android - RecyclerView fast scroll thumb height too small for large data set

Question

I am using the default RecyclerView fast scroll and I followed this guide to support it.

Now, the problem is that the thumb resizes its height as per the size of the data set. For large items like 100 and above, the thumb becomes very small and almost becomes difficult to respond to dragging.

Please is there any way I can set minimum height for the fast scroll thumb.

Answer 1

I solved this problem by copying the FastScroller class from android.support.v7.widget.FastScroller

Then I removed the fast scroll enabled from the xml and applied fastscroller using the below code:

StateListDrawable verticalThumbDrawable = (StateListDrawable) getResources().getDrawable(R.drawable.fastscroll_sunnah);
Drawable verticalTrackDrawable = getResources().getDrawable(R.drawable.fastscroll_line_drawable);
StateListDrawable horizontalThumbDrawable = (StateListDrawable)getResources().getDrawable(R.drawable.fastscroll_sunnah);
Drawable horizontalTrackDrawable = getResources().getDrawable(R.drawable.fastscroll_line_drawable);

Resources resources = getContext().getResources();
new FastScroller(recyclerView, verticalThumbDrawable, verticalTrackDrawable,
                horizontalThumbDrawable, horizontalTrackDrawable,
                resources.getDimensionPixelSize(R.dimen.fastscroll_default_thickness),
                resources.getDimensionPixelSize(R.dimen.fastscroll_minimum_range),
                resources.getDimensionPixelOffset(R.dimen.fastscroll_margin));

Inside the FastScroller Class I extended the defaultWidth:

FastScroller(RecyclerView recyclerView, StateListDrawable verticalThumbDrawable,
        Drawable verticalTrackDrawable, StateListDrawable horizontalThumbDrawable,
        Drawable horizontalTrackDrawable, int defaultWidth, int scrollbarMinimumRange,
        int margin) {
    ...
    this.defaultWidth = defaultWidth;
    ...

Then I updated the code in this method:

void updateScrollPosition(int offsetX, int offsetY) {
...
mVerticalThumbHeight = Math.max(defaultWidth * 4, Math.min(verticalVisibleLength,
                (verticalVisibleLength * verticalVisibleLength) / verticalContentLength));
...
...
mHorizontalThumbWidth = Math.max(defaultWidth * 4, Math.min(horizontalVisibleLength,
                (horizontalVisibleLength * horizontalVisibleLength) / horizontalContentLength));
...    
}

This ensures that the minimum thumb height/width is 4 times the default width.