From daa3cda4d4831b692f504f98aa6eeddabceb64a1 Mon Sep 17 00:00:00 2001
From: Kai Uwe Broulik <kde@privat.broulik.de>
Date: Sun, 6 Apr 2025 16:51:36 +0200
Subject: [PATCH] Wayland: Set XDG dialog modal in setMainWindow when
 applicable

Before Qt 6.10, Qt's built-in XDG Dialog support only sets modal when
it has an in-process transient parent. It wouldn't know that we'll be
setting a parent through XDG Foreign afterwards.

Have setMainWindow check for Qt version and window modality and use
XDG Dialog to make the parent-child relationship modal.

BUG: 493647
---
 src/platforms/wayland/CMakeLists.txt         |  3 ++
 src/platforms/wayland/surfacehelper.h        | 15 ++++++
 src/platforms/wayland/waylandxdgdialogv1.cpp | 48 ++++++++++++++++++++
 src/platforms/wayland/waylandxdgdialogv1_p.h | 36 +++++++++++++++
 src/platforms/wayland/windowsystem.cpp       | 15 ++++++
 5 files changed, 117 insertions(+)
 create mode 100644 src/platforms/wayland/waylandxdgdialogv1.cpp
 create mode 100644 src/platforms/wayland/waylandxdgdialogv1_p.h

diff --git a/src/platforms/wayland/CMakeLists.txt b/src/platforms/wayland/CMakeLists.txt
index 545f920c..26ff123b 100644
--- a/src/platforms/wayland/CMakeLists.txt
+++ b/src/platforms/wayland/CMakeLists.txt
@@ -6,6 +6,7 @@ set(wayland_plugin_SRCS
     windowshadow.cpp
     windowsystem.cpp
     waylandxdgactivationv1.cpp
+    waylandxdgdialogv1.cpp
     waylandxdgforeignv2.cpp
     plugin.h
     windoweffects.h
@@ -23,6 +24,8 @@ qt6_generate_wayland_protocol_client_sources(KF6WindowSystemKWaylandPlugin
     FILES
         ${WaylandProtocols_DATADIR}/staging/xdg-activation/xdg-activation-v1.xml
         ${WaylandProtocols_DATADIR}/unstable/xdg-foreign/xdg-foreign-unstable-v2.xml
+        ${WaylandProtocols_DATADIR}/staging/xdg-dialog/xdg-dialog-v1.xml
+        ${WaylandProtocols_DATADIR}/stable/xdg-shell/xdg-shell.xml
         ${PLASMA_WAYLAND_PROTOCOLS_DIR}/blur.xml
         ${PLASMA_WAYLAND_PROTOCOLS_DIR}/contrast.xml
         ${PLASMA_WAYLAND_PROTOCOLS_DIR}/slide.xml
diff --git a/src/platforms/wayland/surfacehelper.h b/src/platforms/wayland/surfacehelper.h
index ba2f7cb5..3cc22e45 100644
--- a/src/platforms/wayland/surfacehelper.h
+++ b/src/platforms/wayland/surfacehelper.h
@@ -14,6 +14,7 @@
 #include <qpa/qplatformnativeinterface.h>
 
 struct wl_surface;
+struct xdg_toplevel;
 
 inline wl_surface *surfaceForWindow(QWindow *window)
 {
@@ -38,3 +39,17 @@ inline wl_surface *surfaceForWindow(QWindow *window)
 
     return reinterpret_cast<wl_surface *>(native->nativeResourceForWindow(QByteArrayLiteral("surface"), window));
 }
+
+inline xdg_toplevel *xdgToplevelForWindow(QWindow *window)
+{
+    if (!window) {
+        return nullptr;
+    }
+
+    QPlatformNativeInterface *native = qGuiApp->platformNativeInterface();
+    if (!native) {
+        return nullptr;
+    }
+
+    return reinterpret_cast<xdg_toplevel *>(native->nativeResourceForWindow(QByteArrayLiteral("xdg_toplevel"), window));
+}
diff --git a/src/platforms/wayland/waylandxdgdialogv1.cpp b/src/platforms/wayland/waylandxdgdialogv1.cpp
new file mode 100644
index 00000000..828786ab
--- /dev/null
+++ b/src/platforms/wayland/waylandxdgdialogv1.cpp
@@ -0,0 +1,48 @@
+/*
+    SPDX-FileCopyrightText: 2025 Kai Uwe Broulik <kde@broulik.de>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+#include "waylandxdgdialogv1_p.h"
+
+#include <QGuiApplication>
+
+WaylandXdgDialogV1::WaylandXdgDialogV1(::xdg_dialog_v1 *object)
+    : QObject()
+    , QtWayland::xdg_dialog_v1(object)
+{
+}
+
+WaylandXdgDialogV1::~WaylandXdgDialogV1()
+{
+    if (qGuiApp) {
+        destroy();
+    }
+}
+
+WaylandXdgDialogWmV1::WaylandXdgDialogWmV1()
+    : QWaylandClientExtensionTemplate<WaylandXdgDialogWmV1>(1)
+{
+    initialize();
+}
+
+WaylandXdgDialogWmV1::~WaylandXdgDialogWmV1()
+{
+    if (qGuiApp && isActive()) {
+        destroy();
+    }
+}
+
+WaylandXdgDialogWmV1 &WaylandXdgDialogWmV1::self()
+{
+    static WaylandXdgDialogWmV1 s_instance;
+    return s_instance;
+}
+
+WaylandXdgDialogV1 *WaylandXdgDialogWmV1::getDialog(struct ::xdg_toplevel *toplevel)
+{
+    return new WaylandXdgDialogV1(get_xdg_dialog(toplevel));
+}
+
+#include "moc_waylandxdgdialogv1_p.cpp"
diff --git a/src/platforms/wayland/waylandxdgdialogv1_p.h b/src/platforms/wayland/waylandxdgdialogv1_p.h
new file mode 100644
index 00000000..9ec7c2bf
--- /dev/null
+++ b/src/platforms/wayland/waylandxdgdialogv1_p.h
@@ -0,0 +1,36 @@
+/*
+    SPDX-FileCopyrightText: 2025 Kai Uwe Broulik <kde@broulik.de>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+#ifndef WAYLANDXDGDIALOGV1_P_H
+#define WAYLANDXDGDIALOGV1_P_H
+
+#include "qwayland-xdg-dialog-v1.h"
+
+#include <QObject>
+#include <QtWaylandClient/QWaylandClientExtension>
+
+class WaylandXdgDialogV1 : public QObject, public QtWayland::xdg_dialog_v1
+{
+    Q_OBJECT
+public:
+    explicit WaylandXdgDialogV1(::xdg_dialog_v1 *object);
+    ~WaylandXdgDialogV1() override;
+};
+
+class WaylandXdgDialogWmV1 : public QWaylandClientExtensionTemplate<WaylandXdgDialogWmV1>, public QtWayland::xdg_wm_dialog_v1
+{
+public:
+    ~WaylandXdgDialogWmV1() override;
+
+    static WaylandXdgDialogWmV1 &self();
+
+    WaylandXdgDialogV1 *getDialog(struct ::xdg_toplevel *toplevel);
+
+private:
+    WaylandXdgDialogWmV1();
+};
+
+#endif // WAYLANDXDGDIALOGV1_P_H
diff --git a/src/platforms/wayland/windowsystem.cpp b/src/platforms/wayland/windowsystem.cpp
index e027bf96..bc44af0b 100644
--- a/src/platforms/wayland/windowsystem.cpp
+++ b/src/platforms/wayland/windowsystem.cpp
@@ -8,6 +8,7 @@
 #include "logging.h"
 #include "surfacehelper.h"
 #include "waylandxdgactivationv1_p.h"
+#include "waylandxdgdialogv1_p.h"
 #include "waylandxdgforeignv2_p.h"
 
 #include <KWaylandExtras>
@@ -16,10 +17,12 @@
 #include "qwayland-plasma-window-management.h"
 #include <QEvent>
 #include <QGuiApplication>
+#include <QLibraryInfo>
 #include <QPixmap>
 #include <QPoint>
 #include <QString>
 #include <QTimer>
+#include <QVersionNumber>
 #include <QWaylandClientExtensionTemplate>
 #include <QWindow>
 #include <qpa/qplatformnativeinterface.h>
@@ -284,6 +287,18 @@ void WindowSystem::doSetMainWindow(QWindow *window, const QString &handle)
     connect(imported, &QObject::destroyed, waylandWindow, [waylandWindow] {
         waylandWindow->setProperty(c_kdeXdgForeignImportedProperty, QVariant());
     });
+
+    // Before Qt 6.10, Qt sets XDG Dialog modal only when it has a transient parent.
+    if (window->modality() != Qt::NonModal && QLibraryInfo::version() < QVersionNumber(6, 10, 0)) {
+        auto &xdgDialog = WaylandXdgDialogWmV1::self();
+        if (xdgDialog.isActive()) {
+            if (auto *xdgToplevel = xdgToplevelForWindow(window)) {
+                auto *dialog = xdgDialog.getDialog(xdgToplevel);
+                dialog->set_modal();
+                dialog->setParent(waylandWindow);
+            }
+        }
+    }
 }
 
 #include "moc_windowsystem.cpp"
-- 
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