拖放问题 [英] Issue with drag and drop

问题描述

我使用以下代码将文件拖放到c＃winforms应用程序中。我遇到的问题是DragDrop事件处理程序需要一段时间，在这段时间内，我无法使用从中拖动文件的窗口。

I use the following code to drag and drop a file into a c# winforms application. The issue I have is that the DragDrop event handler takes a while, and during this time I can't use the window from which I dragged the file. How can this be fixed?

private void FormMain_DragDrop(object sender, DragEventArgs e)
{
    string[] s = (string[])e.Data.GetData(DataFormats.FileDrop, false);
    // do some long operation
}

private void FormMain_DragEnter(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
    e.Effect = DragDropEffects.All;
else
    e.Effect = DragDropEffects.None;
}

推荐答案

您可以使用 BackgroundWorker 在不同的线程中执行所需的操作，如下所示：

You may use a BackgroundWorker to do the operation that you need in different thread like the following :

    BackgroundWorker bgw;

    public Form1()
    {
        InitializeComponent();
        bgw = new BackgroundWorker();
        bgw.DoWork += bgw_DoWork;
    }

    private void Form1_DragDrop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(DataFormats.FileDrop))
        {
            string[] s = (string[])e.Data.GetData(DataFormats.FileDrop, false);
            bgw.RunWorkerAsync(s);
        }

    }

对于您的问题跨线程操作，请尝试使用 调用 这样的方法：

Also for your issue "cross thread operation", try to use the Invoke Method like this :

    void bgw_DoWork(object sender, DoWorkEventArgs e)
    {
        Invoke(new Action<object>((args) =>
        {
            string[] files = (string[])args;

        }), e.Argument);
    }

最好使用 GetDataPresent 如上。

Its better to check if the dropped items are files using GetDataPresent like above.

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