How do I add the go language to gitg's list of viewable sources?

Question

Hoping a 'git' guru will help out here.

I am just beginning to "git" for the first time and have (among other things :-) ) git and gitg installed from Ubuntu 10.4 / AMD64 distribution (ie. maybe not 'latest' version but not ancient).

I am trying to look at the go code I've committed via gitg and in the "tree tab" it says:

Cannot display file content as text.

However, the "details tab" shows the diffs of the same file just fine.
I know gitg's "tree tab" is working because I can use the tree view on *.c / *.html / *.txt, etc just fine.

<question> Is there a way to tweak gitg into understanding that "*.go" is just text? </question>

A little more context:

• Installed gitg version is 0.0.5 - ie a version behind latest - 0.0.6 - source of which I am looking thru now.

I do have a working /usr/share/gtksourceview-2.0/language-specs/go.lang.
It works just fine as highlighter in gedit.
It appears that gitg may require displayable files to have a mime type of "text/plain", so I added that to go.lang

No joy. gitg still fails on *.go.
I'm relatively sure the fix is simple, just don't know where to look.

Answer 1

When it comes to gitg (the git repository viewer targeting gtk+/GNOME), it may be interesting to look at its code (also here):

In particular, gitg-commit-view.c displays that message because its function gitg_utils_can_display_content_type() return an unknown type for text display purposes.

gboolean
gitg_utils_can_display_content_type(gchar const *content_type)
{
        return g_content_type_is_a(content_type, "text/plain") || 
                   g_content_type_equals(content_type, "application/octet-stream");
}

So you do need to declare go file type as text/plain (in gitg, not "to go.lang") and it should work.

---

Actually, the declaration is not in gitg: g_content_type_is_a is a function of glib\gio\gcontenttype.c (project glib), and it calls get_registry_classes_key(), which read the registry (HKEY_CLASSES_ROOT for Windows, mime type registered for Unix).

So if you register the go files, it should work:

xdg-icon-resource install --context mimetypes --size 48 go-type.png plain/text

The xml file to register (found by the OP Hotei, great work!)

<?xml version="1.0" encoding="utf-8"?>
<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info"&gt;
  <mime-type type="application/x-extension-go">
    <sub-class-of type="text/plain"/>
    <comment>go for files</comment>
    <glob pattern="*.go"/>
  </mime-type>
</mime-info>

xdg-mime install go-mime.xml
update-desktop-database