After creating a custom [1] keyboard layout with Ukelele, I wanted it to match the original layout's icon. It turns out that OS X stores the country flags in /System/Library/Keyboard Layouts/AppleKeyboardLayouts.bundle/Contents/Resources/AppleKeyboardLayouts-L.dat.

I don't know the exact structure of that file, but the icons are simply there (look for icns in hex, i.e. 0x69636e73).

apple-kbd-dat-icon-extract.py is a quick and dirty script the exracts the icons (icns files) from the above file and writes them to the specified output directory.

[1] Not really custom. OS X doesn't support the БДС 5237-2005 Bulgarian phonetic layout (GNU/Linux does).

% mkdir /tmp/icons
% ./apple-kbd-dat-icon-extract.py -o /tmp/icons
./apple-kbd-dat-icon-extract.py: Reading /System/Library/Keyboard Layouts/AppleKeyboardLayouts.bundle/Contents/Resources/AppleKeyboardLayouts-L.dat
./apple-kbd-dat-icon-extract.py: Writing icon file /tmp/icons/icon1.icns
./apple-kbd-dat-icon-extract.py: Writing icon file /tmp/icons/icon2.icns
./apple-kbd-dat-icon-extract.py: Writing icon file /tmp/icons/icon3.icns
...
./apple-kbd-dat-icon-extract.py: Writing icon file /tmp/icons/icon132.icns
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