如何在 SWT 中监听粘贴键盘快捷键

Question

I want to globally listen for CTRL + v in SWT. I can successfully listen for CTRL + c but paste seems to be handled differently in SWT. The following Listener shows how it works for copy and how it does not work for paste:

display.addFilter(SWT.KeyDown, new Listener() {

        private final int CTRL = SWT.MOD1;
        private boolean checkNextEventForPaste = false;

        @Override
        public void handleEvent(Event event) {
            if(event.stateMask == CTRL && event.keyCode == 'c'){
                System.out.println("copy: this works!");
            }
            else if(event.stateMask == CTRL && (event.keyCode == 'v'
                    || event.keyCode == 'V'
                    || event.keyCode == 0x16
                    || event.keyCode == 118)){
                System.out.println("paste: does not work!");
            }

            else if (event.keyCode == CTRL){
                //control for paste is fired first
                checkNextEventForPaste  = true;
            }
            else if(checkNextEventForPaste){
                if(event.keyCode == 65536){
                    System.out.println("custom solution: seems to not only apply for paste");
                }
                checkNextEventForPaste = false;
            }
        }

    });

I debugged the paste case and created a custom solution. The paste keyboard short cut creates the following event sequence:

• first event with stateMask = 0 and keyCode = CTRL
• second event with stateMask = 0 and keyCode = 65536

The problem is that the custom paste solution seems to apply for other shortcuts too. For example the copy shortcut creates the following event sequence:

• first event with stateMask = 0 and keyCode = CTRL
• second event with stateMask = CTRL and keyCode = 'c'
• third event with stateMask = 0 and keyCode = 65536

Why does SWT handle the paste shortcut in a different way? Is it possible that the paste shortcut is already consumed by an other control? Or does anybody know how I can identify the paste shortcut? A VerifyListener is not applicable in my use case. I have implemented a more or less complex UI with custom selection, as you can see here .

Answer 1

The code below works just fine for both Ctrl + c and Ctrl + v

public static void main(String[] args)
{
    final Display d = new Display();
    Shell s = new Shell(d);

    d.addFilter(SWT.KeyDown, e ->
    {
        if (((e.stateMask & SWT.CTRL) == SWT.CTRL) && (e.keyCode == 'c'))
        {
            System.out.println("copy");
        }
        else if (((e.stateMask & SWT.CTRL) == SWT.CTRL) && (e.keyCode == 'v'))
        {
            System.out.println("paste");
        }
    });

    s.pack();
    s.open();

    while (!s.isDisposed())
    {
        if (!d.readAndDispatch())
            d.sleep();
    }
    d.dispose();
}