[gnome-chess/mcatanzaro/gtk4] progress

[Michael Catanzaro <mcatanzaro src gnome org>]

commit db44047ed26278642d0e5b455cf6610b54b804e3
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Wed Dec 23 17:23:57 2020 -0600

    progress

 src/gnome-chess.vala | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)
---
diff --git a/src/gnome-chess.vala b/src/gnome-chess.vala
index 1eacd5d..69fdc63 100644
--- a/src/gnome-chess.vala
+++ b/src/gnome-chess.vala
@@ -1723,9 +1723,58 @@ Copyright © 2015–2016 Sahil Sareen""";
             return "∶\xE2\x80\x8E%02d".printf (time);
     }
 
+    /* Compute the largest possible size the timer label might ever want to take.
+     * The size of the characters may vary by font, but one digit will always
+     * be the largest.
+     */
+    private int compute_time_label_width_request (Cairo.Context c)
+        ensures (result > 0)
+    {
+        Cairo.TextExtents extents;
+        double max = 0;
+
+        c.text_extents ("000∶00", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("111∶11", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("222∶22", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("333∶33", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("444∶44", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("555∶55", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("666∶66", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("777∶77", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("888∶88", out extents);
+        max = (max > extents.width ? max : extents.width);
+        c.text_extents ("999∶99", out extents);
+        max = (max > extents.width ? max : extents.width);
+
+        /* Leave a little bit of room to the sides. */
+        return (int) Math.ceil (max) + 6;
+    }
+
     private void draw_time (Widget widget, Cairo.Context c, int width, int height, string text, double[] fg, 
double[] bg)
     {
-        c.scale (width, height);
+        /* We need to draw text on our cairo context to properly compute our
+         * required size. But the only place we are able to access the cairo
+         * context is here, the draw function. And we are not allowed to set our
+         * size inside the draw function. So the best we can do is schedule the
+         * size computation and queue draw again when that's done.
+         */
+        if (widget.width_request == -1)
+        {
+            Idle.add(() => {
+                widget.set_size_request (compute_time_label_width_request (c), -1);
+                widget.queue_draw ();
+                return Source.REMOVE;
+            });
+            return;
+        }
 
         double alpha = 1.0;
         if ((widget.get_state_flags () & StateFlags.INSENSITIVE) != 0)