RecyclerView smoothScrollToPosition on small distance is too fast

Question

In our chat app we use RecyclerView that can have messages with different heights. I want to animate message add with smoothScroll. My problem is: when I use recyclerView.smoothScrollToPosition(position) on messages with small height, it scrolls too fast.

I also tried this solution changing smoothScoll speed, its good for small messages, but when message is big its scroll speed making message appear too slow.

My perfect speed achieves with recyclerView.smoothScrollBy(x, y), but here I have problem getting inserted message height, since messages can have any height.

extend `LinearSmoothScroller` and override `calculateSpeedPerPixel` — pskink, Feb 10 '17 at 10:38
I already tried it. The speed on small items is good, but when I try big item, I got slow scroll speed. — Rafael, Feb 10 '17 at 10:41
I tried again that solution extending LinearSmoothScroller, and speed `MILLISECONDS_PER_INCH = 125f;` was OK for me. Thank you @pskink. — Rafael, Feb 10 '17 at 11:07

score 1 · Answer 1 · answered Aug 18 '21 at 22:17

Override calculateTimeForScrolling method of LinearSmoothScroller that calculate time for all distances:

public class SpeedyLinearLayoutManager extends LinearLayoutManager {

private int smoothScrollDuration;

public SpeedyLinearLayoutManager(Context context, int smoothScrollDuration) {
    super(context);
    this.smoothScrollDuration = smoothScrollDuration;
}

public SpeedyLinearLayoutManager(Context context, int orientation, boolean reverseLayout, int smoothScrollDuration) {
    super(context, orientation, reverseLayout);
    this.smoothScrollDuration = smoothScrollDuration;
}

public SpeedyLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes, int smoothScrollDuration) {
    super(context, attrs, defStyleAttr, defStyleRes);
    this.smoothScrollDuration = smoothScrollDuration;
}

@Override
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) {

    final LinearSmoothScroller linearSmoothScroller = new LinearSmoothScroller(recyclerView.getContext()) {

        @Override
        protected int calculateTimeForScrolling(int dx) {
            return smoothScrollDuration;
        }
    };

    linearSmoothScroller.setTargetPosition(position);
    startSmoothScroll(linearSmoothScroller);
}

public int getSmoothScrollDuration() {
    return smoothScrollDuration;
}

public void setSmoothScrollDuration(int smoothScrollDuration) {
    this.smoothScrollDuration = smoothScrollDuration;
}
}

And use it for recyclerview:

    LinearLayoutManager layoutManager = new SpeedyLinearLayoutManager(context, 100);
    mRecyclerView.setLayoutManager(layoutManager);

RecyclerView smoothScrollToPosition on small distance is too fast

1 Answers1