QML: save file on Android

I have been trying to make a test Android application which asks a user to specify the file name and writes some data there. Starting from the default QtQuick Controls 2 application (Qt 5.7.0), I changed it to provide FileDialog:

Code:

---

import QtQuick 2.7
import QtQuick.Dialogs 1.2
 
Page1Form
{
    MessageDialog {
         id: messageDialog
         onAccepted: {
             Qt.quit()
         }
     }
 
    FileDialog
    {
        id: saveFileDialog
        title: "Please save a file"
        folder: "/sdcard"
        selectExisting: false
 
        onAccepted:
        {
            messageDialog.text = fileWriter.testWrite(saveFileDialog.fileUrl)
            messageDialog.visible = true
        }
    }   // FileDialog
 
    button1.onClicked: {
        saveFileDialog.visible = true
 
    }
    button2.onClicked: {
        console.log("Button 2 clicked.");
    }
}

---

In the main.cpp I have this:

Code:

---

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include <QQuickStyle>
#include <QtCore>
 
#include "filewriter.h"
 
 
 
int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);
    QQuickStyle::setStyle("Material");
 
 
    qmlRegisterUncreatableType<FileWriter>("FileWriter", 1, 0, "FileWriter", "FileWriter is uncreatable.");
 
    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("fileWriter", new FileWriter);
    engine.load(QUrl(QLatin1String("qrc:/main.qml")));
 
    qDebug() << QProcess::systemEnvironment();
 
    return app.exec();
}

---

A couple of issues emerged:

First, with AA_EnableHighDpiScaling the file dialog is incorrectly displayed on my Sony Xperia Z3:
Attachment 12328

However, the main window seems to look nice:
Attachment 12329

Without dpi scaling it looks better, but it is still hardly usable:
Attachment 12330
It's inconvenient to browse and I don't even see how to type a file name. Is there a more user-friendly way to select files/folders in QML? Any examples? It seems to be a common task.

Despite having added android.permission.WRITE_EXTERNAL_STORAGE to AndroidManifest.xml when I launch the application it has this permission disabled by default. So I have to go to settings on my phone and turn them on manually. Otherwise it doesn't see the SD card content. How can I activate this permission automatically?

Finally, even if I enable WRITE_EXTERNAL_STORAGE permission, FileDialog doesn't seem to honor folder: "/sdcard", showing some default location. But according to the system environment the path exists:

Quote:

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PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin", "ANDROID_BOOTLOGO=1", "ANDROID_ROOT=/system", "ANDROID_ASSETS=/system/app", "ANDROID_DATA=/data", "ANDROID_STORAGE=/storage", "EXTERNAL_STORAGE=/sdcard", "ASEC_MOUNTPOINT=/mnt/asec", "BOOTCLASSPATH=/system/framework/core-libart.jar:/system/framework/conscrypt.jar:/system/framework/okhttp.jar:/system/framework/core-junit.jar:/system/framework/bouncycastle.jar:/system/framework/ext.jar:/system/framework/framework.jar:/system/framework/telephony-common.jar:/system/framework/voip-common.jar:/system/framework/ims-common.jar:/system/framework/apache-xml.jar:/system/framework/org.apache.http.legacy.boot.jar:/system/framework/tcmiface.jar:/system/framework/qcmediaplayer.jar:/system/framework/WfdCommon.jar:/system/framework/oem-services.jar:/system/framework/com.qti.dpmframework.jar:/system/framework/dpmapi.jar:/system/framework/com.qti.location.sdk.jar", "SYSTEMSERVERCLASSPATH=/system/framework/servi

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Any help is appreciated