[gnome-shell/gbsneto/new-lock-screen-part2: 1/5] unlockDialog: Create auth prompt on demand

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 85fefd1c9c103bfadd887cb6206275a764ba96d4
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon Dec 2 11:01:20 2019 -0300

    unlockDialog: Create auth prompt on demand
    
    AuthPrompt is the set of actors that contain the user avatar,
    the username, and the password entry. With the removal of the
    screen shield, the unlock dialog (be it UnlockDialog or the
    LoginDialog) is always created, and in the case of UnlockDialog,
    so is the auth prompt.
    
    This is problematic, though, since for passwordless accounts,
    the simple act of creating AuthPrompt authenticates the user,
    and lifts the lock screen.
    
    Create the AuthPrompt on demand in UnlockDialog.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/872

 js/ui/unlockDialog.js | 90 +++++++++++++++++++++++++++++++++++----------------
 1 file changed, 62 insertions(+), 28 deletions(-)
---
diff --git a/js/ui/unlockDialog.js b/js/ui/unlockDialog.js
index ec08acd1cf..9b8cfd9352 100644
--- a/js/ui/unlockDialog.js
+++ b/js/ui/unlockDialog.js
@@ -453,34 +453,9 @@ var UnlockDialog = GObject.registerClass({
         stack.add_child(this._clock);
         this._showClock();
 
-        this._authPrompt = new AuthPrompt.AuthPrompt(new Gdm.Client(), 
AuthPrompt.AuthPromptMode.UNLOCK_ONLY);
-        this._authPrompt.connect('failed', this._fail.bind(this));
-        this._authPrompt.connect('cancelled', this._fail.bind(this));
-        this._authPrompt.connect('reset', this._onReset.bind(this));
-        this._authPrompt.nextButton.label = _("Unlock");
-
-        this._promptBox.add_child(this._authPrompt);
-
         this.allowCancel = false;
 
-        let screenSaverSettings = new Gio.Settings({ schema_id: 'org.gnome.desktop.screensaver' });
-        if (screenSaverSettings.get_boolean('user-switch-enabled')) {
-            let otherUserLabel = new St.Label({ text: _("Log in as another user"),
-                                                style_class: 'login-dialog-not-listed-label' });
-            this._otherUserButton = new St.Button({ style_class: 'login-dialog-not-listed-button',
-                                                    can_focus: true,
-                                                    child: otherUserLabel,
-                                                    reactive: true });
-            this._otherUserButton.connect('clicked', this._otherUserClicked.bind(this));
-            this._promptBox.add_child(this._otherUserButton);
-        } else {
-            this._otherUserButton = null;
-        }
-
-        this._authPrompt.reset();
-        this._updateSensitivity(true);
-
-        Main.ctrlAltTabManager.addGroup(this, _("Unlock Window"), 'dialog-password-symbolic');
+        Main.ctrlAltTabManager.addGroup(this, _('Unlock Window'), 'dialog-password-symbolic');
 
         // Notifications
         this._notificationsBox = new NotificationsBox();
@@ -555,6 +530,58 @@ var UnlockDialog = GObject.registerClass({
             this._createBackground(i);
     }
 
+    _ensureAuthPrompt() {
+        if (this._authPrompt)
+            return;
+
+        this._authPrompt = new AuthPrompt.AuthPrompt(new Gdm.Client(), 
AuthPrompt.AuthPromptMode.UNLOCK_ONLY);
+        this._authPrompt.connect('failed', this._fail.bind(this));
+        this._authPrompt.connect('cancelled', this._fail.bind(this));
+        this._authPrompt.connect('reset', this._onReset.bind(this));
+        this._authPrompt.nextButton.label = _("Unlock");
+
+        this._promptBox.add_child(this._authPrompt);
+
+        let screenSaverSettings = new Gio.Settings({ schema_id: 'org.gnome.desktop.screensaver' });
+        if (screenSaverSettings.get_boolean('user-switch-enabled')) {
+            let otherUserLabel = new St.Label({
+                text: _('Log in as another user'),
+                style_class: 'login-dialog-not-listed-label',
+            });
+            this._otherUserButton = new St.Button({
+                style_class: 'login-dialog-not-listed-button',
+                can_focus: true,
+                child: otherUserLabel,
+                reactive: true,
+            });
+            this._otherUserButton.connect('clicked', this._otherUserClicked.bind(this));
+            this._promptBox.add_child(this._otherUserButton);
+        } else {
+            this._otherUserButton = null;
+        }
+
+        this._authPrompt.reset();
+        this._updateSensitivity(true);
+    }
+
+    _maybeDestroyAuthPrompt() {
+        let focus = global.stage.key_focus;
+        if (focus === null ||
+            (this._authPrompt && this._authPrompt.contains(focus)) ||
+            (this._otherUserButton && focus === this._otherUserButton))
+            this.grab_key_focus();
+
+        if (this._authPrompt) {
+            this._authPrompt.destroy();
+            this._authPrompt = null;
+        }
+
+        if (this._otherUserButton) {
+            this._otherUserButton.destroy();
+            this._otherUserButton = null;
+        }
+    }
+
     _updateSensitivity(sensitive) {
         this._authPrompt.updateSensitivity(sensitive);
 
@@ -575,7 +602,10 @@ var UnlockDialog = GObject.registerClass({
             opacity: 0,
             duration: CROSSFADE_TIME,
             mode: Clutter.AnimationMode.EASE_OUT_QUAD,
-            onComplete: () => this._promptBox.hide(),
+            onComplete: () => {
+                this._promptBox.hide();
+                this._maybeDestroyAuthPrompt();
+            },
         });
 
         this._clock.ease({
@@ -586,6 +616,8 @@ var UnlockDialog = GObject.registerClass({
     }
 
     _showPrompt() {
+        this._ensureAuthPrompt();
+
         if (this._activePage === this._promptBox)
             return;
 
@@ -649,7 +681,8 @@ var UnlockDialog = GObject.registerClass({
     }
 
     cancel() {
-        this._authPrompt.cancel();
+        if (this._authPrompt)
+            this._authPrompt.cancel();
     }
 
     addCharacter(unichar) {
@@ -658,6 +691,7 @@ var UnlockDialog = GObject.registerClass({
     }
 
     finish(onComplete) {
+        this._ensureAuthPrompt();
         this._authPrompt.finish(onComplete);
     }