[swell-foop] Support window resizing

[Robert Roth <robertroth src gnome org>]

commit 10759b3edbb6b249576702886b6146bf29a2c4f8
Author: Robert Mibus <mibus mibus org>
Date:   Fri Jan 29 20:56:58 2021 +1100

    Support window resizing
    
    Fixes #1

 data/ui/swell-foop.ui |  2 +-
 src/game-view.vala    | 28 ++++++++++++++++++++++++++--
 2 files changed, 27 insertions(+), 3 deletions(-)
---
diff --git a/data/ui/swell-foop.ui b/data/ui/swell-foop.ui
index f7a3f20..b99a037 100644
--- a/data/ui/swell-foop.ui
+++ b/data/ui/swell-foop.ui
@@ -135,7 +135,7 @@
   </menu>
   <requires lib="gtk+" version="3.12"/>
   <template class="SwellFoopWindow" parent="GtkApplicationWindow">
-    <property name="resizable">False</property>
+    <property name="resizable">True</property>
     <property name="icon-name">org.gnome.SwellFoop</property>
     <!-- Translators: title of the window displayed by window managers; name of the application -->
     <property name="title" translatable="yes">Swell Foop</property>
diff --git a/src/game-view.vala b/src/game-view.vala
index 69b50b8..e388be3 100644
--- a/src/game-view.vala
+++ b/src/game-view.vala
@@ -32,12 +32,36 @@ private class GameView : GtkClutter.Embed
 
         /* Request an appropriate size for the game view */
         init_size ();
+
+        /* Window resizes should trigger view scaling updates */
+        this.configure_event.connect(configure_event_cb);
     }
 
     private void init_size ()
     {
-        stage.set_size (group.width, group.height);
-        set_size_request ((int) stage.width, (int) stage.height);
+        // Force the clutter widget to have a minimum size of the Game View's
+        // size (this will be based on the tile size and arrangement).
+        set_size_request ((int) group.width, (int) group.height);
+
+        // Work out what the largest scale factor we can use is, to fit within
+        // the window.
+        var w_scale = stage.width / group.width;
+        var h_scale = stage.height / group.height;
+        var scale = w_scale < h_scale ? w_scale : h_scale;
+
+        // Set the view to that scale, and move the view within the clutter
+        // widget to match (creating implicit black borders for windows that
+        // aren't perfectly shaped for the board.
+        group.set_scale(scale, scale);
+        group.set_position(
+                (stage.width - scale * group.width) / 2,
+                (stage.height - scale * group.height) / 2);
+    }
+
+    private bool configure_event_cb (Gtk.Widget widget, Gdk.Event event)
+    {
+        init_size ();
+        return false;
     }
 
     /*\