from Myro import *

#Change all green pixels to white, and all other
# pixels to black.
def markGreen(myPic):
  for pix in getPixels(myPic):
     r = getRed(pix)
     g = getGreen(pix)
     b = getBlue(pix)
     if r < 70 and b < 70 and g > 100:
        setRed(pix,255)
        setGreen(pix,255)
        setBlue(pix,255)
     else:
       setRed(pix,0)
       setGreen(pix,0)
       setBlue(pix,0)


#Return the percentage of the picture that is marked (green)
#as a floating point number between 0.0 (0%) and 1.0 (100%)
#Only works well on images created by markGreen (above)
def pctMarked(pic):
   totalPixels = 0
   whitePixels = 0
   for pix in getPixels(pic):
      if getRed(pix) == 255:
          whitePixels = whitePixels + 1

      totalPixels = totalPixels + 1

   result = whitePixels / float( totalPixels)   #float conversion for python2
   return result


#Find where the wall is located in the image (left/right/center)
# Makes a number that represents the location of the center of
# the white pixels (wall). Assumes the input image will be black
# and white.
def findAvgX(pic):
   pixelCount  = 0
   totalXCount = 0
   for pix in getPixels(pic):
      if getRed(pix) == 255:
          x = getX(pix)
          totalXCount = totalXCount + x
          pixelCount = pixelCount + 1
   avgX = totalXCount / float( pixelCount)  #Float for python2
   return avgX

#Draws a vertical green line at a specified position.
def drawVLine(pic, position):
   pHeight = getHeight(pic)
   for y in range(pHeight):
      pix = getPixel(pic,position,y)
      setRed(pix,0)
      setGreen(pix,255)
      setBlue(pix,0)

#Test code:
p = makePicture("rca1.gif")
show(p, "Original")
p2 = copyPicture(p)
markGreen(p2)
result = pctMarked(p2)
print("{:.1f}% of the image is green".format(result*100) )
if result > 0.02:
  print("We found a green wall!")
  avgX = findAvgX(p2)
  print("Average X position is:", avgX)
  drawVLine(p2,int(avgX) )


show(p2, "result")