Drag and drop image file from explorer to application

Question

I'm trying to drag an image file from explorer into my wpf image control. My current code is

private void Image_Drop(object sender, DragEventArgs e)
{
    string fpath = (string)e.Data.GetData(DataFormats.StringFormat); 
    BitmapImage tmpImage = new BitmapImage((new Uri(fpath))); 
    testImg.Source = tmpImage;
}

Which is currently giving me NullReferenceException error when I drop the file on the control.

Update:

Using Patrick's suggestion, by changing the code to this

private void Image_Drop(object sender, DragEventArgs e)
{
    object data = e.Data.GetData(DataFormats.FileDrop);

    foreach (string str in (string[])data)
    {
        BitmapImage tmpImage = new BitmapImage((new Uri(str)));
        testImg.Source = tmpImage;
    }
}

The image correctly update the source. Will probably need to add code for handling multiple images selection drop.

Answer 1

You should use the DataFormats.FileDrop. It will give a list of file names in the GetData. This is a working example from my own app:

object data = e.Data.GetData(DataFormats.FileDrop);

if (data is string[])
{
    string[] files = (string[])data;
}

Answer 2

You are trying to get a file as a string, so I imagine it's your e.Data.GetData(DataFormats.StringFormat) line that is throwing. If you're dropping a bitmap onto your control then you can treat it as such. Try this.

private void Image_Drop(object sender, DragEventArgs e)
{
    BitmapImage tmpImage = e.Data.GetData(DataFormats.Bitmap);
    testImg.Source = tmpImage;
}

Although I recommend you put in code to ensure you are checking the type of what has been dragged onto your control before assuming it is a bitmap.