Add native interface for X11 application, exposing display and connection

The major use-case of the now private QX11Info from Qt X11 Extras was
getting hold of the Xlib display and XCB connection, for example in KDE:

  https://lxr.kde.org/search?%21v=kf5-qt5&_filestring=&_string=QX11Info

A new native interface for QGuiApplication has now been added that
exposes these two properties, e.g.:

  if (auto *x11App = app.nativeInterface<QX11Application>())
      qDebug() << x11App->display() << x11App->connection();

To avoid type clashes one of the enum values of QXcbNativeInterface's
ResourceType had to be renamed.

Pick-to: 6.2
Task-number: QTBUG-93633
Change-Id: I2e366a2bb88bd3965ac6172ad000ae32209f43e7
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

2 files changed, 15 insertions, 11 deletions

diff --git a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
index 95c552a468..55633aade7 100644
--- a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
+++ b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
@@ -118,7 +118,7 @@ void *QXcbNativeInterface::nativeResourceForIntegration(const QByteArray &resour
     case RootWindow:
         result = rootWindow();
         break;
-    case Display:
+    case XDisplay:
         result = display();
         break;
     case AtspiBus:
@@ -155,7 +155,7 @@ void *QXcbNativeInterface::nativeResourceForScreen(const QByteArray &resourceStr
 
     const QXcbScreen *xcbScreen = static_cast<QXcbScreen *>(screen->handle());
     switch (resourceType(lowerCaseResource)) {
-    case Display:
+    case XDisplay:
 #if QT_CONFIG(xcb_xlib)
         result = xcbScreen->connection()->xlib_display();
 #endif
@@ -203,7 +203,7 @@ void *QXcbNativeInterface::nativeResourceForWindow(const QByteArray &resourceStr
         return result;
 
     switch (resourceType(lowerCaseResource)) {
-    case Display:
+    case XDisplay:
         result = displayForWindow(window);
         break;
     case Connection:
@@ -365,18 +365,17 @@ void *QXcbNativeInterface::rootWindow()
     return nullptr;
 }
 
-void *QXcbNativeInterface::display()
+Display *QXcbNativeInterface::display() const
 {
 #if QT_CONFIG(xcb_xlib)
     QXcbIntegration *integration = QXcbIntegration::instance();
-    QXcbConnection *connection = integration->connection();
-    if (connection)
-        return connection->xlib_display();
+    if (QXcbConnection *connection = integration->connection())
+        return reinterpret_cast<Display *>(connection->xlib_display());
 #endif
     return nullptr;
 }
 
-void *QXcbNativeInterface::connection()
+xcb_connection_t *QXcbNativeInterface::connection() const
 {
     QXcbIntegration *integration = QXcbIntegration::instance();
     return integration->connection()->xcb_connection();
diff --git a/src/plugins/platforms/xcb/qxcbnativeinterface.h b/src/plugins/platforms/xcb/qxcbnativeinterface.h
index 4656f46be5..5508d57679 100644
--- a/src/plugins/platforms/xcb/qxcbnativeinterface.h
+++ b/src/plugins/platforms/xcb/qxcbnativeinterface.h
@@ -45,6 +45,8 @@
 
 #include <QtCore/QRect>
 
+#include <QtGui/qguiapplication.h>
+
 #include "qxcbexport.h"
 #include "qxcbconnection.h"
 
@@ -54,11 +56,12 @@ class QXcbScreen;
 class QXcbNativeInterfaceHandler;
 
 class Q_XCB_EXPORT QXcbNativeInterface : public QPlatformNativeInterface
+    , public QNativeInterface::QX11Application
 {
     Q_OBJECT
 public:
     enum ResourceType {
-        Display,
+        XDisplay,
         Connection,
         Screen,
         AppTime,
@@ -109,9 +112,11 @@ public:
     void *startupId();
     void *x11Screen();
     void *rootWindow();
-    void *display();
+
+    Display *display() const override;
+    xcb_connection_t *connection() const override;
+
     void *atspiBus();
-    void *connection();
     static void setStartupId(const char *);
     static void setAppTime(QScreen *screen, xcb_timestamp_t time);
     static void setAppUserTime(QScreen *screen, xcb_timestamp_t time);