在C＃中添加到ImageList时，Image.Tag为null

Question

I have the following code which reads a image from a Url and adds the image to a ImageList.

WebClient oWebClient = new WebClient();
Uri oUri = new Uri("http://www.mysite.com/images/image1.jpg");

try
{
    Image oImage = Image.FromStream(oWebClient.OpenRead(oUri));
    oImage.Tag = "hello World";
    imageList1.Images.Add("test", oImage);
}
catch(Exception ex)
{
    listBox1.Items.Add("Error getting photo: " + ex.Message);
}

Everything works fine, except for some reason the Image tag is empty when I inspect it in the imageList1 object ? Why is this happening ?

Answer 1

I would steer away from using the Tag property on objects, as it can be unreliable (as you see) as well as not being very extensible.

In your case ImageList.Add(key, image) uses the key parameter is so you can retrieve that Image later using ImageList[key] indexer property.

If you are trying to store more data into the Tag property, I would recommend you instead create your own data model class and use that instead.

It is much easier to keep a List<T> or Dictionary<Key, Value> of your type for retrieval instead of playing with Tag casting/lookup.