You can implement it as follows:
- you can set a variable based on which highlight all search query in a page for example (boolean findAll)
- in vDraw check your variable:
if( m_finder.find_get_page() == cur )
    if(findAll)
         m_finder.find_draw_all(bcan, vpage, left, top);
    else
         m_finder.find_draw(bcan, vpage, left, top);- then in PDFVFinder add find_draw_all that look like: (note not tested)
protected void find_draw_all(Canvas canvas, PDFVPage page, int scrollx, int scrolly) {
	m_page_find_index = 0;
	while(m_page_find_index < m_page_find_cnt) { 
		find_draw(canvas, page, scrollx, scrolly);
		m_page_find_index++;
	}
}