Revamp pure-qml example

- Use a ListModel to manage shellSurfaces
- Remove obsolete/deprecated extensions (QtWindowManager, XdgShellV5)
- Remove no-ops (onSurfaceRequested created a default surface)
- Remove dead code (primarySurfaceArea, output property on Window)
- Add comments
- Follow coding conventions (formatting, order of object attributes etc.)

Task-number: QTBUG-60661
Change-Id: I4ffd2c4b5deff1d801a25efa96300fc5851d3359
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

4 files changed, 62 insertions, 70 deletions

diff --git a/examples/wayland/pure-qml/qml/Chrome.qml b/examples/wayland/pure-qml/qml/Chrome.qml
index 2e2586c1b..a63ee705c 100644
--- a/examples/wayland/pure-qml/qml/Chrome.qml
+++ b/examples/wayland/pure-qml/qml/Chrome.qml
@@ -52,16 +52,28 @@ import QtQuick 2.0
 import QtWayland.Compositor 1.0
 
 ShellSurfaceItem {
-    id: rootChrome
-    autoCreatePopupItems: true
+    id: chrome
 
     property bool isChild: parent.shellSurface !== undefined
 
+    signal destroyAnimationFinished
+
+    // If the client asks to show popups on this surface, automatically create child ShellSurfaceItems
+    autoCreatePopupItems: true
+
     onSurfaceDestroyed: {
         bufferLocked = true;
         destroyAnimation.start();
     }
 
+    transform: [
+        Scale {
+            id: scaleTransform
+            origin.x: chrome.width / 2
+            origin.y: chrome.height / 2
+        }
+    ]
+
     Connections {
         target: shellSurface
 
@@ -77,17 +89,19 @@ ShellSurfaceItem {
 
     SequentialAnimation {
         id: destroyAnimation
+
         ParallelAnimation {
             NumberAnimation { target: scaleTransform; property: "yScale"; to: 2/height; duration: 150 }
             NumberAnimation { target: scaleTransform; property: "xScale"; to: 0.4; duration: 150 }
-            NumberAnimation { target: rootChrome; property: "opacity"; to: rootChrome.isChild ? 0 : 1; duration: 150 }
+            NumberAnimation { target: chrome; property: "opacity"; to: chrome.isChild ? 0 : 1; duration: 150 }
         }
         NumberAnimation { target: scaleTransform; property: "xScale"; to: 0; duration: 150 }
-        ScriptAction { script: { rootChrome.destroy(); } }
+        ScriptAction { script: destroyAnimationFinished() }
     }
 
     SequentialAnimation {
         id: receivedFocusAnimation
+
         ParallelAnimation {
             NumberAnimation { target: scaleTransform; property: "yScale"; to: 1.02; duration: 100; easing.type: Easing.OutQuad }
             NumberAnimation { target: scaleTransform; property: "xScale"; to: 1.02; duration: 100; easing.type: Easing.OutQuad }
@@ -97,12 +111,4 @@ ShellSurfaceItem {
             NumberAnimation { target: scaleTransform; property: "xScale"; to: 1; duration: 100; easing.type: Easing.InOutQuad }
         }
     }
-
-    transform: [
-        Scale {
-            id:scaleTransform
-            origin.x: rootChrome.width / 2
-            origin.y: rootChrome.height / 2
-        }
-    ]
 }
diff --git a/examples/wayland/pure-qml/qml/Keyboard.qml b/examples/wayland/pure-qml/qml/Keyboard.qml
index e1f0a8b19..b2586ffd4 100644
--- a/examples/wayland/pure-qml/qml/Keyboard.qml
+++ b/examples/wayland/pure-qml/qml/Keyboard.qml
@@ -52,9 +52,8 @@ import QtQuick 2.5
 import QtQuick.VirtualKeyboard 2.1
 
 InputPanel {
-    id: inputPanel
     visible: active
-    y: active ? parent.height - inputPanel.height : parent.height
+    y: active ? parent.height - height : parent.height
     anchors.left: parent.left
     anchors.right: parent.right
 }
diff --git a/examples/wayland/pure-qml/qml/Screen.qml b/examples/wayland/pure-qml/qml/Screen.qml
index 562eb86c5..b156cb434 100644
--- a/examples/wayland/pure-qml/qml/Screen.qml
+++ b/examples/wayland/pure-qml/qml/Screen.qml
@@ -54,49 +54,69 @@ import QtWayland.Compositor 1.0
 
 WaylandOutput {
     id: output
-    property alias surfaceArea: background
-    sizeFollowsWindow: true
-    window: Window {
-        id: screen
 
-        property QtObject output
+    property ListModel shellSurfaces: ListModel {}
+    property bool isNestedCompositor: Qt.platform.pluginName.startsWith("wayland") || Qt.platform.pluginName === "xcb"
+
+    function handleShellSurface(shellSurface) {
+        shellSurfaces.append({shellSurface: shellSurface});
+    }
+
+    // During development, it can be useful to start the compositor inside X11 or
+    // another Wayland compositor. In such cases, set sizeFollowsWindow to true to
+    // enable resizing of the compositor window to be forwarded to the Wayland clients
+    // as the output (screen) changing resolution. Consider setting it to false if you
+    // are running the compositor using eglfs, linuxfb or similar QPA backends.
+    sizeFollowsWindow: output.isNestedCompositor
 
+    window: Window {
         width: 1024
         height: 760
         visible: true
 
         WaylandMouseTracker {
             id: mouseTracker
+
             anchors.fill: parent
 
-            windowSystemCursorEnabled: true
+            // Set this to false to disable the outer mouse cursor when running nested
+            // compositors. Otherwise you would see two mouse cursors, one for each compositor.
+            windowSystemCursorEnabled: output.isNestedCompositor
+
             Image {
                 id: background
+
                 anchors.fill: parent
                 fillMode: Image.Tile
                 source: "qrc:/images/background.jpg"
                 smooth: true
+
+                Repeater {
+                    model: output.shellSurfaces
+                    // Chrome displays a shell surface on the screen (See Chrome.qml)
+                    Chrome {
+                        shellSurface: modelData
+                        onDestroyAnimationFinished: output.shellSurfaces.remove(index)
+                    }
+                }
             }
+
+            // Virtual Keyboard
             Loader {
                 anchors.fill: parent
                 source: "Keyboard.qml"
             }
+
+            // Draws the mouse cursor for a given Wayland seat
             WaylandCursorItem {
-                id: cursor
                 inputEventsEnabled: false
                 x: mouseTracker.mouseX
                 y: mouseTracker.mouseY
-
                 seat: output.compositor.defaultSeat
             }
         }
 
         Shortcut {
-            sequence: "Meta+F"
-            onActivated: qtWindowManager.showIsFullScreen = !qtWindowManager.showIsFullScreen
-        }
-
-        Shortcut {
             sequence: "Ctrl+Alt+Backspace"
             onActivated: Qt.quit()
         }
diff --git a/examples/wayland/pure-qml/qml/main.qml b/examples/wayland/pure-qml/qml/main.qml
index 7bf2a623c..b188ebbb5 100644
--- a/examples/wayland/pure-qml/qml/main.qml
+++ b/examples/wayland/pure-qml/qml/main.qml
@@ -52,54 +52,21 @@ import QtQuick 2.0
 import QtWayland.Compositor 1.1
 
 WaylandCompositor {
-    id: comp
+    id: waylandCompositor
 
-    property var primarySurfacesArea: null
-
-    Screen {
-        compositor: comp
-    }
-
-    Component {
-        id: chromeComponent
-        Chrome {
-        }
-    }
-
-    Component {
-        id: surfaceComponent
-        WaylandSurface {
-        }
-    }
-
-    QtWindowManager {
-        id: qtWindowManager
-        onShowIsFullScreenChanged: console.debug("Show is fullscreen hint for Qt applications:", showIsFullScreen)
-    }
-
-    WlShell {
-        onWlShellSurfaceCreated: {
-            chromeComponent.createObject(defaultOutput.surfaceArea, { "shellSurface": shellSurface } );
-        }
-    }
-
-    XdgShellV5 {
-        onXdgSurfaceCreated: {
-            chromeComponent.createObject(defaultOutput.surfaceArea, { "shellSurface": xdgSurface } );
-        }
-    }
+    Screen { id: screen; compositor: waylandCompositor }
 
+    // Shell surface extension. Needed to provide a window concept for Wayland clients.
+    // I.e. requests and events for maximization, minimization, resizing, closing etc.
     XdgShellV6 {
-        onToplevelCreated: {
-            chromeComponent.createObject(defaultOutput.surfaceArea, { "shellSurface": xdgSurface } );
-        }
+        onToplevelCreated: screen.handleShellSurface(xdgSurface)
     }
 
-    TextInputManager {
+    // Deprecated shell extension, still used by some clients
+    WlShell {
+        onWlShellSurfaceCreated: screen.handleShellSurface(shellSurface)
     }
 
-    onSurfaceRequested: {
-        var surface = surfaceComponent.createObject(comp, { } );
-        surface.initialize(comp, client, id, version);
-    }
+    // Extension for Virtual keyboard support
+    TextInputManager {}
 }