Android: How to detect when a scroll has ended

Question

I am using the onScroll method of GestureDetector.SimpleOnGestureListener to scroll a large bitmap on a canvas. When the scroll has ended I want to redraw the bitmap in case

Answer 1

I was looking into this same issue. I saw Akos Cz answer to your question. I created something similar, but with my version I noticed that it only worked for a regular scroll - meaning one that doesn't generate a fling. But if a fling did get generated - regardless if I processed a fling or not, then it did NOT detect the "ACTION_UP" in "onTouchEvent". Now maybe this was just something with my implementation, but if it was I couldn't figure out why.

After further investigation, I noticed that during a fling, the "ACTION_UP" was passed into "onFling" in "e2" every time. So I figured that must be why it wasn't being handled in "onTouchEvent" in those instances.

To make it work for me I only had to call a method to handle the "ACTION_UP" in "onFling" and then it worked for both types of scrolling. Below are the exact steps I took to implement in my app:

-initialized a "gestureScrolling" boolean to "false" in a constructor.

-I set it to "true" in "onScroll"

-created a method to handle the "ACTION_UP" event. Inside that event, I reset "gestureSCrolling" to false and then did the rest of the processing I needed to do.

-in "onTouchEvent", if an "ACTION_UP" was detected and "gestureScrolling" = true, then I called my method to handle "ACTION_UP"

-And the part that I did that was different was: I also called my method to handle "ACTION_UP" inside of "onFling".