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Monday, September 26, 2016

Android: Blocking swipe-to-refresh on minimized AppBar

If you are designing an User-Interface that is using a CollapsingToolbarLayout and SwipeReshLayout, you may notice discomfort when flipping down the content, seen in CollapsingToolbarLayout that immediately trigger swipe-to-refresh.

 Here I'm sharing a code below.

 
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/**
 * Block SwipeRefreshLayout in collapsed and idle state.
 */
public class AppBarRefreshAdjustListener implements AppBarLayout.OnOffsetChangedListener {

    private static final long BLOCK_DELAY = 1000L;

    private final SwipeRefreshLayout mSwipeRefreshLayout;
    private int mVerticalOffset;
    private Handler mHandler = new Handler();

    public AppBarRefreshAdjustListener(SwipeRefreshLayout refreshLayout) {
        mSwipeRefreshLayout = refreshLayout;
        handleOffsetChanged(mVerticalOffset);
    }

    @Override
    public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
        handleOffsetChanged(verticalOffset);
    }

    private void handleOffsetChanged(int verticalOffset) {
        if (verticalOffset == 0) {
            mHandler.removeCallbacksAndMessages(null);
            mHandler.postDelayed(() -> {
                mSwipeRefreshLayout.setEnabled(mVerticalOffset == 0);
            }, BLOCK_DELAY);
        } else {
            mSwipeRefreshLayout.setEnabled(false);
        }
        mVerticalOffset = verticalOffset;
    }
}

This class solves the problem - blocking SwipeRefreshLayout on clotting time / AppBar deployment: 

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appBarLayout addOnOffsetChangedListener (new AppBarRefreshAdjustListener (swipeRefreshLayout) );

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