how to get app icon with name of the app

saber

i am in linux , qt 5.10.1

how can i get installed app icon from system with the app name??

ambershark

@saber I'm not sure I understand this entirely, but it sounds like you want to find the icon for an application based on the app name. So answering based on that.

In linux icons are associated with the application via .desktop files. So you would have something like this:

[Desktop Entry]
Name=Slack
Comment=Slack Desktop
GenericName=Slack Client for Linux
Exec=env LD_PRELOAD=/usr/lib/libcurl.so.3 /usr/bin/slack %U
Icon=slack
Type=Application
StartupNotify=true
Categories=GNOME;GTK;Network;InstantMessaging;
MimeType=x-scheme-handler/slack;

You can see here the application name is Slack and it's icon is set to slack. This slack.desktop file is located in the system default path of /usr/share/applications. If the icon does not have a path (as is this case with this one) it will look in /usr/share/pixmaps for it.

So if you wanted to find the icon you could grep through /usr/share/applications looking for the .desktop file associated with your application then find the Icon entry. However be aware that there are other places .desktop items can exist, like ~/.local/share/applications, so it's not a foolproof method.

Also apps in linux do not require a .desktop file to be run so there may not be one at all. In which case they won't have an icon associated with them and will get a default one.

Oh and not all window managers in linux use .desktop entries. The major ones like KDE and Gnome both do though.

saber

@ambershark

ok.got that .

i need to make function to get the icons .
i am on it.
thanks.

Devopia53

@saber

Have you ever tried this?

QFileInfo info("/home/myapplication");
QFileIconProvider   provider;
QIcon   icon = provider.icon(info);

saber

@Devopia53
sorry for late reply
i tried it . but not got any icon.

QFileInfo info("/usr/share/applications/Audacious");
    QFileIconProvider   provider;
    QIcon   icon = provider.icon(info);
    ui->start->setIcon(icon);

qDebug()<< info.isReadable(); is giving me false.But there is icon on that path.

JonB

@saber
So what does ls -l /usr/share/applications/Audacious show you?

saber

@JonB

ls: cannot access '/usr/share/applications/Audacious': No such file or directory

but there is the desktop file.

if this is not the way , how to do that properly?

JonB

@saber
So if that file doesn't exist you're not going to get anything good using it.

qDebug()<< info.isReadable(); is giving me false.But there is icon on that path.
...
but there is the desktop file.

What do you mean by "But there is icon on that path." ? Where is what desktop file?

What made you choose to write:
QFileInfo info("/usr/share/applications/Audacious");
?

JonB

@saber
Purely at a guess as to what you're trying to say, combined with what @Devopia53 is trying to suggest, I would say you need to do one of two things.

Find the .desktop file, which is a text file, and inspect it to see what icon file the desktop uses. Now, this may indeed by in /usr/share/applications, or perhaps ~/.local/share/..., but will be named with a .desktop suffix, e.g. perhaps /usr/share/applications/Audacious.desktop (be careful about capitalization under Linux). Use locate or find to search for suitable file names.
For @Devopia53's way, find the executable for Audacious. This will not be in /usr/share/applications, but perhaps in /usr/bin or maybe /usr/local/bin or elsewhere. Again use locate or find, or even which. Then try his code. However, personally I am unconvinced this will work under Linux where, unlike Windows, icons are not embedded in executables. But you could try. I think #1 will work instead.

ambershark

@JonB said in how to get app icon with name of the app:

However, personally I am unconvinced this will work under Linux where, unlike Windows, icons are not embedded in executables. But you could try. I think #1 will work instead.

Yea it definitely isn't going to work on linux. I even tested it to be sure since I was only about 95% sure it wouldn't work.

@saber Icons in linux are not set in the binaries. If you refer to my post above you'll find exactly how to deal with icons in linux. :)

QFileIconProvider will not work in linux. You will need to open the file (in your case /usr/share/applications/audacious.desktop) then read it for the Icon line. Keep in mind the Icon line is not guaranteed to be there since icons are not required in linux. Also note, you forgot the .desktop in your path above which is why the file was not found. Also, you used "Audacious" and on my file system it is lower case, i.e. audacious.desktop.

And the last thing to be aware of is the Icon entry can be something simple like in Audacious's case, it is:

Icon=audacious

There's no extension or path. This will look in /usr/share/pixmaps or other places like /usr/share/icons... which is the case for audacious:

/usr/share/icons/hicolor/48x48/apps/audacious.png
/usr/share/icons/hicolor/scalable/apps/audacious.svg

saber

@ambershark
yes understood the linux icon system.
just tried @Devopia53 code if i could find a short solution .

@JonB i also tried lower case app name .that gives me a UNKNOWN file icon.
in /usr/share/applications/ all the file name are in capital latter

also i tried this

    QString name = "chromium";
    QIcon   icon =  QIcon::fromTheme("applications-" + name.toLower());
    ui->start->setIcon(icon);

this should give me the icon but dose't .

this gives me the icon

    QString name = "chromium";
    QIcon   icon =  QIcon::fromTheme(name.toLower());
    ui->start->setIcon(icon);

but it gives me the icon not from default theme . it gives the icon from other installed theme.

JonB

@saber
Sorry, don't understand your problem now.

As both I & @ambershark have said, the file you need to look at should be at /usr/share/applications/audacious.desktop, exactly as that is written. It should be text file you can look at which will show you, in its Icon=... line, the path to the icon file used by the "Audacious" application. @ambershark has even shown you the content, naming a .png & a svg path for the icon file. Which I believe is exactly what you are looking for.

P.S. You wrote:

in /usr/share/applications/ all the file name are in capital latter

I think you'll find that's just whatever the application you're showing in your screenshot has chosen to display them as. Try ls /usr/share/applications if you want to know what the filenames actually are!

ambershark

@saber said in how to get app icon with name of the app:

/usr/share/applications/ all the file name are in capital latter

I would double check that whatever file manager you are using there isn't changing them to the names that are inside the .desktop file. I'm pretty sure it is. I've never seen something like Add/Remove Software.desktop on a linux file system. If nothing else using a path symbol (/) in a filename would be just begging for trouble.

My bet is if you do the ls /usr/share/applications they will be all (or at least mostly) in lowercase.

As for the QIcon::fromTheme stuff. I have no idea. I've never used it. It may work for you but from the sounds of it, it's not.

Here's a quick shell command to get the name of the icon file (sorry don't have time to write it up in Qt since I'm on my way out the door):

$ cat /usr/share/applications/audacious.desktop | grep Icon | gawk -F= '{ print($NF); }'
audacious

Then you could even link that to get you the actual filenames:

$ find /usr/share/icons -name "$(cat /usr/share/applications/audacious.desktop | grep Icon | gawk -F= '{ print($NF); }')*.png"
/usr/share/icons/hicolor/48x48/apps/audacious.png

There's a bit more to it than that since they could be full path names in the Icon in the desktop file or they could point to a place like /usr/share/pixmaps. But that's essentially it. You could even shell out to bash and use those commands if you were too lazy to use QFile to read it and find the icon file.

Either way, here's the solution in pseudocode:

Open filename /usr/share/applications/whatever.desktop
Read file looking for line starting with Icon=
Parse Icon= to get the filename
if filename is absolute or relative path
   return filename
else
   check /usr/share/icons/* for filename.* (image formats only here, like svg, png)
   if found
      return full path + filename
   else check /usr/share/pixmaps
   if found
       return full path + filename
return failure

Then once you get a filename, just open it and load it with QIcon.

JonB

@ambershark
Why would you go

cat /usr/share/applications/audacious.desktop | grep Icon

when you could just go

grep Icon /usr/share/applications/audacious.desktop

saving a process & a pipe?

Also, it's many years since I did an awk (I'm a perl man), but can't you just do for the whole thing:

gawk -F= '/^Icon/ { print($NF); }' /usr/share/applications/audacious.desktop

saving another process & pipe?

:)

ambershark

@JonB Lol you totally could. Using cat is an old habit of mine and I catch myself doing it all the time especially with grep... and same with grep. It could definitely all be done in gawk but usually when I do stuff like that it is to not have to spend time looking at command line help on something like gawk and just using what tool I know off the top of my head. :)

Edit: after I wrote this I was copying a file over ssh and throwing it through xz on both ends and I did: cat - | xz -dc - > images/win10-base-setup.qcow2, and immediately laughed when I saw I was using cat - again and only to use - in xz. The whole cat was completely useless. Made me laugh as I thought about this post figured I'd come show ya my bad cat habits in action. ;)

saber

here is the code

// get all the istalled theme
    QDirIterator it("/usr/share/icons", QDir::Dirs | QDir::NoDotAndDotDot);
    QStringList iconThemes;
    while (it.hasNext()) {
      it.next();
      iconThemes.append(it.fileName());
    }

// select the first icon theme from the iconThemes list.
// i is the app icon
QIcon i =QIcon::fromTheme(appName, QIcon::fromTheme(iconThemes.at(1);));

thanks