How to test if a file exist on Android when the url comes from QML FileDialog?

[mbruel]

Hi,
I know that normally Qt.labs.platform.FileDialog doesn't support Android but it is kind of working by opening the default file browser.
I'm opening an image:

    FileDialog {
        id: imgDialog
        title: "Select an image file"
        folder: StandardPaths.standardLocations(StandardPaths.PicturesLocation)[0]
        nameFilters: "Image files (*.png *.jpeg *.jpg)"
        onAccepted: {
            print("new picture: "+file);
            dogPictureFile = file;
        }
    } // imgDialog

On my Android phone, a Xiaomi, I'm getting this url: content://com.android.providers.media.documents/document/image%3A455944

I'm saving this url in a Database and when I restart the app to load it, I'm using this C++ method:

QString Dog::pictureUrl() const
{
    if (_pictureUrl.isEmpty())
        return "images/dogIcon.png";

    QUrl url(_pictureUrl);
    QString path = url.path();
    qDebug() << "path of picture '"<< _pictureUrl << "' : " << path;

#if defined(Q_OS_ANDROID)
    return url.toString();
#else
    return QFile::exists(path) ? url.toString() : "images/dogIcon.png";
#endif
}

As you can see I don't know how to test if the image using the QML url exists...
If I don't have the #if defined(Q_OS_ANDROID), the QFile::exists(path) returns false and I'm getting the default picture :'(
Here is the debug output with the Path: path of picture ' "content://com.android.providers.media.documents/document/image%3A455944" ' : "/document/image:455944"

What can I do? any idea?

[mbruel]

PS: if I delete the image, I'm getting this warning message:
W MyApp: qrc:/MyApp.qml:48:5: QML Image: Cannot open: content://com.android.providers.media.documents/document/image%3A455944
it would be great if I could catch a signal or something but I suppose there not this kind of thing in QML... is it?

[mbruel]

Nobody?
I've find a solution (using this thread) but it involves to copy the image loaded in QML via a C++ method into QStandardPaths::writableLocation(QStandardPaths::AppDataLocation)
I obtain a "proper" path for my copied image that can be converted to url for QML using QUrl::fromLocalFile

I'd prefer not to do the copy, so if anyone have another solution, I'm still interested ;)

[fcarney]

You could try loading the entire URL into a hidden Image. Check the status using the onStatus method and check for null or error conditions. Then make decision about what URL is used to be displayed.

https://doc.qt.io/qt-5/qml-qtquick-image.html#status-prop

Edit: Does that URL resolve when used with Image?

[mbruel]

@fcarney
perfect that's exactly what I needed! my bad, I didn't go to the bottom of the documentation...
Yes QML Image loads perfectly this kind of url: content://com.android.providers.media.documents/document/image%3A455947
So I'm just storing it as a string and do the test in QML rather than in C++. No need of an hidden image, it can be done directly on the visible one with something like this:

    Image {
        id: dogPicture
        fillMode: Image.PreserveAspectFit;
        height: parent.height/2 - 8* spacing
        source: dog.pictureUrl
        anchors {
            top: parent.top
            topMargin : spacing
            horizontalCenter: parent.horizontalCenter
        }
        onStatusChanged: if (status === Image.Error) source = dog.dogIconDefault();
    }

with my C++ accessor being:

QString Dog::pictureUrl() const
{
    if (_pictureUrl.isEmpty())
        return sDogIconDefault;
    return QUrl(_pictureUrl).toString();
}

Thanks @fcarney ;)