wallpaper: the engine's settings page

A page for the wallpaper engine: the on switch, the interval in
minutes, a Next button, and each screen's hearted list with a remove
control and a dim for files the gallery's scan did not find. The module
reads WallEngine.on itself, because a singleton is built on first use
and the timer has to run from session start, page opened or not.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

3 files changed, 179 insertions, 0 deletions

diff --git a/desktop/modules/appearance/WallEngineModule.qml b/desktop/modules/appearance/WallEngineModule.qml
new file mode 100644
index 0000000..8357e93
--- /dev/null
+++ b/desktop/modules/appearance/WallEngineModule.qml
@@ -0,0 +1,36 @@
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+import QtQuick
+import "../.."
+
+// The wallpaper engine's page: on or off, the interval, and the two lists.
+Module {
+    name: "wallengine"
+    label: "Wallpaper engine"
+    // nf-fa-shuffle, present in Inconsolata Nerd Font.
+    icon: ""
+    settings: true
+    group: "Appearance"
+    keywords: ["wallpaper", "timer", "rotate", "rotation", "shuffle", "slideshow", "heart"]
+
+    // A singleton is built on first use, and the engine's timer has to run
+    // from the start of the session, page opened or not. Modules exist for
+    // the whole session, so this reference is what starts it.
+    readonly property bool engineOn: WallEngine.on
+
+    page: Component {
+        Page {
+            title: "Wallpaper engine"
+            WallEngineTab { width: parent.width }
+        }
+    }
+}
diff --git a/desktop/modules/appearance/WallEngineTab.qml b/desktop/modules/appearance/WallEngineTab.qml
new file mode 100644
index 0000000..dff9386
--- /dev/null
+++ b/desktop/modules/appearance/WallEngineTab.qml
@@ -0,0 +1,142 @@
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+import QtQuick
+import "../.."
+
+Item {
+    implicitHeight: col.implicitHeight
+
+    Column {
+        id: col
+        width: parent.width
+        spacing: 14
+
+        Row {
+            spacing: 8
+            Toggle {
+                anchors.verticalCenter: parent.verticalCenter
+                checked: WallEngine.on
+                label: "Change the wallpapers every"
+                onToggled: WallEngine.setOn(checked)
+            }
+            Field {
+                anchors.verticalCenter: parent.verticalCenter
+                width: 50
+                value: String(WallEngine.cfg.minutes)
+                onEdited: {
+                    WallEngine.setMinutes(Number(value));
+                    value = String(WallEngine.cfg.minutes);
+                }
+            }
+            Text {
+                anchors.verticalCenter: parent.verticalCenter
+                text: "minutes"
+                color: Theme.subtext
+                font { family: Theme.fontFamily; pixelSize: Theme.fontSize - 4 }
+            }
+            Tab {
+                text: "Next"
+                enabled: WallEngine.on && !Wallpapers.applying
+                onClicked: if (enabled) WallEngine.next()
+            }
+        }
+
+        Text {
+            width: col.width
+            wrapMode: Text.Wrap
+            text: "Timer changes recolour the desktop and leave GRUB, the homepage and the login screen alone. "
+                + "Switching off puts back each screen's home wallpaper, the one last applied by hand, with a full run."
+            color: Theme.overlay
+            font { family: Theme.fontFamily; pixelSize: Theme.fontSize - 4 }
+        }
+
+        Repeater {
+            model: [{ which: "H", name: "Horizontal, DP-1" }, { which: "V", name: "Vertical, DP-3" }]
+
+            Column {
+                id: screen
+                required property var modelData
+                readonly property var paths: WallEngine.list(modelData.which)
+                readonly property string home: modelData.which === "V" ? WallEngine.cfg.homeV : WallEngine.cfg.homeH
+                width: col.width
+                spacing: 8
+
+                Text {
+                    text: `${screen.modelData.name}: ${screen.paths.length} hearted`
+                        + (WallEngine.on && screen.home !== "" ? `, home ${Wallpapers.label(screen.home)}` : "")
+                    color: Theme.subtext
+                    font { family: Theme.fontFamily; pixelSize: Theme.fontSize - 2 }
+                }
+
+                Text {
+                    visible: screen.paths.length === 0
+                    text: "Heart a wallpaper on the Wallpaper page, with this screen selected, to add it."
+                    color: Theme.overlay
+                    font { family: Theme.fontFamily; pixelSize: Theme.fontSize - 4 }
+                }
+
+                Flow {
+                    width: col.width
+                    spacing: 8
+
+                    Repeater {
+                        model: screen.paths
+
+                        // Dimmed when the gallery's scan did not find it: the
+                        // timer skips it.
+                        Rectangle {
+                            id: entry
+                            required property string modelData
+                            width: 192; height: 108 + 20
+                            radius: 6
+                            color: Qt.alpha(Theme.surface, 0.3)
+                            opacity: WallEngine.present(modelData) ? 1 : 0.4
+                            clip: true
+
+                            Image {
+                                id: thumb
+                                anchors { top: parent.top; left: parent.left; right: parent.right; margins: 4 }
+                                height: 100
+                                source: "file://" + entry.modelData
+                                asynchronous: true
+                                cache: false
+                                fillMode: Image.PreserveAspectCrop
+                                sourceSize.width: 192
+                            }
+                            Text {
+                                anchors { top: thumb.bottom; left: parent.left; right: parent.right; margins: 4 }
+                                elide: Text.ElideMiddle
+                                text: Wallpapers.label(entry.modelData)
+                                color: Theme.subtext
+                                font { family: Theme.fontFamily; pixelSize: Theme.fontSize - 6 }
+                            }
+                            // nf-fa-xmark: out of the list.
+                            Text {
+                                anchors { top: parent.top; right: parent.right; margins: 8 }
+                                text: ""
+                                color: Theme.text
+                                style: Text.Outline
+                                styleColor: Qt.alpha(Theme.base, 0.6)
+                                font { family: Theme.iconFamily; pixelSize: Theme.fontSize }
+                                MouseArea {
+                                    anchors { fill: parent; margins: -4 }
+                                    cursorShape: Qt.PointingHandCursor
+                                    onClicked: WallEngine.toggle(entry.modelData, screen.modelData.which)
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/desktop/shell.qml b/desktop/shell.qml
index 4444cd1..d1dc7dc 100644
--- a/desktop/shell.qml
+++ b/desktop/shell.qml
@@ -85,6 +85,7 @@ ShellRoot {
             UserModule {},
             NotesModule {},
             WallpaperModule {},
+            WallEngineModule {},
             ThemeModule {},
             UdtModule {},
             IconsModule {},