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I have 128x128 icon referenced in main window glade file like <property name="icon">../media/my-icon.svg</property>.

I tried, with both svg and png, but it is always very blurred in Ubuntu app switcher (Alt + Tab).

I noticed same when creating application from template using quickly, Ubuntu logo is very blurred as well.

Any idea why this might happen?

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1 Answer 1

up vote 8 down vote accepted

What's going on

The <property name="icon"> settings refers to the window icon, not the application icon. As I understand it, the Ubuntu windowing server (X.org) squashes these to a tiny size after loading. If you don't recall from year 2009, they used to be used in this capacity:

Picture of window icon

Using application icons instead

Ubuntu Unity will use this low-res format if needed. However it usually fetches application icons according to the Icon= value of a given window's application launcher, called a "desktop entry".

If you're a normal application developer who just plans to publish their program with the App Developer Portal, you can probably stop reading here. The free packaging service will handle writing your app's desktop entry and placing its installed icons in the right part of the filesystem. If not...

The nitty gritty

How to create a desktop entry and get Ubuntu to match your PyGTK window to the correct application icon and name is already documented in this question. But where do you actually place icons to get the right one displayed?

As it happens, the answer is fairly arcane. Per freedesktop.org specifications, icons are searched for and loaded by size, icon theme, and (when necessary) localization. Icons can even be installed in several difference prefixes depending on the source that installed them. Ubuntu "queries" icons by context.

The simple rules: use a unique icon name for your application to prevent false matches with other icons. Place the icon(s) for your application in one of the following directory (or a subdirectory thereof):

<user prefix>/share/icons/<icon width>x<icon height>/apps/
<user prefix>/share/icons/scalable/apps/

<user_prefix> is your application's install path (it will be /usr for packages installed by the package manager, /usr/local/ for other software installed for all users, and $HOME/.local for single-user installations). <icon width> and <icon height> (or 'scalable' for SVGs) refer to the dimensions of the icon. If you create many different icon resolutions, Ubuntu will always find and select the right one for any context.

Getting the right app icon to display while developing

  1. Create a scalable or high-resolution icon and place it in the correct subdirectory of your user home's share/ directory. For example, myapp.svg would go in $HOME/.local/share/icons/scalable/

  2. Write a desktop entry that includes the non-extensioned name of your icon. For example

    [Desktop Entry]
    
    Name=My Application
    Exec=my_binary
    Icon=myapp
    

    Place this in $HOME/.local/share/applications/. Note that my_binary must be an executable searchable in one of your $PATH directories.

  3. Run your application either (a) from the Unity Dash, (b) from the command line using the exact name of your $PATH executable [eg 'my_binary'].

If that all reads like gibberish...

Open your file browser and explore the directories /usr/share/applications/ and /usr/share/icons/. Look around and you'll catch on to how application metadata and icons work in Ubuntu.

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Awesomely detailed answer! –  Thomas Boxley Dec 31 '11 at 8:43
    
Thank you very much, this is the best answer I ever get on stack! But, since I am ubuntu app/python dev newbie, and coming from different dev world, I don't know many things regarding packaging, conventions...some things you mentioned I know already. So, what happened, I wanted to run setup.py and install app, hoping blurred icon will be fixed. But what happened is icon simply disappeared, now I get question mark icon. Then I tried to fix it with hard-coding Icon= to absolute path to my svg icon, but problem resists. What should I do in order to get icon showed properly while I'm developing? –  umpirsky Jan 1 '12 at 16:00
1  
@umpirsky I've added a new section to my answer that should hopefully spell it out. –  Jjed Jan 1 '12 at 20:25
    
@j-johan-edwards Thanks a lot. So, there is no way to implement this in one directory, not using $HOME/.local/share/icons/scalable/ and $HOME/.local/share/applications/? Anyway, I tried what you suggested, and still no icon. Note that in $HOME/.local/share/applications/there were only wine-extension desktop files, other apps are probably somewhere else. Also, there was no $HOME/.local/share/icons/scalable/, but I created it and placed icon inside, but still no icon when I run app (from Unity launcher this time). –  umpirsky Jan 1 '12 at 20:59

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