map_viewso that I could size a raster_image on the map. I had always thought that
!window_system!.screen_resolution()would do that for me. It seemed to work as long as I put in some additional empirical fudge factor. I discovered later that if I am working with
map_view, I can use
map_view.pixel_sizeto calculate DPI.
map_view.pixel_sizereturns the size of a pixel in millimetres so to convert that to DPI...
## if!dpi : integer
## returns _self's DPI
_return (1/_self.pixel_size) * 25.4