How to differentiate between a fling and a touch?

Question

I have a ListView inside of a ViewFlipper which I am flipping when the user swipes across the screen. Clicking on a ListView will open the browser. Sometimes when I am swiping,

Answer 1

The way this is normally done is through the parent view's onInterceptTouchEvent method. onInterceptTouchEvent has a chance to see any touch event before a view's children do. If onInterceptTouchEvent returns true the child view that was previously handling touch events receives an ACTION_CANCEL and the events from that point forward are sent to the parent's onTouchEvent method for the usual handling. It can also return false and simply spy on events as they travel down the view hierarchy to their usual targets.

You want to do essentially this in onInterceptTouchEvent on the parent view where you're detecting the flings:

• On ACTION_DOWN, record the location of the touch. Return false.
• On ACTION_MOVE, check the delta between initial touch down position and current position. If it's past a threshold value, (the framework uses ViewConfiguration#getScaledTouchSlop() or other appropriate values from ViewConfiguration for things like this,) return true.
• Detect and handle the fling as usual based on onTouchEvent.

Once you intercept, the ListView will cancel its touch handling and you won't get unwanted tap events on your list items. ListView is also set up to disallow its parent from intercepting events once the user has started vertically scrolling the list, which means you won't get mistaken horizontal flings if the user sloppily flings the list vertically.

This is how things like the stock Android Launcher or News and Weather do side to side paging of scrolling/tappable content.