Add QX11Info::isCompositingManagerRunning() function

Task-number: QTBUG-41195
Change-Id: Id4b385478dad85dd02c484fe9c44666bae46268b
Reviewed-by: Błażej Szczygieł <spaz16@wp.pl>
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

3 files changed, 29 insertions, 0 deletions

diff --git a/src/x11extras/qx11info_x11.cpp b/src/x11extras/qx11info_x11.cpp
index e5aa678..a201547 100644
--- a/src/x11extras/qx11info_x11.cpp
+++ b/src/x11extras/qx11info_x11.cpp
@@ -376,4 +376,29 @@ xcb_connection_t *QX11Info::connection()
     return reinterpret_cast<xcb_connection_t *>(connection);
 }
 
+/*!
+    \since 5.7
+
+    Returns true if there is a compositing manager running for the connection
+    attached to \a screen.
+
+    If \l -1, the application primary screen is used.
+*/
+bool QX11Info::isCompositingManagerRunning(int screen)
+{
+    if (!qApp)
+        return false;
+    QPlatformNativeInterface *native = qApp->platformNativeInterface();
+    if (!native)
+        return false;
+
+    QScreen *scr = screen == -1 ?  QGuiApplication::primaryScreen() : findScreenForVirtualDesktop(screen);
+    if (!scr) {
+        qWarning() << "isCompositingManagerRunning: Could not find screen number" << screen;
+        return false;
+    }
+
+    return native->nativeResourceForScreen(QByteArray("compositingEnabled"), scr);
+}
+
 QT_END_NAMESPACE
diff --git a/src/x11extras/qx11info_x11.h b/src/x11extras/qx11info_x11.h
index 620428d..ab72686 100644
--- a/src/x11extras/qx11info_x11.h
+++ b/src/x11extras/qx11info_x11.h
@@ -73,6 +73,8 @@ public:
     static Display *display();
     static xcb_connection_t *connection();
 
+    static bool isCompositingManagerRunning(int screen = -1);
+
 private:
     QX11Info();
 };
diff --git a/tests/auto/qx11info/tst_qx11info.cpp b/tests/auto/qx11info/tst_qx11info.cpp
index 0a19d7f..a27f443 100644
--- a/tests/auto/qx11info/tst_qx11info.cpp
+++ b/tests/auto/qx11info/tst_qx11info.cpp
@@ -96,6 +96,8 @@ void tst_QX11Info::staticFunctionsBeforeQApplication()
     appUserTime = QX11Info::appUserTime();
     QCOMPARE(appTime, 0ul);
     QCOMPARE(appTime, 0ul);
+
+    QX11Info::isCompositingManagerRunning();
 }
 
 static const char idFromEnv[] = "startupid_TIME123456";