为什么 BitmapImage RequestCachePolicy 被忽略？

发布于 2024-10-19 06:11:37 字数 680 浏览 5 评论 0原文

我发现在 BitmapImage 上设置 RequestCachePolicy 属性对于 Image 的 Source 时如何下载位图没有影响 设置为 BitmapImage 的此实例。

例如，如果我将 RequestCachePolicy 设置为 CacheOnly，我希望不会发生任何互联网流量 - 指定的图像只能从缓存中检索。但相反，我看到向服务器发出下载图像的请求：

source = new BitmapImage(bmi.UriSource, 
  new RequestCachePolicy(RequestCacheLevel.CacheOnly));
// An image gets downloaded!

如果我在 HttpWebRequest 上设置静态 DefaultCachePolicy 属性，那么我的应用程序行为会以我想要的方式发生变化。会期望。即当它设置为CacheOnly时，不会发生网络流量。

为什么 BitmapImage 上的 RequestCachePolicy 属性没有达到我预期的效果？

原文

I'm finding that setting the RequestCachePolicy property on BitmapImage has no effect on how the bitmap is downloaded when an Image's Source is set to this instance of BitmapImage.

For example, if I set the RequestCachePolicy to CacheOnly, I would expect no internet traffic to occur whatsoever - the specified image should only be retrieved from the cache. But instead, I see a request being made to the server to download an image:

source = new BitmapImage(bmi.UriSource, 
  new RequestCachePolicy(RequestCacheLevel.CacheOnly));
// An image gets downloaded!

If I set the static DefaultCachePolicy property on HttpWebRequest, then my application behaviour changes in a way I would expect. ie when it's set to CacheOnly, no network traffic occurs.

Why is the RequestCachePolicy property on BitmapImage not having the effect I expect?

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