Use queued connection to thread-safe MainWindow error handling

Up to now, errors produced by threads were not directly shown in
the MainWindow. Code running in the GUI thread had to manually
show the errors.

This can be simplified by using Qt's queued connection as message
passing facility.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

5 files changed, 11 insertions, 20 deletions

diff --git a/desktop-widgets/downloadfromdivecomputer.cpp b/desktop-widgets/downloadfromdivecomputer.cpp
index fce287665..ac4fc320f 100644
--- a/desktop-widgets/downloadfromdivecomputer.cpp
+++ b/desktop-widgets/downloadfromdivecomputer.cpp
@@ -222,9 +222,6 @@ void DownloadFromDCWidget::updateState(states state)
 	else if (state == ERROR) {
 		timer->stop();
 
-		// Show messages that worker thread produced.
-		MainWindow::instance()->showErrors();
-
 		QMessageBox::critical(this, TITLE_OR_TEXT(tr("Error"), thread.error), QMessageBox::Ok);
 		markChildrenAsEnabled();
 		progress_bar_text = "";
diff --git a/desktop-widgets/mainwindow.cpp b/desktop-widgets/mainwindow.cpp
index 26c67a261..7fa12c524 100644
--- a/desktop-widgets/mainwindow.cpp
+++ b/desktop-widgets/mainwindow.cpp
@@ -91,21 +91,9 @@ MainWindow *MainWindow::m_Instance = NULL;
 
 extern "C" void showErrorFromC()
 {
-	// Show errors only if we are running in the GUI thread.
-	// If we're not in the GUI thread, let errors accumulate.
-	if (QThread::currentThread() != QCoreApplication::instance()->thread())
-		return;
-
 	MainWindow *mainwindow = MainWindow::instance();
 	if (mainwindow)
-		mainwindow->showErrors();
-}
-
-void MainWindow::showErrors()
-{
-	const char *error = get_error_string();
-	if (!empty_string(error))
-		getNotificationWidget()->showNotification(error, KMessageWidget::Error);
+		emit mainwindow->showError(get_error_string());
 }
 
 MainWindow::MainWindow() : QMainWindow(),
@@ -219,6 +207,7 @@ MainWindow::MainWindow() : QMainWindow(),
 	connect(plannerDetails->printPlan(), SIGNAL(pressed()), divePlannerWidget(), SLOT(printDecoPlan()));
 	connect(this, SIGNAL(startDiveSiteEdit()), this, SLOT(on_actionDiveSiteEdit_triggered()));
 	connect(information(), SIGNAL(diveSiteChanged(struct dive_site *)), mapWidget, SLOT(centerOnDiveSite(struct dive_site *)));
+	connect(this, &MainWindow::showError, ui.mainErrorMessage, &NotificationWidget::showError, Qt::AutoConnection);
 
 	wtu = new WindowTitleUpdate();
 	connect(WindowTitleUpdate::instance(), SIGNAL(updateTitle()), this, SLOT(setAutomaticTitle()));
diff --git a/desktop-widgets/mainwindow.h b/desktop-widgets/mainwindow.h
index 18b03cb61..09b1fd9da 100644
--- a/desktop-widgets/mainwindow.h
+++ b/desktop-widgets/mainwindow.h
@@ -88,10 +88,6 @@ public:
 	void enableDisableCloudActions();
 	void setCheckedActionFilterTags(bool checked);
 
-	// Shows errors that have accumulated.
-	// Must be called from GUI thread.
-	void showErrors();
-
 private
 slots:
 	/* file menu action */
@@ -159,6 +155,7 @@ protected:
 
 signals:
 	void startDiveSiteEdit();
+	void showError(QString message);
 
 public
 slots:
diff --git a/desktop-widgets/notificationwidget.cpp b/desktop-widgets/notificationwidget.cpp
index e0227010c..7c156ee5c 100644
--- a/desktop-widgets/notificationwidget.cpp
+++ b/desktop-widgets/notificationwidget.cpp
@@ -16,6 +16,11 @@ void NotificationWidget::showNotification(QString message, KMessageWidget::Messa
 	animatedShow();
 }
 
+void NotificationWidget::showError(QString message)
+{
+	showNotification(message, KMessageWidget::Error);
+}
+
 void NotificationWidget::hideNotification()
 {
 	animatedHide();
diff --git a/desktop-widgets/notificationwidget.h b/desktop-widgets/notificationwidget.h
index 70d94b8d6..93fc62605 100644
--- a/desktop-widgets/notificationwidget.h
+++ b/desktop-widgets/notificationwidget.h
@@ -21,6 +21,9 @@ public:
 	void hideNotification();
 	QString getNotificationText();
 
+public
+slots:
+	void showError(QString message);
 private:
 	QFutureWatcher<void> future_watcher;