How to detect 3 key presses in SWT KeyListener

Question

As of now i am using below code to detect two key presses. I.e, Ctrl+F(or) Shift+1...Etc,

 CCombo comboBox = this.cellEditor.getViewer().getCCombo();
KeyAdapter keyAdapter = new KeyAdapter()
{
  @Override
  public void keyPressed(final KeyEvent evt)
  {
  // KeyPreferenceUtils is used to get the eclipse workbench key preference values.
    int keyCode = KeyPreferenceUtils.getKeyValue();
    if ((evt.stateMask == SWT.CTRL) || (evt.stateMask == SWT.ALT) || (evt.stateMask == SWT.SHIFT) || (evt.stateMask == SWT.COMMAND))
    {
      String pressedKey = Action.convertAccelerator(evt.stateMask + evt.keyCode);
      int pressedKeyValue = Action.convertAccelerator(pressedKey);
      if (pressedKeyValue == keyCode)
      {
        comboBox.setListVisible(true);
      }
    }
    else if (evt.keyCode == keyCode)
    {
      comboBox.setListVisible(true);
    }
  }
};
comboBox.addKeyListener(keyAdapter);

Now my problem is i want detect 3 key presses. I.e, Ctrl+Shift+2 or some keys combination.

Answer 1

I don't know SWT that well but I'd assume evt.stateMask is an int used to represent a bit field and the SWT.XXX values represent masks for the corresponding bits. Thus you could try if (evt.stateMask & SWT.CTRL > 0 && evt.stateMask & SWT.SHIFT > 0).

To clarify evt.stateMask & SWT.CTRL > 0 would mean that if the bit defined by SWT.CTRL is set in stateMask you'll get a value greater than 0 otherwise you get 0. However, if other bits are set as well you'll not detect that with that approach.

If you only want to allow those bits to be set you could try if (evt.stateMask == (SWT.CTRL | SWT.SHIFT) ) (i.e. you combine the two masks ans then compare).

Example:

We'll use 8-bit values for simplicity and assume SWT.CTRL = 00000001 and SWT.SHIFT = 00000100.

With the first approach you'd get true for masks like 10000101, 00010101, 00000101 and false for masks like 00100100 etc.

With the second approach you'd only get true for stateMask = 00000101.