Fix GTK3 size calculations in unifontsel_new.

It turns out that in GTK3, if you instantiate a GtkLabel and
immediately try to find out its preferred size, you get back zero for
both dimensions. Presumably none of that gets figured out properly
until the widget is displayed, or some such.

However, you can retrieve the PangoLayout from the label immediately
and ask Pango for the dimensions of that. That seems like a bit of a
bodge, but it works! The GTK3 unifont selector now comes out with all
the interface elements in sensible sizes - in particular, the preview
drawing area now has non-zero height.

diff --git a/unix/gtkfont.c b/unix/gtkfont.c
index bb6afc5fcd203c34ded1d6d79d6aafcea31038e4..7230e015e95d731d71cf71c45a6b4e77e0a6d01f 100644 (file)
--- a/unix/gtkfont.c
+++ b/unix/gtkfont.c
@@ -2914,6 +2914,39 @@ static gint unifontsel_configure_area(GtkWidget *widget,
     return TRUE;
 }
 
+static void get_label_text_dimensions(const char *text,
+                                      int *width, int *height)
+{
+    /*
+     * Determine the dimensions of a piece of text in the standard
+     * font used in GTK interface elements like labels. We do this by
+     * instantiating an actual GtkLabel, and then querying its size.
+     *
+     * But GTK2 and GTK3 require us to query the size completely
+     * differently. I'm sure there ought to be an easier approach than
+     * the way I'm doing this in GTK3, too!
+     */
+    GtkWidget *label = gtk_label_new(text);
+
+#if GTK_CHECK_VERSION(3,0,0)
+    PangoLayout *layout = gtk_label_get_layout(GTK_LABEL(label));
+    PangoRectangle logrect;
+    pango_layout_get_extents(layout, NULL, &logrect);
+    *width = logrect.width / PANGO_SCALE;
+    *height = logrect.height / PANGO_SCALE;
+#else
+    GtkRequisition req;
+    gtk_widget_size_request(label, &req);
+    *width = req.width;
+    *height = req.height;
+#endif
+
+    g_object_ref_sink(G_OBJECT(label));
+#if GTK_CHECK_VERSION(2,10,0)
+    g_object_unref(label);
+#endif
+}
+
 unifontsel *unifontsel_new(const char *wintitle)
 {
     unifontsel_internal *fs = snew(unifontsel_internal);
@@ -2927,25 +2960,22 @@ unifontsel *unifontsel_new(const char *wintitle)
     fs->selected = NULL;
 
     {
+        int width, height;
+
        /*
         * Invent some magic size constants.
         */
-       GtkRequisition req;
-       label = gtk_label_new("Quite Long Font Name (Foundry)");
-       gtk_widget_size_request(label, &req);
-       font_width = req.width;
-       lists_height = 14 * req.height;
-       preview_height = 5 * req.height;
-       gtk_label_set_text(GTK_LABEL(label), "Italic Extra Condensed");
-       gtk_widget_size_request(label, &req);
-       style_width = req.width;
-       gtk_label_set_text(GTK_LABEL(label), "48000");
-       gtk_widget_size_request(label, &req);
-       size_width = req.width;
-        g_object_ref_sink(G_OBJECT(label));
-#if GTK_CHECK_VERSION(2,10,0)
-       g_object_unref(label);
-#endif
+       get_label_text_dimensions("Quite Long Font Name (Foundry)",
+                                  &width, &height);
+       font_width = width;
+       lists_height = 14 * height;
+       preview_height = 5 * height;
+
+       get_label_text_dimensions("Italic Extra Condensed", &width, &height);
+       style_width = width;
+
+       get_label_text_dimensions("48000", &width, &height);
+       size_width = width;
     }
 
     /*