Allow specifying explicit desired screen

If the window position is not specified, which is a reasonable thing to
do when using the layer shell protocol, setWidth() and setHeight() can
unintentionally change the screen() to the wrong one.

This change adds a setDesiredScreen() function so it's harder to shoot
yourself in the foot while using the layer shell protocol.

CMakeLists.txt

@@ -4,7 +4,7 @@
 cmake_minimum_required(VERSION 3.16)
 
 project(layershellqt)
-set(PROJECT_VERSION "6.4.90")
+set(PROJECT_VERSION "6.5.80")
 set(PROJECT_VERSION_MAJOR 6)
 
 set(CMAKE_C_STANDARD 99)

src/declarative/CMakeLists.txt

@@ -4,7 +4,7 @@
 ecm_add_qml_module(LayerShellQtQml
                   URI "org.kde.layershell"
                   VERSION 1.0
-                  SOURCES types.h types.cpp
+                  SOURCES types.h
                   GENERATE_PLUGIN_SOURCE)
 target_link_libraries(LayerShellQtQml PRIVATE Qt::Qml LayerShellQtInterface)
 

src/declarative/types.cpp

@@ -1,49 +0,0 @@
-/*
- *   SPDX-FileCopyrightText: 2023 Aleix Pol Gonzalez <aleix.pol_gonzalez@mercedes-benz.com>
- *
- *   SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
- */
-
-#include "types.h"
-
-#if QT_VERSION < QT_VERSION_CHECK(6, 8, 1)
-int QQmlMarginsValueType::left() const
-{
-    return m.left();
-}
-
-int QQmlMarginsValueType::top() const
-{
-    return m.top();
-}
-
-int QQmlMarginsValueType::right() const
-{
-    return m.right();
-}
-
-int QQmlMarginsValueType::bottom() const
-{
-    return m.bottom();
-}
-
-void QQmlMarginsValueType::setLeft(int left)
-{
-    m.setLeft(left);
-}
-
-void QQmlMarginsValueType::setTop(int top)
-{
-    m.setTop(top);
-}
-
-void QQmlMarginsValueType::setRight(int right)
-{
-    m.setRight(right);
-}
-
-void QQmlMarginsValueType::setBottom(int bottom)
-{
-    m.setBottom(bottom);
-}
-#endif

src/declarative/types.h

@@ -17,39 +17,3 @@ class WindowForeign
     QML_UNCREATABLE("")
     QML_ATTACHED(LayerShellQt::Window)
 };
-
-// available upstream since https://invent.kde.org/qt/qt/qtdeclarative/-/commit/a398101f715bfc447aa889fc9c58b13bfe75ab47
-#if QT_VERSION < QT_VERSION_CHECK(6, 8, 1)
-struct Q_QML_EXPORT QQmlMarginsValueType {
-    QMargins m;
-    Q_PROPERTY(int left READ left WRITE setLeft FINAL)
-    Q_PROPERTY(int right READ right WRITE setRight FINAL)
-    Q_PROPERTY(int top READ top WRITE setTop FINAL)
-    Q_PROPERTY(int bottom READ bottom WRITE setBottom FINAL)
-    Q_GADGET
-    QML_ANONYMOUS
-    QML_FOREIGN(QMargins)
-    QML_EXTENDED(QQmlMarginsValueType)
-    QML_STRUCTURED_VALUE
-
-public:
-    QQmlMarginsValueType() = default;
-    Q_INVOKABLE QQmlMarginsValueType(const QMarginsF &margins)
-        : m(margins.toMargins())
-    {
-    }
-    int left() const;
-    int right() const;
-    int top() const;
-    int bottom() const;
-    void setLeft(int);
-    void setRight(int);
-    void setTop(int);
-    void setBottom(int);
-
-    operator QMargins() const
-    {
-        return m;
-    }
-};
-#endif

src/interfaces/window.cpp

@@ -9,6 +9,7 @@
 
 #include <layershellqt_logging.h>
 
+#include <QPlatformSurfaceEvent>
 #include <QPointer>
 #include <optional>
 
@@ -33,7 +34,8 @@ public:
     Window::Layer layer = Window::LayerTop;
     QMargins margins;
     QSize desiredSize = QSize(0, 0);
-    Window::ScreenConfiguration screenConfiguration = Window::ScreenFromQWindow;
+    QPointer<QScreen> desiredScreen;
+    bool desiredActiveScreen = false;
     bool closeOnDismissed = true;
     bool activateOnShow = true;
 };
@@ -151,14 +153,46 @@ Window::Layer Window::layer() const
     return d->layer;
 }
 
-Window::ScreenConfiguration Window::screenConfiguration() const
+void Window::setDesiredActiveScreen(bool set)
 {
-    return d->screenConfiguration;
+    if (d->desiredActiveScreen == set) {
+        return;
+    }
+
+    d->desiredActiveScreen = set;
+
+    if (d->desiredActiveScreen && d->desiredScreen) {
+        d->desiredScreen = nullptr;
+        Q_EMIT desiredScreenChanged();
+    }
+
+    Q_EMIT desiredActiveScreenChanged();
 }
 
-void Window::setScreenConfiguration(Window::ScreenConfiguration screenConfiguration)
+bool Window::desiredActiveScreen() const
 {
-    d->screenConfiguration = screenConfiguration;
+    return d->desiredActiveScreen;
+}
+
+void Window::setDesiredScreen(QScreen *screen)
+{
+    if (d->desiredScreen == screen) {
+        return;
+    }
+
+    d->desiredScreen = screen;
+
+    if (d->desiredScreen && d->desiredActiveScreen) {
+        d->desiredActiveScreen = false;
+        Q_EMIT desiredActiveScreenChanged();
+    }
+
+    Q_EMIT desiredScreenChanged();
+}
+
+QScreen *Window::desiredScreen() const
+{
+    return d->desiredScreen;
 }
 
 bool Window::closeOnDismissed() const
@@ -186,12 +220,35 @@ Window::Window(QWindow *window)
     , d(new WindowPrivate(window))
 {
     s_map.insert(d->parentWindow, this);
+    window->installEventFilter(this);
+    if (window->isVisible()) {
+        qCWarning(LAYERSHELLQT) << d->parentWindow << "already has a shell integration. Call QWindow::close() first and show it again.";
+    }
 
-    window->create();
+    if (window->handle()) {
+        initializeShell();
+    }
+}
 
-    auto waylandWindow = dynamic_cast<QtWaylandClient::QWaylandWindow *>(window->handle());
+bool Window::eventFilter(QObject *watched, QEvent *event)
+{
+    auto window = qobject_cast<QWindow *>(watched);
+    if (!window) {
+        return false;
+    }
+    if (event->type() == QEvent::PlatformSurface) {
+        if (auto pse = static_cast<QPlatformSurfaceEvent *>(event); pse->surfaceEventType() == QPlatformSurfaceEvent::SurfaceCreated) {
+            initializeShell();
+        }
+    }
+    return false;
+}
+
+void Window::initializeShell()
+{
+    auto waylandWindow = dynamic_cast<QtWaylandClient::QWaylandWindow *>(d->parentWindow->handle());
     if (!waylandWindow) {
-        qCWarning(LAYERSHELLQT) << window << "is not a wayland window. Not creating zwlr_layer_surface";
+        qCWarning(LAYERSHELLQT) << d->parentWindow << "is not a wayland window. Not creating zwlr_layer_surface";
         return;
     }
 
@@ -205,7 +262,6 @@ Window::Window(QWindow *window)
             return;
         }
     }
-
     waylandWindow->setShellIntegration(shellIntegration);
 }
 

src/interfaces/window.h

@@ -27,8 +27,9 @@ class LAYERSHELLQT_EXPORT Window : public QObject
     Q_PROPERTY(qint32 exclusionZone READ exclusionZone WRITE setExclusiveZone NOTIFY exclusionZoneChanged)
     Q_PROPERTY(Layer layer READ layer WRITE setLayer NOTIFY layerChanged)
     Q_PROPERTY(KeyboardInteractivity keyboardInteractivity READ keyboardInteractivity WRITE setKeyboardInteractivity NOTIFY keyboardInteractivityChanged)
-    Q_PROPERTY(ScreenConfiguration screenConfiguration READ screenConfiguration WRITE setScreenConfiguration)
     Q_PROPERTY(bool activateOnShow READ activateOnShow WRITE setActivateOnShow)
+    Q_PROPERTY(bool desiredActiveScreen READ desiredActiveScreen WRITE setDesiredActiveScreen NOTIFY desiredActiveScreenChanged)
+    Q_PROPERTY(QScreen *desiredScreen READ desiredScreen WRITE setDesiredScreen NOTIFY desiredScreenChanged)
 
 public:
     ~Window() override;
@@ -64,17 +65,6 @@ public:
     };
     Q_ENUM(KeyboardInteractivity)
 
-    /**
-     * This enum type is used to specify which screen to place the surface on.
-     * ScreenFromQWindow (the default) reads QWindow::screen() while ScreenFromCompositor
-     * passes nil and lets the compositor decide.
-     */
-    enum ScreenConfiguration {
-        ScreenFromQWindow = 0,
-        ScreenFromCompositor = 1,
-    };
-    Q_ENUM(ScreenConfiguration)
-
     void setAnchors(Anchors anchor);
     Anchors anchors() const;
 
@@ -96,8 +86,33 @@ public:
     void setLayer(Layer layer);
     Layer layer() const;
 
-    void setScreenConfiguration(ScreenConfiguration screenConfiguration);
-    ScreenConfiguration screenConfiguration() const;
+    /**
+     * Indicates whether the layer shell surface should be placed on the active screen based on @a set.
+     *
+     * The active screen depends on the compositor policies.
+     *
+     * If no explicit desired screen has been specified with the setDesiredScreen() function or the layer
+     * surface doesn't need to be placed on the active screen, i.e. setDesiredActiveScreen() has not
+     * been called, the QWindow::screen() will be used to decide what screen the layer shell surface
+     * should be placed on.
+     *
+     * The desiredScreen() will be reset if @a set is @c true.
+     */
+    void setDesiredActiveScreen(bool set);
+    bool desiredActiveScreen() const;
+
+    /**
+     * Indicates that the layer shell surface should be placed on the specified @a screen.
+     *
+     * If no explicit desired screen has been specified with the setDesiredScreen() function or the layer
+     * surface doesn't need to be placed on the active screen, i.e. setDesiredActiveScreen() has not
+     * been called, the QWindow::screen() will be used to decide what screen the layer shell surface
+     * should be placed on.
+     *
+     * The desiredActiveScreen() will be reset to @c false after calling this function.
+     */
+    void setDesiredScreen(QScreen *screen);
+    QScreen *desiredScreen() const;
 
     /**
      * Sets a string based identifier for this window.
@@ -138,6 +153,8 @@ public:
 
     static Window *qmlAttachedProperties(QObject *object);
 
+    bool eventFilter(QObject *watched, QEvent *event) override;
+
 Q_SIGNALS:
     void anchorsChanged();
     void exclusionZoneChanged();
@@ -146,8 +163,12 @@ Q_SIGNALS:
     void desiredSizeChanged();
     void keyboardInteractivityChanged();
     void layerChanged();
+    void desiredActiveScreenChanged();
+    void desiredScreenChanged();
 
 private:
+    void initializeShell();
+
     Window(QWindow *window);
     QScopedPointer<WindowPrivate> d;
 };

src/qwaylandlayersurface.cpp

@@ -26,7 +26,12 @@ QWaylandLayerSurface::QWaylandLayerSurface(QWaylandLayerShellIntegration *shell,
     , m_window(window)
 {
     wl_output *output = nullptr;
-    if (m_interface->screenConfiguration() == Window::ScreenFromQWindow) {
+    if (!m_interface->desiredActiveScreen()) {
+        QScreen *desiredScreen = m_interface->desiredScreen();
+        if (!desiredScreen) {
+            window->window()->screen();
+        }
+
         auto waylandScreen = dynamic_cast<QtWaylandClient::QWaylandScreen *>(window->window()->screen()->handle());
         // Qt will always assign a screen to a window, but if the compositor has no screens available a dummy QScreen object is created
         // this will not cast to a QWaylandScreen
@@ -124,13 +129,7 @@ void QWaylandLayerSurface::attachPopup(QtWaylandClient::QWaylandShellSurface *po
 
 void QWaylandLayerSurface::applyConfigure()
 {
-#if QT_VERSION < QT_VERSION_CHECK(6, 9, 0)
-    m_configuring = true;
-#endif
     window()->resizeFromApplyConfigure(m_pendingSize);
-#if QT_VERSION < QT_VERSION_CHECK(6, 9, 0)
-    m_configuring = false;
-#endif
 }
 
 void QWaylandLayerSurface::setDesiredSize(const QSize &size)
@@ -181,25 +180,12 @@ void QWaylandLayerSurface::setLayer(uint32_t layer)
         set_layer(layer);
 }
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 9, 0)
-void QWaylandLayerSurface::setWindowGeometry(const QRect &geometry)
-{
-    if (m_configuring) {
-        return;
-    }
-
-    if (m_interface->desiredSize().isNull()) {
-        setDesiredSize(geometry.size());
-    }
-}
-#else
 void QWaylandLayerSurface::setWindowSize(const QSize &size)
 {
     if (m_interface->desiredSize().isNull()) {
         setDesiredSize(size);
     }
 }
-#endif
 
 bool QWaylandLayerSurface::requestActivate()
 {
@@ -268,13 +254,6 @@ void QWaylandLayerSurface::requestXdgActivationToken(quint32 serial)
 
 void QWaylandLayerSurface::sendExpose()
 {
-#if QT_VERSION < QT_VERSION_CHECK(6, 7, 0)
-    window()->handleExpose(QRect(QPoint(), m_pendingSize));
-#elif QT_VERSION < QT_VERSION_CHECK(6, 9, 0)
-    window()->sendRecursiveExposeEvent();
-#else
     window()->updateExposure();
-#endif
 }
-
 }

src/qwaylandlayersurface_p.h

@@ -43,11 +43,7 @@ public:
     void setLayer(uint32_t layer);
 
     void applyConfigure() override;
-#if QT_VERSION < QT_VERSION_CHECK(6, 9, 0)
-    void setWindowGeometry(const QRect &geometry) override;
-#else
     void setWindowSize(const QSize &size) override;
-#endif
 
     bool requestActivate() override;
     bool requestActivateOnShow() override;
@@ -66,9 +62,6 @@ private:
     QString m_activationToken;
 
     bool m_configured = false;
-#if QT_VERSION < QT_VERSION_CHECK(6, 9, 0)
-    bool m_configuring = false;
-#endif
 };
 
 }

tests/become-layershell.qml

@@ -0,0 +1,42 @@
+/*
+ *   SPDX-FileCopyrightText: 2025 Aleix Pol i Gonzalez <aleixpol@kde.org>
+ *
+ *   SPDX-License-Identifier: LGPL-3.0-or-later
+ */
+
+import QtQuick
+import QtQuick.Controls
+import org.kde.layershell 1.0 as LayerShell
+
+Item
+{
+    Button {
+        text: "Convert"
+        anchors.centerIn: parent
+
+        onClicked: {
+            win.close()
+            win.LayerShell.Window.anchors = LayerShell.Window.AnchorLeft;
+            win.LayerShell.Window.layer = LayerShell.Window.LayerTop;
+            win.LayerShell.Window.exclusionZone = -1;
+            win.show()
+        }
+    }
+
+    Window {
+        id: win
+
+        width: 100
+        height: 100
+        Rectangle {
+            anchors.fill: parent
+            color: "red"
+
+            Text {
+                anchors.centerIn: parent
+                text: "top"
+            }
+        }
+        visible: true
+    }
+}