To calculate the size of the small map, use this form
 
Max width of the small map  Max height of the small map
Min width of the small map  Min height of the small map
 
width of the map
height of the map
Width of the small map
Height of the small map

To launch zoommap use this kind of line (javascript):

open('zoommap/index.php? MAP=<MAP>& //filename of the map
  SMALLMAP=<SMALLMAP>& //filename of the smallmap
  MAPNAME=<MAPNAME>& //name of the map
  INFO=<INFO>& //information for printing
  TTF_SIZE=<TTF_SIZE>& //size of font for printing
  TITLECOLOR=<TITLECOLOR>& //color of the title for printing
  INFOCOLOR=<INFOCOLOR>', //color of info for printing
  'zoommap', //name of the window
  'width='+screen.width*0.7+',height='+screen.height*0.7+', //size of the window, here 70% of the screen
  scrollbars=no,resizable=1,toolbar=no,status=0,menubar=false') //attribute of the window

Test php install Launch zoommap Read user's manual Read developer's guide