Add an explicit unlock button for passwordless users

In the refactor we correctly made it so passwordless users were not
prompted for passwords.

This is in the right direction but the UX was still slightly off as it
meant wiggling the mouse unlocked the screen, not an explicit action.

This patch adds an explicit button that must be pressed if no other
prompts were given during the authentication process.

BUG: 440055

lookandfeel/contents/lockscreen/LockScreenUi.qml

@@ -24,6 +24,7 @@ PlasmaCore.ColorScope {
     // If we're using software rendering, draw outlines instead of shadows
     // See https://bugs.kde.org/show_bug.cgi?id=398317
     readonly property bool softwareRendering: GraphicsInfo.api === GraphicsInfo.Software
+    property bool hadPrompt: false;
 
     colorGroup: PlasmaCore.Theme.ComplementaryColorGroup
 
@@ -40,7 +41,13 @@ PlasmaCore.ColorScope {
         }
 
         function onSucceeded() {
-            Qt.quit();
+            if (lockScreenUi.hadPrompt) {
+                Qt.quit();
+            } else {
+                mainStack.push(Qt.resolvedUrl("NoPasswordUnlock.qml"),
+                               {"userListModel": users});
+                mainStack.forceActiveFocus();
+            }
         }
 
         function onInfoMessage(msg) {
@@ -58,12 +65,14 @@ PlasmaCore.ColorScope {
         }
 
         function onPrompt(msg) {
+            lockScreenUi.hadPrompt = true;
             root.notification = msg;
             mainBlock.echoMode = TextInput.Normal
             mainBlock.mainPasswordBox.text = "";
             mainBlock.mainPasswordBox.forceActiveFocus();
         }
         function onPromptForSecret(msg) {
+            lockScreenUi.hadPrompt = true;
             mainBlock.echoMode = TextInput.Password
             mainBlock.mainPasswordBox.text = "";
             mainBlock.mainPasswordBox.forceActiveFocus();

lookandfeel/contents/lockscreen/NoPasswordUnlock.qml

@@ -0,0 +1,23 @@
+/*
+    SPDX-FileCopyrightText: 2022 David Edmundson <davidedmundson@kde.org>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+import QtQuick 2.2
+
+import org.kde.plasma.components 3.0 as PlasmaComponents3
+
+import "../components"
+
+SessionManagementScreen {
+        focus: true
+        PlasmaComponents3.Button {
+            id: loginButton
+            focus: true
+            text: i18nd("plasma_lookandfeel_org.kde.lookandfeel", "Unlock")
+            icon.name: LayoutMirroring.enabled ? "go-previous" : "go-next"
+            onClicked: Qt.quit();
+            Keys.onEnterPressed: clicked()
+            Keys.onReturnPressed: clicked()
+        }
+}