如何强制图像控件关闭在WPF中打开的文件 [英] How to force Image control to close the file that it opens in wpf

问题描述

我的wpf页面上有一个图像，该图像从硬盘上打开图像文件。用于定义图像的XAML是：

 < Image Canvas.Left = 65 Canvas.Top = 5 Width = 510高度= 255来源= {Binding Path = ImageFileName} /> 
  

我正在使用Caliburn Micro，并且ImageFileName已更新为图像控件应显示的文件名。 / p>

通过图像控件打开图像时，我需要更改文件。但是该文件已被图像控件锁定，我无法删除或复制该文件上的任何图像。打开文件后或需要在其上复制另一个文件时，如何强制Image关闭文件？

我检查了，没有CashOptio用于图像，所以我不能使用它。

解决方案

您可以使用如下所示的绑定转换器，它通过设置 BitmapCacheOption.OnLoad 。该文件将立即加载，之后不会被锁定。

 < Image Source = {Binding。 ..，
 Converter = {StaticResource local：StringToImageConverter}} /> 
  

转换器：

 公共类StringToImageConverter：IValueConverter 
 {
公共对象Convert（
对象值，类型targetType，对象参数，CultureInfo文化）
 {
对象结果= null; 
 var path =字符串形式的值； 
 
 if（！string.IsNullOrEmpty（path））
 {
 var image = new BitmapImage（）; 
 image.BeginInit（）; 
 image.CacheOption = BitmapCacheOption.OnLoad; 
 image.UriSource =新的Uri（路径）; 
 image.EndInit（）; 
结果=图片； 
} 
 
返回结果； 
} 
 
公共对象ConvertBack（对象值，类型targetType，对象参数，CultureInfo文化）
 {
 throw new NotSupportedException（）; 
} 
} 
  

更好的是，直接从FileStream加载BitmapImage：

 公共对象Convert（
对象值，类型targetType，对象参数，CultureInfo文化）
 {
对象的结果= null; 
 var path =字符串形式的值； 
 
 if（！string.IsNullOrEmpty（path）&& File.Exists（path））
 {
使用（var stream = File.OpenRead（path））
 {
 var image = new BitmapImage（）; 
 image.BeginInit（）; 
 image.CacheOption = BitmapCacheOption.OnLoad; 
 image.StreamSource =流; 
 image.EndInit（）; 
结果=图片； 
} 
} 
 
返回结果； 
} 
  

I have an image on my wpf page which opens an image file form hard disk. The XAML for defining the image is:

  <Image  Canvas.Left="65" Canvas.Top="5" Width="510" Height="255" Source="{Binding Path=ImageFileName}"  />

I am using Caliburn Micro and ImageFileName is updated with the name of file that image control should show.

When the image is opend by image control, I need to change the file. But the file is locked by image control and I can not delete or copy any mage over it. How can I force Image to close the file after it opened it or when I need to copy another file over it?

I checked and there is no CashOptio for image so I can not use it.

解决方案

You could use a binding converter like below that loads an image directly to memory cache by setting BitmapCacheOption.OnLoad. The file is loaded immediately and not locked afterwards.

<Image Source="{Binding ...,
                Converter={StaticResource local:StringToImageConverter}}"/>

The converter:

public class StringToImageConverter : IValueConverter
{
    public object Convert(
        object value, Type targetType, object parameter, CultureInfo culture)
    {
        object result = null;
        var path = value as string;

        if (!string.IsNullOrEmpty(path))
        {
            var image = new BitmapImage();
            image.BeginInit();
            image.CacheOption = BitmapCacheOption.OnLoad;
            image.UriSource = new Uri(path);
            image.EndInit();
            result = image;
        }

        return result;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

Even better, load the BitmapImage directly from a FileStream:

public object Convert(
    object value, Type targetType, object parameter, CultureInfo culture)
{
    object result = null;
    var path = value as string;

    if (!string.IsNullOrEmpty(path) && File.Exists(path))
    {
        using (var stream = File.OpenRead(path))
        {
            var image = new BitmapImage();
            image.BeginInit();
            image.CacheOption = BitmapCacheOption.OnLoad;
            image.StreamSource = stream;
            image.EndInit();
            result = image;
        }
    }

    return result;
}

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