无法修改Forms.ImageList.Images的集合键中的项目

Question

I'm using my first dotnet TreeView and I have a problem with ImageList Keys.

When I write this code :

int i;
i = MyIL.Images.Add(Properties.Resources.CheckedItemBitmap, Color.White);
MyIL.Images.Keys[i] = "Checked";

The key is not written. I mean that MyIL.Images.Keys[i] is still empty after that code. It looks like that it is read only. But the documentation says that one can set values in it.

This is a problem because I want to use this specific overloaded ImageList.Images.Add() function, that doesn't let me specify the key value.

This is not the end of the world, but any clue would be appreciated.

Answer 1

As you observed, according to the documentation , the Keys property is read-only. The key is normally something that is set when you add the item to the collection, and sure enough, there is an overload of Images.Add that accepts a custom key. So I would use that overload, and set the transparent colour in a separate call:

Properties.Resources.CheckedItemBitmap.MakeTransparent(Color.White);
MyIL.Images.Add("Checked", Properties.Resources.CheckedItemBitmap);