gimp/debian

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Controlling GIMP with MIDI devices
How To © 2005 Simon Budig. Licensed under the terms of the GNU GPL.

Retrieved from <http://www.gimp.org/unix/howtos/gimp-midi.html>
by Ari Pollak <ari@debian.org> on 6 Apr 2005.
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What?
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GIMP comes with a module that allows to control it using MIDI devices.
Currently this is only supported on Linux with either the OSS or the ALSA sound
drivers. It might work on other platforms as well if there is a way to access
the raw MIDI stream by opening a device.


Enabling the MIDI Module
------------------------

To make the UI of Gimp's MIDI controller visible you need to edit a
configuration file when the Gimp is not running. Open ~/.gimp-2.6/controllerrc
in an editor and add the following lines to the end of the file:

(GimpControllerInfo "MIDI"
    (enabled yes)
    (debug-events yes)
    (controller "ControllerMidi"
        (device "alsa")
        (channel -1))
    (mapping))

Then start the GIMP from a shell (so that you can see textual output we need
later), open the preferences, go to the "Input Controllers" page in the "Input
Devices" section and select the newly appeared "MIDI" Tab.


Configuring the MIDI Source
---------------------------

ALSA:
Enter "alsa" in the "Device" entry in the configuration. Gimp then sets up an
Alsa-Output-Port (check with "aconnect -lo"). You can then use your preferred
tool to configure Alsa to connect a MIDI source to the GIMP. When your MIDI
device e.g. provides an Input-Port 72:0 and Gimp provides the Output-Port 128:0
you can connect the two Ports with "aconnect 72:0 128:0".

OSS:
The Open Sound System provides a device file for the raw MIDI events. You need
to enter the name of this device file into the "Device" entry in the
configuration (e.g. "/dev/midi00").

The MIDI channel:
Each MIDI source sends events on a specific "Channel" (0 to 15, sometimes also
referred as 1 to 16). You can configure if Gimp should listen to all channels
(-1) or to just a specific channel.

If your MIDI setup works correctly and the "Dump events from this controller"
is enabled as well as "Enable this controller" you should see some text
scrolling by when you hit some keys or turn some controllers on your midi
device, describing the Event that just happened.


Assigning Actions to Events
---------------------------

You can now use this information to map MIDI Events to Actions in the Gimp. At
the bottom of the configuration page is a list with all events that Gimp can
recognize. Scroll to the event that you want to assign an action to and
doubleclick its entry. Then select an Action from the dialog that pops up and
doubleclick its entry. Now this action gets invoked when the specific MIDI
event happens.

Please note that some actions fit perfectly to some MIDI Events: Actions like
"context-background-blue-set" can immediately use the numerical value provided
by midi controller events.

Have fun.