Processing 1.0 - Processing Discourse - RemoveEvent in ProMIDI

Reverb Rick

RemoveEvent in ProMIDI
Jun 25^th, 2008, 1:15pm

Hi there,
I am new to promidi and I'd like to make a kind of step sequencer. I am creating notes when someone toggles a button:
track.addEvent(new Note(35+row,127,30),col-1);
and when someone is turning off the button I'd like to remove this note/event and this is where my problem pops up:
track.removeEvent(???,col-1);
I do not know what to put as a first parameter....
Please help!

Regards
Reverb Rick

RR

JohnG Ex Member	Re: RemoveEvent in ProMIDI Reply #1 - Jun 25^th, 2008, 2:22pm This is purely a guess,having not used the library, but the standard way would be: Code: Note n=new Note(35+row,127,30); track.addEvent(n,col-1); track.removeEvent(n,col-1);

Reverb Rick YaBB Newbies Offline Posts: 5	Re: RemoveEvent in ProMIDI Reply #2 - Jun 25^th, 2008, 3:24pm Great! It will work! Thank you very much! RR
	RR

Reverb Rick

Re: RemoveEvent in ProMIDI
Reply #3 - Jun 26^th, 2008, 9:05am

I'm still to weak to complete that one :(
Your advice works if I know the name of variable defined.
To track which one to switch off I've created an array:
Note[] n = new Note[255];
and then:
track.addEvent(n[id],col-1);
...
track.removeEvent(n[id],col-1);
...
which produces:

ERROR. an error occured while forwarding a Controller value
to a method in your program. please check your code for any
possible errors that might occur in this method .
e.g. check for casting errors, possible nullpointers, array overflows ... .
method: controlEvent
exception: java.lang.reflect.InvocationTargetException

...looks like array overflow, but dont know why...

Please help!

RR

JohnG Ex Member	Re: RemoveEvent in ProMIDI Reply #4 - Jun 26^th, 2008, 9:52am You'll have to show a bit more code for us to be able to help. It's possible you've not initialised the n[id] and so are sending a null in to the function...

Reverb Rick YaBB Newbies Offline Posts: 5	Re: RemoveEvent in ProMIDI Reply #5 - Jun 26^th, 2008, 10:16am Many thanks for a quick response! the code looks like that: Note[] n = new Note[255]; .... if(valu==1.0){ n[id] = new Note(35+row,127,30); track.addEvent(n[id],col-1); } else{ track.removeEvent(n[id],col-1); } .... the id is a number of step of my sequencer
	RR

eranhill YaBB Newbies Offline Posts: 4	Re: RemoveEvent in ProMIDI Reply #6 - Dec 24^th, 2008, 6:56am hey there, im having the exact same problam. cant remove Event. did you come up with something?

Reverb Rick YaBB Newbies Offline Posts: 5	Re: RemoveEvent in ProMIDI Reply #7 - Dec 24^th, 2008, 11:52am nope...it was thrown to a drawer. Hope I'll come back to that with a king of fresh mind. Hope you'll succeed! RR
	RR

eranhill YaBB Newbies Offline Posts: 4	Re: RemoveEvent in ProMIDI Reply #8 - Dec 24^th, 2008, 3:50pm oh my... i have a large project stuck on this bit. i get a 'NullPointerException' when i try removeEvent. anyway thanks for your replay, i hope someone will have a solution.

Moe

Re: RemoveEvent in ProMIDI
Reply #9 - Feb 16^th, 2009, 10:38pm

Hi.. I was having some problems with this as well. I'm not sure I can tell exactly why your code isn't working but I have two working examples. I've written one step-sequencer using an array for storing the events and one that doesn't use MIDI-events at all (it does use notes Wink

but it doesn't add() and remove() them). Both ways work, so try them both!

The Array way:

MidiEvent[] buttonEvents;

//in void setup(){

buttonEvents = new MidiEvent[16]; //Storing the "active" events of one bar.

//in void mousePressed(){

for(int i = 0 ; i < 16 ; i++){
if(buttons[i].isOver()){ //if I press the mouse when over a button
if(buttons[i].isPressed()){ //and the button is already pressed,
//then the active event will be removed
track.removeEvent(buttonEvents[i],i);
//the second argument to removeEvent() could be anything, really.
}else{ //It depends on what number of ticks you have chosen
// for your sequencer - in this case 16.
//if the mouse is clicked when over a button that is not already pressed:
// we save a Note in the buttonEvents-array,

buttonEvents[i+16] = new Note(60, 20, 2);

// and add it to the track, at tick i.

track.addEvent(buttonEvents[i],i);
}
}
}

Moe

Re: RemoveEvent in ProMIDI
Reply #10 - Feb 16^th, 2009, 10:52pm

Oh, and my second example:

//this program doesn't use a track to send MIDI-events,
//but rather just sends notes whenever the sequencer
//"lands" on a trigger - in this case steps in a step-
//sequencer. The code below is taken from a class called Buttons.

//in constructor:
int tempTick = 0
Button[] buttons; //the class uses an array of another class:
//clickable two-state buttons with a method isPressed() that returns
//what state the button is in.
buttons = new Button[16];
//

void sendMidi(){ //this is a method of a class of buttons.

//the variable b is used to store the position of the sequencer:
int b = int(sequencer.getTickPosition() % 16);
if(b != tempTick){ //this only happens once every tick.

//if the button corresponding to the current tick is pressed...
if(buttons[b].isPressed()){
// we send a note.
Note note = new Note(36,120,20);
midiOut.sendNote(note);
}
}
}
tempTick = b; //we set the tempTick to be the current tick.
}

//this last bit is from void draw()

if(sequencer.isRunning()){
boxes.sendMidi();
}

Moe

Re: RemoveEvent in ProMIDI
Reply #11 - Feb 16^th, 2009, 11:07pm

oh..

and the problem in the code you posted is probably that you're not referring to a specific MIDI-event. For the program to remove a MIDI-event from the track, you have to tell it exactly which event to remove. For example,

track.addEvent(Note(1,1,1),1);
//followed by
track.removeEvent(Note(1,1,1),1);

probably wouldn't work (I haven't actually tested this, but I don't think it works), because even if the notes look the same, they are not the exact same Note.

And in,

track.removeEvent(n[id],col-1);

I would rather use an int than the expression "col-1" - to remove an event you have to tell the track exactly at which tick it is scheduled, and by giving removeEvent() a variable you risk giving it an empty tick.

Also, it is very important that the event n[id] have been explicitly defined earlier in your code. In the code...

if(valu==1.0){
n[id] = new Note(35+row,127,30);
track.addEvent(n[id],col-1);
}
else{
track.removeEvent(n[id],col-1);
}

...you are clearly taking the risk of removing an event that doesn't exist.

God, this became a quite long answer but I hope it helps. And I hope you get the sequencer up and running! Good luck!

Moe.

giair

Re: RemoveEvent in ProMIDI
Reply #12 - Feb 2^nd, 2010, 1:47am

I've the same problem. I don't undersand why I can't remove notes.
If someone could help me.

The idea here is very simple.
-Create an array of 4 notes
-Delete each notes one by one with "DELETE" keyCode
- Another solution would be with '1', '2', '3', '4' keys but it doesn't work too.

Code:


/* *PROMIDI SEQUENCER * */

import promidi.*;

// DECLARATIONS PROMIDI
MidiIO midiIO;
MidiOut midiOut;
Sequencer sequencer;
Track track;
Note [] notes;
int counterDelete = 0;

void setup(){
 
  // MIDI IN OUT 
  MidiIO midiIO = MidiIO.getInstance();
  midiIO.printDevices();
  midiIO.closeOutput(1);
  MidiOut midiOut = midiIO.getMidiOut(1,1);

  // TRACK
  track = new Track("one", midiOut);
  track.setQuantization(Q._1_4);
  
  // NOTES > TRACK
  notes = new Note[4];
  notes[0] = new Note(36,90,100);
  notes[1] = new Note(41,90,100);
  notes[2] = new Note(46,90,100);
  notes[3] = new Note(48,90,100);
  
  track.addEvent(notes[0], 0);
  track.addEvent(notes[1], 1);
  track.addEvent(notes[2], 2);
  track.addEvent(notes[3], 3);

  // SONG
  Song song = new Song("midiOut", 120);
  song.addTrack(track);
  
  // SEQUENCER
  sequencer = new Sequencer();
  sequencer.setSong(song);
  sequencer.setLoopStartPoint(0);
  sequencer.setLoopEndPoint(512);
  sequencer.setLoopCount(-1);
}

void mousePressed(){
  if(mouseButton == LEFT) sequencer.start();
  else sequencer.stop();
}

void keyPressed() {
  if (key == DELETE) {
   track.removeEvent(notes[counterDelete], counterDelete);
   println("DELETE " + counterDelete); 
   counterDelete ++;
  }

// Another solution :
//  if (key == '1') track.removeEvent(notes[0], 0);
//  else if (key == '2') track.removeEvent(notes[1], 1);
//  else if (key == '3') track.removeEvent(notes[2], 2);
//  else if (key == '4') track.removeEvent(notes[3], 3);
}

void draw(){}

Quite simple, isn't it ?

But It does'nt work at all Sad

The message error concern ticks greater than the first tick I guess.
The first note is deleted and the second stop the programm and display this message :

Exception in thread "Animation Thread" java.lang.NullPointerException
at promidi.TickMapEvents.removeEvent(TickMapEvents.java:85)
at promidi.Pattern.removeEvent(Pattern.java:503)
at proMidi_sequencer.keyPressed(proMidi_sequencer.java:74)
at processing.core.PApplet.handleKeyEvent(PApplet.java:1752)
at processing.core.PApplet.dequeueKeyEvents(PApplet.java:1735)
at processing.core.PApplet.handleDraw(PApplet.java:1437)
at processing.core.PApplet.run(PApplet.java:1327)
at java.lang.Thread.run(Thread.java:619)

Any help ?

cjroads YaBB Newbies Offline Posts: 1	Re: RemoveEvent in ProMIDI Reply #13 - Feb 2^nd, 2010, 7:28pm Great info. It really makes sense. Thanks! Problem solved.
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