如何实现2个应用程序之间的拖放？

Question

I'm trying to create an application, which will communicate through QLocalServer / QLocalSocket . The server name passing mechanism I planned to implement using the drag&drop mechanism. The mechanism is like the following:

• create QLocalServer in one application and QLocalSocket in the other,
• the server starts listening to some address,
• when you drag&drop some specified widget from the first app to the other, it must pass the address via QMimeData ,
• the second app gets the server address and connects to it.

I have implemented some code, but it seems, that drag&drop between applications make some changes in mimeData object. Here are code snippets and the result I have got:

mouseMoveEvent(QMouseEvent* event)
{
    if (!__drag_options.__drag_started)
        return;

    if (distance(__drag_options.__drag_started_position, event->pos()) < DRAG_DISTANCE)
        return;

    QDrag drag(this);
    QMimeData* mimeData = new QMimeData;
    mimeData->setData("type", "pin");
    mimeData->setData("address", __address);
    drag.setMimeData(mimeData);
    drag.exec(Qt::MoveAction);
}

dropEvent(QDropEvent* event)
{
    qDebug() << "dropEvent " << event->mimeData()->formats();
    const QMimeData* mime = event->mimeData();
    QString serverName = mime->data("pin_name");
    __socket->connectToServer(serverName);
}

and the result is

dragEnterEvent ("application/x-qt-windows-mime;value=\\"type\\"", "application/x-qt-windows-mime;value=\\"address\\"")

As you can see there's no mime named "address".

Any suggestions on how to get to the target?

Answer 1

I suggest you use a standard mime type like json or application/json (and send your data encoded in JSON), or XML, or ...

If you use a custom mime type, you have to live with the fact that Qt changes that mime type so it is more standard conformant.

As long as you stay within one application, your mime types won't be touched.

As soon as you drag from one application to another, you need the clipboard or such of the platform. (If I recall correctly, Windows only supports some of the possible mime types.)