Windows: Fix modal dialogs for declarative.

Make it possible to show a modal dialog by just calling show().
Start an idle timer, which will start the dialog thread.
This timer is stopped in exec().

Change-Id: I8f7352bf577b09a19be7df4484e0077bb1aa46ab
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

2 files changed, 38 insertions, 4 deletions

diff --git a/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp b/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp
index b4699b6306..e9c0cccc14 100644
--- a/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp
+++ b/src/plugins/platforms/windows/qwindowsdialoghelpers.cpp
@@ -450,7 +450,8 @@ protected:
 template <class BaseClass>
 QWindowsDialogHelperBase<BaseClass>::QWindowsDialogHelperBase() :
     m_nativeDialog(0),
-    m_ownerWindow(0)
+    m_ownerWindow(0),
+    m_timerId(0)
 {
 }
 
@@ -472,6 +473,12 @@ void QWindowsDialogHelperBase<BaseClass>::deleteNativeDialog()
 }
 
 template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::timerEvent(QTimerEvent *)
+{
+    startDialogThread();
+}
+
+template <class BaseClass>
 QWindowsNativeDialogBase *QWindowsDialogHelperBase<BaseClass>::ensureNativeDialog()
 {
     // Create dialog and apply common settings.
@@ -527,14 +534,36 @@ bool QWindowsDialogHelperBase<BaseClass>::show(Qt::WindowFlags,
         return false; // Was it changed in-between?
     if (!ensureNativeDialog())
         return false;
-    if (!modal) { // Modal dialogs are shown in separate slot.
-        QWindowsDialogThread *thread = new QWindowsDialogThread(this);
-        thread->start();
+    // Start a background thread to show the dialog. For modal dialogs,
+    // a subsequent call to exec() may follow. So, start an idle timer
+    // which will start the dialog thread. If exec() is then called, the
+    // timer is stopped and dialog->exec() is called directly.
+    if (modal) {
+        m_timerId = this->startTimer(0);
+    } else {
+        startDialogThread();
     }
     return true;
 }
 
 template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::startDialogThread()
+{
+    QWindowsDialogThread *thread = new QWindowsDialogThread(this);
+    thread->start();
+    stopTimer();
+}
+
+template <class BaseClass>
+void QWindowsDialogHelperBase<BaseClass>::stopTimer()
+{
+    if (m_timerId) {
+        this->killTimer(m_timerId);
+        m_timerId = 0;
+    }
+}
+
+template <class BaseClass>
 void QWindowsDialogHelperBase<BaseClass>::hide()
 {
     if (m_nativeDialog)
@@ -547,6 +576,7 @@ void QWindowsDialogHelperBase<BaseClass>::exec()
 {
     if (QWindowsContext::verboseDialogs)
         qDebug("%s" , __FUNCTION__);
+    stopTimer();
     if (QWindowsNativeDialogBase *nd = nativeDialog()) {
          nd->exec(m_ownerWindow);
          deleteNativeDialog();
diff --git a/src/plugins/platforms/windows/qwindowsdialoghelpers.h b/src/plugins/platforms/windows/qwindowsdialoghelpers.h
index a46caf0e1e..7884f398f3 100644
--- a/src/plugins/platforms/windows/qwindowsdialoghelpers.h
+++ b/src/plugins/platforms/windows/qwindowsdialoghelpers.h
@@ -81,13 +81,17 @@ protected:
     QWindowsNativeDialogBase *nativeDialog() const;
     inline bool hasNativeDialog() const { return m_nativeDialog; }
     void deleteNativeDialog();
+    void timerEvent(QTimerEvent *);
 
 private:
     virtual QWindowsNativeDialogBase *createNativeDialog() = 0;
     inline QWindowsNativeDialogBase *ensureNativeDialog();
+    inline void startDialogThread();
+    inline void stopTimer();
 
     QWindowsNativeDialogBase *m_nativeDialog;
     HWND m_ownerWindow;
+    int m_timerId;
 };
 
 QT_END_NAMESPACE