Add File System Explorer example

This example shows the customization of Qt Quick Controls by
implementing a simple file system explorer. Using a C++ model, entries
are visualized in a TreeView, and text files can be read.

Fixes: QTBUG-108289
Change-Id: I966dcf65e40d3b727889dc14c65edd0ffcc1b878
Reviewed-by: Mitch Curtis <[email protected]>

1 files changed, 48 insertions, 0 deletions

diff --git a/examples/quickcontrols/filesystemexplorer/filesystemmodel.cpp b/examples/quickcontrols/filesystemexplorer/filesystemmodel.cpp
new file mode 100644
index 0000000000..45b47737f5
--- /dev/null
+++ b/examples/quickcontrols/filesystemexplorer/filesystemmodel.cpp
@@ -0,0 +1,48 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "filesystemmodel.h"
+
+#include <QMimeDatabase>
+#include <QStandardPaths>
+
+FileSystemModel::FileSystemModel(QObject *parent) : QFileSystemModel(parent)
+{
+    setRootPath(QStandardPaths::writableLocation(QStandardPaths::HomeLocation));
+}
+
+int FileSystemModel::columnCount(const QModelIndex &parent) const
+{
+    Q_UNUSED(parent);
+    return 1;
+}
+
+QString FileSystemModel::readFile(const QString &filePath)
+{
+    // Don't issue errors for an empty path, as the initial binding
+    // will result in an empty path, and that's OK.
+    if (filePath.isEmpty())
+        return {};
+
+    QFile file(filePath);
+
+    const QMimeDatabase db;
+    const QMimeType mime = db.mimeTypeForFile(QFileInfo(file));
+
+    if (file.size() >= 2'000'000)
+        return tr("File size is too big.\nYou can read files up to %1 MB.").arg(2);
+
+    // Check if the mimetype is supported and return the content.
+    const auto mimeTypesForFile = mime.parentMimeTypes();
+    for (const auto &m : mimeTypesForFile) {
+        if (m.contains("text", Qt::CaseInsensitive)
+                || mime.comment().contains("text", Qt::CaseInsensitive)) {
+            if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
+                return tr("Error opening the File!");
+
+            QTextStream stream(&file);
+            return stream.readAll();
+        }
+    }
+    return tr("Filetype not supported!");
+}