Implement startup notification spec again.

This functionality was in Qt4's qapplication_x11.cpp and was missing
from the XCB QPA plugin. Ported the code from xlib to xcb.

This code was actually tested (with plasma), unlike the Qt-4.8 code which
skipped every other character...
    for (uint i = 0; i < 20 && i + sent <= length; i++)
        xevent.xclient.data.b[i] = message[i + sent++];

Provide a QPA native-function for accessing the startup id, for cases where
an application doesn't show a window, but starts another app instead, or asks
a running app to show the window on its behalf.

Change-Id: If392179efddd70a51c45a8fab4fb9d753913094a
Reviewed-by: David Faure (KDE) <faure@kde.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index 38b4c873ad..a6ead49a27 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -233,6 +233,40 @@ QWindow *QXcbScreen::topLevelAt(const QPoint &p) const
     return 0;
 }
 
+void QXcbScreen::windowShown(QXcbWindow *window)
+{
+    // Freedesktop.org Startup Notification
+    if (!connection()->startupId().isEmpty() && window->window()->isTopLevel()) {
+        sendStartupMessage(QByteArrayLiteral("remove: ID=") + connection()->startupId());
+        connection()->clearStartupId();
+    }
+}
+
+void QXcbScreen::sendStartupMessage(const QByteArray &message) const
+{
+    xcb_window_t rootWindow = root();
+
+    xcb_client_message_event_t ev;
+    ev.response_type = XCB_CLIENT_MESSAGE;
+    ev.format = 8;
+    ev.type = connection()->atom(QXcbAtom::_NET_STARTUP_INFO_BEGIN);
+    ev.window = rootWindow;
+    int sent = 0;
+    int length = message.length() + 1; // include NUL byte
+    const char *data = message.constData();
+    do {
+        if (sent == 20)
+            ev.type = connection()->atom(QXcbAtom::_NET_STARTUP_INFO);
+
+        const int start = sent;
+        const int numBytes = qMin(length - start, 20);
+        memcpy(ev.data.data8, data + start, numBytes);
+        xcb_send_event(connection()->xcb_connection(), false, rootWindow, XCB_EVENT_MASK_PROPERTY_CHANGE, (const char *) &ev);
+
+        sent += numBytes;
+    } while (sent < length);
+}
+
 const xcb_visualtype_t *QXcbScreen::visualForId(xcb_visualid_t visualid) const
 {
     QMap<xcb_visualid_t, xcb_visualtype_t>::const_iterator it = m_visuals.find(visualid);