How do I associate a filetype with an icon?

Question

I have written preview handlers for a couple custom file types. These file types don't have an application by default that can open them. I want to associate an icon with the file types as a signifier that they are custom.

I have tried setting a registry entry for DefaultIcon in HKCR\.<filetype>, but it doesnt appear to work, even after reboots. I do these registry modifications from C#, and the modifications are successful.

The icon file is simply an ico file residing in %APPDATA% for the moment. I plan to add a few more icons, and put these in a dll file. I just want to get it to work before I take those next steps.

How can I set this icon?

Looks like a duplicate of this: http://stackoverflow.com/questions/1203755/registering-file-type-and-custom-document-icon-in-net — Sanjamal, Dec 06 '11 at 21:31
I have already looked at that question. He appears to be getting his icons by associating the file type with a program. That is what I want to avoid. — Corey Larson, Dec 06 '11 at 21:33

score 6 · Accepted Answer · answered Dec 06 '11 at 21:36

6

Here is a simple .REG file that registers a icon for the file extension .tj

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.tj]

[HKEY_CLASSES_ROOT\.tj\DefaultIcon]
@="D:\\scratch\\testy\\icons\\tj.ico"

Tested on Win7

answered Dec 06 '11 at 21:36

John Knoeller

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That looks almost exactly like what I am doing. Are there any size, format constraints? Can the icon live in %appdata% if I give a fully qualified path? – Corey Larson Dec 07 '11 at 03:02
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I believe fully qualified path is necessary, I doubt that %appdata% would work because that translates to a different value for each user. – John Knoeller Dec 08 '11 at 20:19
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Doesn't work on Win10 – Mehdi Dehghani Aug 14 '22 at 14:13

score 1 · Answer 2 · answered Dec 06 '11 at 21:34

1

This MSDN article explains how to assign custom icons to file types

answered Dec 06 '11 at 21:34

Bhuvan

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That is what I initially followed to try and get it to work. What should I call from C# to do the `SHChangeNotify` function? Wouldn't a reboot do the same? – Corey Larson Dec 06 '11 at 21:37
Should work. However it needs absolute path of the icon as shown by John. Path references like %AppData% doesn't work. – Bhuvan Dec 06 '11 at 21:57
This MSDN doesn't work – Damien Aug 31 '22 at 09:48

How do I associate a filetype with an icon?

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