How can I make a Button more responsive?

Question

I have noticed that some Buttons don\'t seem as responsive as they could be. This applies equally to my app and to most other apps I\'ve tried.

When I press a Button

Answer 1

This seems to fix it:

public boolean onTouchEvent (MotionEvent event) {
   if (event.getAction() == MotionEvent.ACTION_DOWN) setPressed(true);
   return super.onTouchEvent(event);
}

Still not perfect, but better.

Answer 2

I have dug into the Android source code to see what was going on.

It turns out that the android.view.View class (from which Button derives) enters a "PREPRESSED" state before going into the PRESSED state:

android.view.View:

1529    /**
1530      * Indicates a prepressed state;
1531      * the short time between ACTION_DOWN and recognizing
1532      * a 'real' press. Prepressed is used to recognize quick taps
1533      * even when they are shorter than ViewConfiguration.getTapTimeout().
1534      * 
1535      * @hide
1536      */
1537     private static final int PREPRESSED             = 0x02000000;

android.view.ViewConfiguration.getTapTimeout() is 115 ms on my Nexus One, which is a lot longer than my estimation.

android.view.ViewConfiguration:

67     /**
68      * Defines the duration in milliseconds we will wait to see if a touch event 
69      * is a tap or a scroll. If the user does not move within this interval, it is
70      * considered to be a tap. 
71      */
72     private static final int TAP_TIMEOUT = 115;

Anyway, from examining View.onTouchEvent is doesn't look like there's a way to avoid this PREPRESSED state by any standard option. Which is a real shame.

The good news is that I have now verified that the way to avoid this lag is to subclass and override onTouchEvent.

Thanks for the discussion and answers.

Answer 3

So what basically happens in any Android application is that the GUI runs in the main thread. If you happen to run some other heavy stuff in the same thread, like communication, video, loops etc. these activities will definitely slow your GUI down. This has happened to my app in the past, then I moved all other processes to a separate thread each and the GUI became really real-time responsive.

Answer 4

Well... I usually extend Button class and override onTouchEvent method

public boolean onTouchEvent (MotionEvent event) 
{
   if (event.getAction() == MotionEvent.ACTION_DOWN) 
   {
      setPressed(true);
   }
   return super.onTouchEvent(event);
}