Enhance quickwidget example with all grabbing cases

Add a demo of QQuickItem::grabToImage(), in addition to grabFramebuffer()
and render(). This way all possible approaches are demonstrated and tested.

Task-number: QTBUG-55879
Change-Id: I13c427730c416f0d87f83092627e2cb46aba2cc4
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

2 files changed, 28 insertions, 8 deletions

diff --git a/examples/quick/quickwidgets/quickwidget/main.cpp b/examples/quick/quickwidgets/quickwidget/main.cpp
index 65258d958e..3f3638a43f 100644
--- a/examples/quick/quickwidgets/quickwidget/main.cpp
+++ b/examples/quick/quickwidgets/quickwidget/main.cpp
@@ -39,6 +39,7 @@
 ****************************************************************************/
 
 #include <QQuickWidget>
+#include <QQuickItem>
 #include <QQmlError>
 #include <QtWidgets>
 
@@ -50,8 +51,9 @@ public:
 private slots:
     void quickWidgetStatusChanged(QQuickWidget::Status);
     void sceneGraphError(QQuickWindow::SceneGraphError error, const QString &message);
-    void grabToFile();
-    void renderToFile();
+    void grabFramebuffer();
+    void renderToPixmap();
+    void grabToImage();
 
 private:
     QQuickWidget *m_quickWidget;
@@ -91,8 +93,9 @@ MainWindow::MainWindow()
     setCentralWidget(centralWidget);
 
     QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
-    fileMenu->addAction(tr("Grab to imFage"), this, &MainWindow::grabToFile);
-    fileMenu->addAction(tr("Render to pixmap"), this, &MainWindow::renderToFile);
+    fileMenu->addAction(tr("Grab framebuffer"), this, &MainWindow::grabFramebuffer);
+    fileMenu->addAction(tr("Render to pixmap"), this, &MainWindow::renderToPixmap);
+    fileMenu->addAction(tr("Grab via grabToImage"), this, &MainWindow::grabToImage);
     fileMenu->addAction(tr("Quit"), qApp, &QCoreApplication::quit);
 }
 
@@ -113,8 +116,7 @@ void MainWindow::sceneGraphError(QQuickWindow::SceneGraphError, const QString &m
 
 template<class T> void saveToFile(QWidget *parent, T *saveable)
 {
-    QString t;
-    QFileDialog fd(parent, t, QString());
+    QFileDialog fd(parent);
     fd.setAcceptMode(QFileDialog::AcceptSave);
     fd.setDefaultSuffix("png");
     fd.selectFile("test.png");
@@ -122,19 +124,31 @@ template<class T> void saveToFile(QWidget *parent, T *saveable)
         saveable->save(fd.selectedFiles().first());
 }
 
-void MainWindow::grabToFile()
+void MainWindow::grabFramebuffer()
 {
     QImage image = m_quickWidget->grabFramebuffer();
     saveToFile(this, &image);
 }
 
-void MainWindow::renderToFile()
+void MainWindow::renderToPixmap()
 {
     QPixmap pixmap(m_quickWidget->size());
     m_quickWidget->render(&pixmap);
     saveToFile(this, &pixmap);
 }
 
+void MainWindow::grabToImage()
+{
+    QFileDialog fd(this);
+    fd.setAcceptMode(QFileDialog::AcceptSave);
+    fd.setDefaultSuffix("png");
+    fd.selectFile("test_grabToImage.png");
+    if (fd.exec() == QDialog::Accepted) {
+        QMetaObject::invokeMethod(m_quickWidget->rootObject(), "performLayerBasedGrab",
+                                  Q_ARG(QVariant, fd.selectedFiles().first()));
+    }
+}
+
 int main(int argc, char **argv)
 {
     QApplication app(argc, argv);
diff --git a/examples/quick/quickwidgets/quickwidget/rotatingsquare.qml b/examples/quick/quickwidgets/quickwidget/rotatingsquare.qml
index 0c25eddf88..03b1114d20 100644
--- a/examples/quick/quickwidgets/quickwidget/rotatingsquare.qml
+++ b/examples/quick/quickwidgets/quickwidget/rotatingsquare.qml
@@ -57,4 +57,10 @@ Rectangle {
         anchors.centerIn: parent
         text: "Qt Quick running in a widget"
     }
+
+    function performLayerBasedGrab(fn) {
+        root.grabToImage(function(result) {
+            result.saveToFile(fn);
+        });
+    }
 }