keyboard: Add support for setting OSK keys with icons

Unused at the moment, but add the plumbing so that default key
definitions may specify symbolic icons that will be shown instead
of the text.

This is intended to replace the use of CSS and background-image
to handle those buttons with an icon.

https://gitlab.gnome.org/GNOME/gnome-shell/issues/2214

diff --git a/js/ui/keyboard.js b/js/ui/keyboard.js
index 15d92c5924211548c3049c1ba16f8dc1fb5b1a82..a4a4f2fa2f5337c4e582b915855fcbe15ca457f5 100644 (file)
--- a/js/ui/keyboard.js
+++ b/js/ui/keyboard.js
@@ -257,11 +257,11 @@ var Key = GObject.registerClass({
         'released': { param_types: [GObject.TYPE_UINT, GObject.TYPE_STRING] },
     },
 }, class Key extends St.BoxLayout {
-    _init(key, extendedKeys) {
+    _init(key, extendedKeys, icon = null) {
         super._init({ style_class: 'key-container' });
 
         this.key = key || "";
-        this.keyButton = this._makeKey(this.key);
+        this.keyButton = this._makeKey(this.key, icon);
 
         /* Add the key in a container, so keys can be padded without losing
          * logical proportions between those.
@@ -404,14 +404,21 @@ var Key = GObject.registerClass({
         this._capturedPress = false;
     }
 
-    _makeKey(key) {
-        let label = GLib.markup_escape_text(key, -1);
+    _makeKey(key, icon) {
         let button = new St.Button({
-            label,
             style_class: 'keyboard-key',
             x_expand: true,
         });
 
+        if (icon) {
+            let child = new St.Icon({ icon_name: icon });
+            button.set_child(child);
+            this._icon = child;
+        } else {
+            let label = GLib.markup_escape_text(key, -1);
+            button.set_label(label);
+        }
+
         button.keyWidth = 1;
         button.connect('button-press-event', () => {
             this._press(key);
@@ -475,10 +482,16 @@ var Key = GObject.registerClass({
     }
 
     setLatched(latched) {
-        if (latched)
+        if (!this._icon)
+            return;
+
+        if (latched) {
             this.keyButton.add_style_pseudo_class('latched');
-        else
+            this._icon.icon_name = 'keyboard-caps-lock-filled-symbolic';
+        } else {
             this.keyButton.remove_style_pseudo_class('latched');
+            this._icon.icon_name = 'keyboard-shift-filled-symbolic';
+        }
     }
 });
 
@@ -1435,12 +1448,13 @@ class Keyboard extends St.BoxLayout {
             let keyval = key.keyval;
             let switchToLevel = key.level;
             let action = key.action;
+            let icon = key.icon;
 
             /* Skip emoji button if necessary */
             if (!this._emojiKeyVisible && action == 'emoji')
                 continue;
 
-            extraButton = new Key(key.label || '', []);
+            extraButton = new Key(key.label || '', [], icon);
 
             extraButton.keyButton.add_style_class_name('default-key');
             if (key.extraClassName != null)