import math
from PIL import Image

#from http://rosettacode.org/wiki/Map_range#Python
def maprange( a, b, s):
    (a1, a2), (b1, b2) = a, b
    r =  b1 + ((s - a1) * (b2 - b1) / float((a2 - a1)))
    return r

#from http://www.roguebasin.com/index.php?title=Bresenham%27s_Line_Algorithm#Python
def get_line(x1, y1, x2, y2):
    points = []
    issteep = abs(y2-y1) > abs(x2-x1)
    if issteep:
        x1, y1 = y1, x1
        x2, y2 = y2, x2
    rev = False
    if x1 > x2:
        x1, x2 = x2, x1
        y1, y2 = y2, y1
        rev = True
    deltax = x2 - x1
    deltay = abs(y2-y1)
    error = int(deltax / 2)
    y = y1
    ystep = None
    if y1 < y2:
        ystep = 1
    else:
        ystep = -1
    for x in range(x1, x2 + 1):
        if issteep:
            points.append((y, x))
        else:
            points.append((x, y))
        error -= deltay
        if error < 0:
            y += ystep
            error += deltax
    # Reverse the list if the coordinates were reversed
    if rev:
        points.reverse()
    return points

def polar(r,angle):
    x=r*math.cos(angle)
    y=r*math.sin(angle)
    return (x,y)


def readValue(image,value,debug=False):
    angleStep = math.pi/5
    target = polar(175,angleStep*value)
    target = (int(target[0]+320),int(target[1]+200))
    if debug: print target

    x = get_line(320,200,*target)
    if debug: print len(x)

    pxList = []
    for p in x:
        pxList.append(image.getpixel(p)[0])
    if debug: print pxList

    val = pxList.index(min(pxList))
    if debug: print val
    if debug: print x[val]


    blackList = [i for i,j in enumerate(pxList) if j<10]
    if debug: print blackList
    val = blackList[-1]

    if debug: print x[val]
    mappedVal = maprange((0,len(x)),(0,10),val)
    mappedVal = round(mappedVal,1)
    if debug: print 'val: {0}, mappedVal: {1}'.format(val, mappedVal)

    return mappedVal


im = Image.open("img01.jpg")

for i in range(10):
    print readValue(im,i)
print

#print readValue(im,0,True)