How to for plugin development

Updated 3 years ago

This documentation applies to plugins for 1.x only!

Documentation for 2.x+ is built into the Plugin Creator of Musescore.

( ⇒ In Musescore press Ctrl+Shift+P, then F1 to bring it up. )

Click here for Documentation for 3.x

A list of useful snippets for plugin creation.

Applying a function to each note of a selection

// Apply the given function to all notes in selection
// or, if nothing is selected, in the entire score
function applyToNotesInSelection(func) {
      if (typeof curScore === 'undefined')
            return;

      var cursor     = new Cursor(curScore);
      cursor.goToSelectionStart();
      var startStaff  = cursor.staff;
      cursor.goToSelectionEnd();
      var endStaff   = cursor.staff;
      var endTick    = cursor.tick() // if no selection, end of score
 
      if (cursor.eos()) { // no selection
            startStaff = 0; // start with 1st staff
            endStaff = curScore.staves; // and end with last
      }

      for (var staff = startStaff; staff < endStaff; ++staff) {
            for (var voice = 0; voice < 4; voice++) {          
                  cursor.goToSelectionStart(); // sets voice to 0
                  cursor.voice = voice; //voice has to be set after goTo
                  cursor.staff = staff;
                  if (cursor.eos())
                          cursor.rewind() // if no selection, beginning of score

                  while (cursor.tick() < endTick) {
                        if (cursor.isChord()) {
                              var chord = cursor.chord();
                              var n     = chord.notes;
                              for (var i = 0; i < n; i++) {
                                    var note   = chord.note(i);
                                    func(note);
                              }
                        }
                        cursor.next();
                  }
            }
      }
}

Calling an external process or a command line tool

Lilypond is called in this example. A plugin could also save as MusicXML, manipulate the MusicXML file and open it again via Score.load()

//---------------------------------------------------------
//    init
//    this function will be called on startup of mscore
//---------------------------------------------------------

function init()
      {
      }

//-------------------------------------------------------------------
//    run
//    this function will be called when activating the
//    plugin menu entry
//-------------------------------------------------------------------

function run()
      {
      // temp folder for user  C:\Users\<USERNAME>\AppData\Local\Temp on windows
      var path = QDir.tempPath(); // 
      var file = path + "/score.ly";
      curScore.save(file, "ly");
      
      //See http://doc.qt.nokia.com/latest/qprocess.html
      var lilypond = new QProcess();
      var args = new Array();
      args[0]= "-o";
      args[1]= path;
      args[2]= file;
      
      // if you want to log output
      //lilypond.setStandardOutputFile("stdout.txt");
      //lilypond.setStandardErrorFile("stderr.txt");

      lilypond.start("lilypond", args );
      lilypond.waitForStarted();
      lilypond.waitForFinished();
      }

//---------------------------------------------------------
//    menu:  defines were the function will be placed
//           in the MuseScore menu structure
//---------------------------------------------------------

var mscorePlugin = {
      menu: 'Plugins.Lilypond process',
      init: init,
      run:  run
      };

mscorePlugin;

Creating a GUI using Qt

You can access almost any class of the Qt Framework from the plugin framework
The easiest way to make a dialog or UI is to use Qt Creator. Qt Creator is installed with your version of Qt.

  1. Open Qt Creator
  2. File -> New File or Project -> Qt -> Qt Designer Form
  3. Create your form with the graphic interface. You may want to learn more about Layout Management in Qt
  4. Save your file as for example my.ui
  5. In your script use the following lines
  6. Signals and slots are a Qt concept. When a signal is fired (for example with a button is clicked), slots connected to it are executed. Slots can be define in your script to do something when something happens in the interface