
Date:   Thu Jul 22 15:35:31 2021 -0500

    Use pango to format sudoku titles when printing
    
    Currently they are printed using cairo's toy text API, which is good
    enough to print individual numbers in our Sudoku grid, but not nearly
    good enough to handle internationalized complex text. We can fix this by
    switching to Pango instead.
    
    Fixes #52

 src/sudoku-printer.vala | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)
---
diff --git a/src/sudoku-printer.vala b/src/sudoku-printer.vala
index 7b5fcbf..eb638e7 100644
--- a/src/sudoku-printer.vala
+++ b/src/sudoku-printer.vala
@@ -93,18 +93,27 @@ public class SudokuPrinter : GLib.Object {
 
         uint index = 0;
 
+        var pango_context = Pango.cairo_create_context (cr);
+        Pango.cairo_context_set_font_options (pango_context, Gdk.Screen.get_default ().get_font_options ());
+
         foreach (SudokuBoard sudoku in sudokus_on_page)
         {
             double left = margin_x + (index % n_across) * (best_square_size + margin_x);
             double top = margin_y + label_extents.height + (index / n_across) * (best_square_size + margin_y 
+ label_extents.height);
 
             var label = sudoku.difficulty_category.to_string ();
-            set_label_font (cr);
+            var layout = new Pango.Layout (pango_context);
+            layout.set_font_description (Pango.FontDescription.from_string ("Sans Bold 12"));
+            layout.set_text (label, -1);
+
+            int layout_width;
+            int layout_height;
+            layout.get_size (out layout_width, out layout_height);
+            layout_width /= Pango.SCALE;
+            layout_height /= Pango.SCALE;
+            cr.move_to (left + (best_square_size - layout_width) / 2, top - layout_height / 2);
             cr.set_source_rgb (0, 0, 0);
-            Cairo.TextExtents extents;
-            cr.text_extents (label, out extents);
-            cr.move_to (left + (best_square_size - extents.width) / 2, top - extents.height / 2);
-            cr.show_text (label);
+            Pango.cairo_show_layout (cr, layout);
 
             draw_sudoku (cr, sudoku, best_square_size, left, top);