Image PropertyItems和disposStream

本文介绍了Image PropertyItems和disposStream的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在使用 MemoryStream从 byte [] 加载 Image 并通过检查图像的 ProperyItems 获取有关图像的信息。在这样做的过程中，我注意到一些奇怪的行为，其中一些图像的 PropertyItems 正在消失。经过大量调试后，我终于发现这是由于 MemoryStream 被处理造成的。

I'm loading an Image from a byte[] using MemoryStream and getting information about the image by inspecting it's ProperyItems. In the process of doing this though, I noticed some odd behaviour where some of the image's PropertyItems were disappearing. After much debugging I finally figured out that this was being caused by the MemoryStream being disposed.

MemoryStream ms0 = new MemoryStream(imageBytes);
Image img0 = Image.FromStream(ms0);
Console.Out.WriteLine("Without using, Image propertyIDs: ");
foreach (int itemId in img0.PropertyIdList)
    Console.Out.Write(itemId + ", ");
Console.Out.Write("\n");

Image img1 = null;
using (MemoryStream ms1 = new MemoryStream(imageBytes))
{
    img1 = Image.FromStream(ms1);
}
Console.Out.WriteLine("Outside using, Image propertyIDs: ");
foreach (int itemId in img1.PropertyIdList)
    Console.Out.Write(itemId + ", ");
Console.Out.Write("\n");

输出：

Without using, Image propertyIDs:
254, 256, 257, 258, 259, 262, 269, 273, 274, 277, 278, 279, 282, 283, 284, 296,
Outside using, Image propertyIDs:
254, 256, 257, 258, 259, 262, 274, 277, 278, 284, 296,

所以看来至少有一些 PropertyItems 由 MemoryStream的内容直接支持并且解决方案是不处理它，或者我错了？

So it appears that at least some of the PropertyItems are directly backed by the contents of the MemoryStream and the solution is not to dispose it, or am I wrong?

在调试此问题的过程中我注意到了其他问题奇怪，如果我在中访问 PropertyIdList （或与图像 PropertyItems 相关的任何内容）在 MemoryStream 被处理后，使用块， PropertyItems 不会消失。

In the process of debugging this issue though I've noticed something else odd, if I access the PropertyIdList (or anything related to the images PropertyItems) inside the using block, the PropertyItems won't disappear after the MemoryStream is disposed.

Image img2 = null;
using (MemoryStream ms2 = new MemoryStream(imageBytes))
{
    img2 = Image.FromStream(ms2);
    int[] tmp = img2.PropertyIdList;
}
Console.Out.WriteLine("Outside using with PropertyIdList access, Image propertyIDs: ");
foreach (int itemId in img2.PropertyIdList)
    Console.Out.Write(itemId + ", ");
Console.Out.Write("\n");

输出：

Outside using with PropertyIdList access, Image propertyIDs:
254, 256, 257, 258, 259, 262, 269, 273, 274, 277, 278, 279, 282, 283, 284, 296,

我查看了图像的来源class和 PropertyIdList 属性似乎没有保留 PropertyItems 数据的本地副本，那么为什么 PropertyItems 在这种情况下处理 MemoryStream 后保留？

I looked at the source for the Image class and the PropertyIdList property doesn't appear to be retaining a local copy of the PropertyItems data, so why are the PropertyItems retained after the MemoryStream is disposed in this situation?

PropertyItems

Image PropertyItems和disposStream

问题描述

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