The default behavior of the vertical mode is to fit according to screen width.

If you want to make it fit to screen height instead, create a custom class that extends PDFLayoutVert as below (make sure to put it under package com.radaee.view, to be able to use all the protected properties).

public class VerticalFitHeight extends PDFLayoutVert {

    public VerticalFitHeight(Context context) {
        super(context);
    }

    @Override
    public void vLayout() {
        if(m_w <= 0 || m_h <= 0 || m_doc == null || m_pages == null) return;
        int cnt = m_doc.GetPageCount();
        int cur;
        m_scale_min = ((float)(m_h - m_page_gap)) / m_page_maxh;
        m_scale_max = m_scale_min * m_zoom_level;
        if(m_scale < m_scale_min) m_scale = m_scale_min;
        if(m_scale > m_scale_max) m_scale = m_scale_max;
        boolean clip = m_scale / m_scale_min > m_zoom_level_clip;
        m_tw = (int)(m_page_maxw * m_scale);
        if( m_tw < m_w ) m_tw = m_w;
        m_th = 0;
        int y = m_page_gap>>1;
        for(cur = 0;cur < cnt;cur++)
        {
            int w = (int)(m_doc.GetPageWidth(cur) * m_scale), cw = 0;
            int h = (int)(m_doc.GetPageHeight(cur) * m_scale);
            if (w + m_page_gap < m_w) cw = m_w;
            else cw = (int) (w + m_page_gap * m_scale);
            int x = Math.abs(cw - w) / 2;
            m_pages[cur].vLayout(x, y, m_scale, clip);
            y += h + m_page_gap;
        }
        m_th = y - (m_page_gap>>1);
    }
}

 Note, you need to modify PDFLayoutView.PDFSetView to use your custom class instead of PDFLayoutVert