Changing system preferences programmatically

Wednesday, June 17th, 2009

My very first post on this blog showed how to change Matlab’s command-window colors. In that post I promised to write another post detailing how system preferences can be changed from the command line.

Last week I wrote about undocumented GUIDE features. After my initial post, I realized that I forgot to mention all the different relevant system preferences that can also be modified. I therefore modified last week’s post with the preferences information. I now wish to finally detail how such preferences can be changed programmatically, from within your Matlab application or from the Matlab desktop command prompt.

Matlab’s user preferences are stored in the matlab.prf text file which is stored in the user’s Matlab preferences folder:

edit(fullfile(prefdir,'matlab.prf'));

Each preference appears to be on a separate line in the following format: <pref-name>=<pref-type><pref-value>

where <pref-type> appears to be one of these:

  • ‘B’ => boolean/logical flag
  • ‘C’ => color (RGB numeric value)
  • ‘F’ => font (type,size,name)
  • ‘I’ => int16
  • ‘J’ => int64
  • ‘R’ => rectangular area (x,y,h,w)
  • ‘S’ => string/char

Examples:
    EditorShowLineNumbers=Btrue
    EditorMaxCommentWidth=I120

You can read the preference names from this matlab.prf file and then use the following (you-guessed-it) java calls to get/set the values:

com.mathworks.services.Prefs.get<type>Pref(<pref-name>)
com.mathworks.services.Prefs.set<type>Pref(<pref-name>, newValue);

where <type> is one of: Boolean, Color, RGBColor, Font, Integer, Rectangle, String, Double (I believe Doubles get converted to int64 – possibly a bitwise casting since both use 64 bits)

For example:

com.mathworks.services.Prefs.getBooleanPref('LayoutSnapToGrid')
com.mathworks.services.Prefs.setIntegerPref('LayoutGridWidth', 25)

adding a second argument to get<type>Pref() appears to indicate a default value that is returned if <pref-name> is not defined:

com.mathworks.services.Prefs.getIntegerPref('xxxx',123)
=> 123

We can programmatically set any preference key we like – we are not limited to Matlab’s built-in set. I used this feature in my CPRINTF utility, to set user-defined colors for later use by the desktop’s UI syntax-highlighting engine. The relevant code segment is this:

% Convert a Matlab RGB vector into a known style name (e.g., '[255,37,0]')
function styleName = getColorStyle(rgb)
 
  % Convert Matlab RGB array into a Java Color object
  intColor = int32(rgb*255);
  javaColor = java.awt.Color(intColor(1), intColor(2), intColor(3));
 
  % Preference key name format: '[RRR,GGG,BBB]'
  styleName = sprintf('[%d,%d,%d]',intColor);
 
  % Set/update the preference with this Java Color
  com.mathworks.services.Prefs.setColorPref(styleName,javaColor);

…which in turn adds entries such as the following to my matlab.prf file:
    [12,34,67]=C-15982013

Note that -15982013 = 0xFF0C2243, which is the RGB value [12,34,67] with an opaque alpha value. This value can later be retrieved using:

>> com.mathworks.services.Prefs.getColorPref('[12,34,67]')
ans =
java.awt.Color[r=12,g=34,b=67]

Warning: I published much of this information on the CSSM forum back in 2007. Ben Steiner then shared his experience on that thread that:

For anyone else that’s playing with this: I don’t advise trying to edit the matlab.prf via matlab(!). I created a situation that made Matlab unworkable. I did find that deleting the matlab.prf completely (in frustration) solved it.

Take a look at your matlab.prf file – can you spot any interesting preference? If so, please share it in the comments section below.

Related posts:

  1. Non-textual editor actions – The UIINSPECT utility can be used to expand EditorMacro capabilities to non-text-insertion actions. This is how:...
  2. R2009b keyboard bindings – The new Matlab release R2009b includes the ability to customize keyboard bindings for the editor and Command Window. However, there are still some uses for the EditorMacro utility and its variants....
  3. Accessing the Matlab Editor – The Matlab Editor can be accessed programmatically, for a wide variety of possible uses - this article shows how....
  4. Customizing help popup contents – The built-in HelpPopup, available since Matlab R2007b, has a back-door that enables displaying arbitrary text, HTML and URL web-pages....
  5. Customizing Workspace context-menu – Matlab's Workspace table context-menu can be configured with user-defined actions - this article explains how....
  6. Programmatic shortcuts manipulation – part 2 – Non-standard shortcut controls and customizations can easily be added to the Matlab desktop. ...
Categories: Desktop, High risk of breaking in future versions, Java

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14 Responses to Changing system preferences programmatically

  1. Pingback: Undocumented feature() function | Undocumented Matlab

  2. Shaul says:
    February 2, 2011 at 8:07 am

    Hi Yair,

    I work on multiple projects at the same time and I like to have multiple matlab instances open on my computer, one for each project (I realize this might not be a particularly smart way to work). However, I would like each of them to save to a different command window history file. Is there a good safe way to do this?

    Thanks! All the best,
    Shaul

    Reply
  3. Paul says:
    May 25, 2011 at 1:33 pm

    Is there a way to programmatically update the Simulink preferences, such as the Autosave option?

    Thanks,

    paul

    Reply
  4. Chad Gilbert says:
    January 10, 2012 at 12:13 pm

    Hi Yair,

    It seems that after doign this, I need to re-start MATLAB before the changes take effect. Do you know of any better way to make my changes “kick in”?

    Reply
    • Yair Altman says:
      January 10, 2012 at 12:56 pm

      @Chad – there is a com.mathworks.services.Prefs.load() method, but I think it will not help you much because I think that most preferences are loaded and used during startup, not dynamically.

  5. Jonas says:
    November 14, 2012 at 3:56 pm

    I just learned once more that it’s extremely helpful to programmatically check for the correct “MatfileSaveFormat” property to avoid being unable to save (or later: load) your results. Thanks for your helpful post!

    Reply
  6. Oleg Komarov says:
    October 13, 2014 at 3:08 am

    To change Parallel Pool settings:

    ps = parallel.Settings;
ps.Pool
ans = 
  PoolSettings with properties:
                            AutoCreate: 0
                RestartOnClusterChange: 1
    RestartOnPreferredNumWorkersChange: 1
                           IdleTimeout: 30
                   PreferredNumWorkers: 12
    Reply
    • Yair Altman says:
      October 13, 2014 at 4:24 am

      To complete the picture:

      >> ps = parallel.Settings
ps = 
 Parallel Settings Information
       DefaultProfile: local
 
    Profiles and Components: 
 
             Profiles: [1x1 parallel.settings.Profile]
  SchedulerComponents: [1x1 parallel.settings.schedulerComponent.Local]
    ProjectComponents: [0x0 parallel.settings.ProjectComponent]
 
>> getundoc(ps)
ans = 
            ConfigsMcrUserDataKey: 'ParallelConfigurationFile'
    ConfigurationsLastUpgradeTime: '???'
    DefaultProfileChangedListener: [1x1 event.proplistener]
          DefaultProfileListeners: [1x2 event.listener]
             DefaultProfileObject: [1x1 parallel.settings.Profile]
           DummyEnforceInitClient: 'BMPA'
                 ImportNameSuffix: '_Import'
         LastUpgradeSettingsLevel: [1x1 parallel.internal.types.SettingsLevel]
                 LocalProfileName: 'local'
            McrUserDataNameSuffix: '_mcruserdata'
                       NodeFacade: [1x1 parallel.internal.settings.SettingsNodeFacade]
                             Pool: [1x1 parallel.internal.settings.PoolSettings]
               ProfilesCollection: [1x1 parallel.internal.settings.NamedNodesCollection]
           ProfilesMcrUserDataKey: 'ParallelProfile'
      ProjectComponentsCollection: [1x1 parallel.internal.settings.NamedNodesCollection]
    SchedulerComponentsCollection: [1x1 parallel.internal.settings.TypedNodesCollection]
         UsingDeployedCollections: 0
  7. Scott Lowe says:
    November 8, 2015 at 9:00 pm

    Hi Yair,

    Thanks for this article!

    I took inspiration from it to create a package to import and export color schemes in MATLAB. This definitely would not have been possible without undocumentedmatlab!

    It is available on GitHub and FileExchange.

    All the best,
    Scott

    Reply
  8. jon says:
    May 13, 2016 at 8:06 pm

    Thank you!

    Reply
  9. Parvaneh says:
    September 28, 2016 at 1:59 pm

    Hi Yair,

    I was looking for a way to change the setting of the system using matlab when I saw this post.
    I wonder if you can help me with it.
    I’m connecting two monitors and I want to run a program from one monitor and make it run on the other one.
    In the process I need to change setting from ‘screen resolution’ in the control panel.
    Could this be done with matlab?

    I would appreciate any help.

    Thanks,
    Parvaneh

    Reply
    • Yair Altman says:
      September 28, 2016 at 2:09 pm

      @Parvaneh – you will need to check the web for a utility that has a command-line interface that does what you want, and then you can call that utility from Matlab using the system command.

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