text: import vcs
  import sys
  import argparse
  import vcs.testing.regression as regression
  import os
  
  p =argparse.ArgumentParser()
  
  p.add_argument("-H","--fitToHeight",default=True,action="store_false")
  p.add_argument("-u","--units",default="percent")
  p.add_argument("-x","--xoffset",default=0,type=float)
  p.add_argument("-y","--yoffset",default=0,type=float)
  p.add_argument("-z","--zoom",default=1.,type=float)
  p.add_argument("-s","--source",default="./somefile.png")
  
  args = p.parse_args(sys.argv[1:])
  print args
  bg=True
  x=vcs.init(bg=bg,geometry=(1200,800))
  x.open()
  png = os.path.join(sys.prefix,"share","uvcdat","sample_data","BlueMarble.ppm")
  x.put_png_on_canvas(png,args.zoom,args.xoffset,args.yoffset,args.units,args.fitToHeight)
  fnm = "test_vcs_put_png_on_canvas_%s_%s_%s_%s_%s" % (args.zoom,args.xoffset,args.yoffset,args.units,args.fitToHeight)
  x.png(fnm)
  ret = regression.check_result_image(fnm+'.png',args.source,20.)
  