Where to find Icon in .desktop file mantioned without path?

Question

Here is an example for Hydrogen Drum Machine

[Desktop Entry]
X-AppInstall-Package=hydrogen
X-AppInstall-Popcon=208
X-AppInstall-Section=universe

Name=Hydrogen
Comment=Create drum sequences

GenericName=Drum Machine

Version=1.0

Type=Application
Categories=AudioVideo;Audio;Qt;

MimeType=text/xml;

Exec=hydrogen %F
TryExec=hydrogen
Terminal=false
StartupNotify=true

Icon=h2-icon

X-Ubuntu-Gettext-Domain=app-install-data

But I can not find anywhere the icon.

The same with Atom IDE or other software. Where they store their icons? I don't want search through ** all the time a need an icon >_<

Answer 1

The question is almost a dupe of this one, and this one is also useful to read, but for reasons of findability, I will post an answer here.

How to find installed files of your application

for globally installed applications, by default, icons in /usr/share/pixmaps do not need the path, and if you do not use their path in a .desktop file, you must not use their extension as well.

In this case however, that is not the case, as you can see in the output of

dpkg-query -L hydrogen

which shows you where the icon is located.

from man dpkg:

   dpkg-query actions
       ------------------

      -L, --listfiles package-name...
          List files installed to your system from package-name.

Then:

$ dpkg-query -L hydrogen | grep h2-icon

returns:

/usr/share/hydrogen/data/img/gray/h2-icon.svg
/usr/share/icons/hicolor/scalable/apps/h2-icon.svg

Either one of these two is your icon. My guess is that it is the second one :).