Question

I am creating an application for video recording and I overlayed the video preview with labels txtStatus and txtTime.

The camera button starts/stops the timer which periodically calls the UpdateGUI method. Running the debug I can see the timer is working – it calls updateGUI method every second but the method doesn’t update the controls.

I would really appreciate if I could get any hint on how to fix this issue.

Here is the code:

This is the method which activates the timer:

private void startTimer()
{
    updateTimer = new Timer("TimerUpdate");
    updateTimer.scheduleAtFixedRate(new TimerTask(){
        public void run(){
            settings.IncreaseRecordingTime();
            updateGUI();

        }
    }, 0, 1000);
}

This is the updateGUI method:

private void updateGUI()
{
    setStatusLabel();
    String strTime = settings.GetTimerString(); //strTime changes every second (it works as expected)
    txtTimer.setText(strTime);//the text doesn't change!
}

And this is the method which is called when the button is pressed:

private boolean onCaptureButton()
{
    settings.CaptureAction();
    videoPreview.setFrameCallback(settings);
    updateGUI();//here the function updateGUI() works as expected - it changes the txtStatus text from "Preview" to "Recording"
    setTimer();
    return false;
}

I added some comments as well (don’t know why updateGUI() works when it is called at onCaptureButton() method and doesn’t work when called inside the timer method).

Answer 1

After updating each control call control.Refresh() or form.Refresh() – this forces the controls to be redrawn immediately.

In your case:

txtTimer.setText(strTime); // the text doesn't change!
txtTimer.Refresh();