qcam: Provide save image functionality

Implement a save image button on the toolbar which will take a current
viewfinder image and present the user with a QFileDialog to allow them
to choose where to save the image.

Utilise the QImageWriter to perform the output task.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/qcam/main_window.cpp

@@ -12,7 +12,10 @@
 
 #include <QComboBox>
 #include <QCoreApplication>
+#include <QFileDialog>
 #include <QIcon>
+#include <QImage>
+#include <QImageWriter>
 #include <QInputDialog>
 #include <QTimer>
 #include <QToolBar>
@@ -88,6 +91,9 @@ int MainWindow::createToolbars()
 	action = toolbar_->addAction(QIcon(":stop-circle.svg"), "stop");
 	connect(action, &QAction::triggered, this, &MainWindow::stopCapture);
 
+	action = toolbar_->addAction(QIcon(":save.svg"), "saveAs");
+	connect(action, &QAction::triggered, this, &MainWindow::saveImageAs);
+
 	return 0;
 }
 
@@ -339,6 +345,22 @@ void MainWindow::stopCapture()
 	setWindowTitle(title_);
 }
 
+void MainWindow::saveImageAs()
+{
+	QImage image = viewfinder_->getCurrentImage();
+
+	QString filename = QFileDialog::getSaveFileName(this, "Save Image", "",
+							"Image Files (*.png *.jpg *.jpeg)");
+
+	std::cout << "Save image to " << filename.toStdString() << std::endl;
+
+	if (filename.isEmpty())
+		return;
+
+	QImageWriter writer(filename);
+	writer.write(image);
+}
+
 void MainWindow::requestComplete(Request *request)
 {
 	if (request->status() == Request::RequestCancelled)