我正在尝试通过拖放功能上传文件.我成功地完成了UI工作,但是我无法访问在后端丢弃的对象.如果我在代码后面做的话,我能够成功地抓住对象,但我正在尝试采用MVVM方法.
AttachmentView.xaml
Cal:Message.Attach="[Drop] = [SaveFile($eventArgs)]"
Attachmentviewmodel.cs
public virtual async void SaveFile(DragEventArgs e)
{
var fileStream = new FileStream([File name goes here],FileMode.Open,FileAccess.Read);
}
我试过EventArgs,我找不到文件对象属性.测试代码时,DragEventArgs为null.
AttachmentView.xaml.cs
private void ImagePanel_Drop(object sender,DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
// Note that you can have more than one file.
string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
// Assuming you have one file that you care about,pass it off to whatever
// handling code you have defined.
Upload(files);
}
}
解决方法
您可以使用EventTriggerBehavior.您将向系统发送“Drop Event”.可能你需要一个用于事件参数的转换器.以下是使用listview的示例.
<core:EventTriggerBehavior EventName="SelectionChanged">
<core:InvokeCommandAction InputConverter="{StaticResource SelectionChangedConverter}"
InputConverterParameter="{Binding ElementName=CapturasListView}"
Command="{Binding OpenCapturaCommand}" />
</core:EventTriggerBehavior>
> https://blog.xamarin.com/turn-events-into-commands-with-behaviors/
> https://msdn.microsoft.com/en-us/magazine/dn237302.aspx
