Add an application attribute to control XInitThreads().

In order to make Xlib thread-safe XInitThreads() needs to be the first
Xlib call issued. This attribute controls this behavior. Having Xlib
thread-safe will most likely incur some overhead, which is why this
is not done by default.

4 files changed, 9 insertions, 2 deletions

diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index a9c56f6..84ab567 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -530,6 +530,7 @@ public:
         AA_DontUseNativeMenuBar = 6,
         AA_MacDontSwapCtrlAndMeta = 7,
         AA_S60DontConstructApplicationPanes = 8,
+        AA_X11InitThreads = 9,
 
         // Add new attributes before this line
         AA_AttributeCount
diff --git a/src/corelib/global/qnamespace.qdoc b/src/corelib/global/qnamespace.qdoc
index 7eae3a5..ce1176d 100644
--- a/src/corelib/global/qnamespace.qdoc
+++ b/src/corelib/global/qnamespace.qdoc
@@ -170,6 +170,10 @@
            whole lifetime. This attribute must be set before QApplication is
            constructed.
 
+    \value AA_X11InitThreads Calls XInitThreads() as part of the QApplication
+           construction in order to make Xlib calls thread-safe.
+
+
     \omitvalue AA_AttributeCount
 */
 
diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp
index e630e80..a2b0b95 100644
--- a/src/gui/image/qpixmap.cpp
+++ b/src/gui/image/qpixmap.cpp
@@ -94,13 +94,12 @@ Q_GUI_EXPORT qint64 qt_pixmap_id(const QPixmap &pixmap)
 
 static bool qt_pixmap_thread_test()
 {
-    return true;
     if (!qApp) {
         qFatal("QPixmap: Must construct a QApplication before a QPaintDevice");
         return false;
     }
 #ifndef Q_WS_WIN
-    if (qApp->thread() != QThread::currentThread()) {
+    if (!QApplication::testAttribute(Qt::AA_X11InitThreads) && qApp->thread() != QThread::currentThread()) {
         qWarning("QPixmap: It is not safe to use pixmaps outside the GUI thread");
         return false;
     }
diff --git a/src/gui/kernel/qapplication_x11.cpp b/src/gui/kernel/qapplication_x11.cpp
index 9d5a7c0..5e212ca 100644
--- a/src/gui/kernel/qapplication_x11.cpp
+++ b/src/gui/kernel/qapplication_x11.cpp
@@ -1710,6 +1710,9 @@ void qt_init(QApplicationPrivate *priv, int,
     } else {
         // Qt controls everything (default)
 
+        if (QApplication::testAttribute(Qt::AA_X11InitThreads))
+            XInitThreads();
+
         // Set application name and class
         char *app_class = 0;
         if (argv && argv[0]) {