Revamp QtWidgets/DragAndDrop examples to C++11

Introduce nullptr and replace foreach with new C++11 range based for
loops. Minor fixups of signals, file dialog usage.

Apply the same changes to the ItemViews/puzzle example since it
shares parts of the code with DragAndDrop/puzzle. Make some
changes to both examples to that the diff of the two becomes
small for easier comparison.

Task-number: QTBUG-60635
Change-Id: I8af824229ebac24d6ec151eae92176d227695490
Reviewed-by: Venugopal Shivashankar <Venugopal.Shivashankar@qt.io>
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 15 insertions, 8 deletions

diff --git a/examples/widgets/draganddrop/puzzle/mainwindow.cpp b/examples/widgets/draganddrop/puzzle/mainwindow.cpp
index 806133583a..1914519c68 100644
--- a/examples/widgets/draganddrop/puzzle/mainwindow.cpp
+++ b/examples/widgets/draganddrop/puzzle/mainwindow.cpp
@@ -67,12 +67,19 @@ MainWindow::MainWindow(QWidget *parent)
 
 void MainWindow::openImage()
 {
-    const QString fileName =
-        QFileDialog::getOpenFileName(this, tr("Open Image"), QString(),
-                                     tr("Image Files (*.png *.jpg *.bmp)"));
-
-    if (!fileName.isEmpty())
-        loadImage(fileName);
+    const QString directory =
+        QStandardPaths::standardLocations(QStandardPaths::PicturesLocation).value(0, QDir::homePath());
+    QFileDialog dialog(this, tr("Open Image"), directory);
+    dialog.setAcceptMode(QFileDialog::AcceptOpen);
+    dialog.setFileMode(QFileDialog::ExistingFile);
+    QStringList mimeTypeFilters;
+    for (const QByteArray &mimeTypeName : QImageReader::supportedMimeTypes())
+        mimeTypeFilters.append(mimeTypeName);
+    mimeTypeFilters.sort();
+    dialog.setMimeTypeFilters(mimeTypeFilters);
+    dialog.selectMimeTypeFilter("image/jpeg");
+    if (dialog.exec() == QDialog::Accepted)
+        loadImage(dialog.selectedFiles().constFirst());
 }
 
 void MainWindow::loadImage(const QString &fileName)
@@ -101,8 +108,8 @@ void MainWindow::setCompleted()
 void MainWindow::setupPuzzle()
 {
     int size = qMin(puzzleImage.width(), puzzleImage.height());
-    puzzleImage = puzzleImage.copy((puzzleImage.width() - size)/2,
-        (puzzleImage.height() - size)/2, size, size).scaled(puzzleWidget->width(),
+    puzzleImage = puzzleImage.copy((puzzleImage.width() - size) / 2,
+        (puzzleImage.height() - size) / 2, size, size).scaled(puzzleWidget->width(),
             puzzleWidget->height(), Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
 
     piecesList->clear();