从另一个方法调用的文件

问题描述

在这里新手问题。我有这个文件选择器：

 公共异步无效PickImage（）
{
    FileOpenPicker ImagePicker =新FileOpenPicker（）;
    ...
    StorageFile文件=等待ImagePicker.PickSingleFileAsync（）; //
    ...
}
 

和我想用在另一种方法这个图像选择器设置文件。事情是这样的：

 专用异步无效CreateButton_Click（对象发件人，RoutedEventArgs E）
{
    ......一个从PickImage（）
                                    v
    StorageFile copyImage =等待file.CopyAsync（DateTimeFolder，形象，NameCollisionOption.ReplaceExisting）;
    ...
}
 

这显然不是这样工作。我该怎么办呢？

---

好吧，根据我得到的答案，这是我想出了：

 公共异步任务＆LT; StorageFile＆GT; PickImage（）
{
    FileOpenPicker ImagePicker =新FileOpenPicker（）;
    ImagePicker.FileTypeFilter.Add（JPG）;
    ImagePicker.FileTypeFilter.Add（JPEG）;
    ImagePicker.FileTypeFilter.Add（PNG）;
    ImagePicker.ViewMode = PickerViewMode.Thumbnail;
    ImagePicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
    StorageFile文件=等待ImagePicker.PickSingleFileAsync（）;
    如果（文件！= NULL）
    {
        IRandomAccessStream的ImageStream =等待file.OpenAsync（FileAccessMode.Read）;
        VAR bmpImage =新Windows.UI.Xaml.Media.Imaging.BitmapImage（）;
        bmpImage.De codePixelHeight = 150;
        bmpImage.De codePixelWidth = 310;
        bmpImage.SetSource（的ImageStream）;
        图片preview.Source = bmpImage;
    }
    返回文件;
}////私人异步无效CreateButton_Click（对象发件人，RoutedEventArgs E）
{
    ...
    串DateTimeNow = DateTime.Now.ToString（HHmmssddMMyyyy）;
    StorageFolder文档= KnownFolders.DocumentsLibrary;
    StorageFolder MYDIR =等待docs.CreateFolderAsync（我的目录，Windows.Storage.CreationCollisionOption.OpenIfExists）;
    StorageFolder DateTimeFolder =等待myDir.CreateFolderAsync（DateTimeNow）;
    // StorageFile图像=等待PickImage（）;
    StorageFile copyImage =等待PickImage（）CopyAsync（DateTimeFolder，形象，NameCollisionOption.ReplaceExisting）。
    ...
}
 

但最后一行给我一个错误：

解决方案

You need to either set a field in the class or return the StorageFile. I would suggest changing PickImage() to return the StorageFile so you're code would instead look like this;

public async StorageFile PickImage()
{
    FileOpenPicker ImagePicker = new FileOpenPicker();
    ...
    return await ImagePicker.PickSingleFileAsync(); //
    ...
}


private async void CreateButton_Click(object sender, RoutedEventArgs e)
{
    StorageFile pickedFile = await PickImage();
    StorageFile copyImage = await file.CopyAsync(DateTimeFolder, "image", NameCollisionOption.ReplaceExisting);
    ...
}

Or something to that effect. I'm slightly confused by the second line in your CreateButton_Click method because I thought you wanted to operate on the file from PickImage but instead you're creating a new file. If you want the StorageFile to persist just make it a field on the form class and set it in PickImage

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