GT.FixedButton

This extends the Ext.Button in Sencha Touch 2.0 for a different, more iOS like user experience. As the name suggests this works well for buttons that are fixed and not in a scrollable container. It might also work with buttons in a scrollable container but haven't tested yet.

Code and Example

The code is here: https://github.com/roycyang/sencha-touch-extensions An example is here: http://roycyang.github.com/sencha-touch-extensions/example

The Problem

Currently, Ext.Button has the following rules:

1. The button fires on the tap event. This is not optimal because the user needs to tap the button and release it exactly on the same pixel, or else the tap event doesn't fire. There is a thread about using moveThrottle (http://www.sencha.com/forum/showthread.php?188573-buttons-often-don-t-fire-a-tap-event-when-pressed&highlight=movethrottle) to give the tap event a tolerance:

	Ext.application({
	    eventPublishers: {
	        touchGesture: {
	            moveThrottle: 3
	        }
	    },
	    // ...
	});

But this code messes with the other touch events, making the carousel and all scrolling look choppy. Even if that choppiness was acceptable, a 3px or 5px tolerance still isn't good enough. Some users are "sloppy" tappers.

2. When you touch a button, the press state is added. Only when you let go (touchend), does the press state disappear. Even if you touch the button and drag your finger off, the press state remains. There is a fundamental flaw in the logic in that when the user sees the "press state" activated, they would expect the button to be "tapped" when they let go.

The Alternative

This attempts to solve the issues by doing the following:

1. The tap zone is now larger than the button itself. This is done using a tapmask and is inspired by SunboX and Lim Chee Aun's post: http://cheeaun.com/blog/2012/03/how-i-built-hacker-news-mobile-web-app#the-feel
2. Upon press, the tap zone is doubled.
3. The tap event is tied to touchstart and touchend. If you touch the button and then release and are still on tap zone, it will fire the tap event. The user can now be as "sloppy" as they want and there is a now a buffer zone around the button.
4. The press state is also tied to touchmove. If you activate the button press and then move your finger off the button, the press state disappears and the tap event won't fire.

Getting Started

To use this, add the following to your app.js:

Ext.Loader.setPath({
    'GT': 'GT'
});

From there, you will have access to the fixed button by using:

requires: ['GT.FixedButton']

//...
xtype: 'fixedbutton'
// these are default, only add if you are changing
tapMask: null, // change to true to see the zone, good for debugging
tapOverflowTop: 10, // in pixels
tapOverflowBottom: 10, // in pixels
tapOverflowLeft: 10, // in pixels
tapOverflowRight: 10 // in pixels