#create the mirror image of a picture
#
#A little geometry:  The reflection of the
#pixel at position X,Y is the pixel at positon
#width+1-X,Y
#
#This corrects the error in the previous version by
#setting up a second canvas on which to do the painting
def mirror2():
  file=pickAFile()
  sourcepic=makePicture(file)
  destpic=makePicture(file)
#this was just to get a picture the same size
  width=getWidth(sourcepic)
  for px in getPixels(sourcepic):
    x=getX(px)
    y=getY(px)
    px2=getPixel(destpic,width+1-x,y)
    setColor(px2,getColor(px))
    setColor(px,getColor(px2))
  show(destpic)