Create a png image using classes

Question

What i'm trying to do is to create a png image using specified parameters, like:

img = Image(200, 100, Color(0, 0, 255))
h_line(img, 20, Color(255, 0, 0))
c = img.get_pixel(20, 20)
c.b = 200
img2 = img.copy()
h_line(img, 40, Color(255, 0, 0))
save('file01_01_out.png', img)

This is what I wrote so far:

    import png

class Color(object):
    def __init__(self, r, g, b):
        self.r = r
        self.g = g
        self.b = b

    def copy(self):
        return Color(self.r, self.g, self.b)

class Image(object):
    #'''Class must have height and width attributes'''
    def __init__(self, width, height, c):
        self.width = width
        self.height = height
        self.c = Color
        #'''Initializes the image with width, height and every pixel with copies of c
       # c being an object of Color type'''
 #    

    def set_pixel(self, x, y, c):
        self.img.put("{" + c +"}", (x, y))
       # '''Sets the color in position (x, y) with a copy of object
        #    c of type Color. If the position (x, y) is beyond the
        #    object, then it won't do anything'''

    def get_pixel(self, x, y):
        value = self.img.get(x,y) 
        if type(value) ==  type(0):
            return [value, value, value]
        else:
            return None 
#        '''Returns a copy of the color (Color type) in position
#           (x, y). If (x, y) is beyond the picture, it will return
#           None'''

    def copy(self):
        return Image(self.width, self.height, self.c)


def h_line(img, y, c):
    for x in range(img.width):
        img.set_pixel(x, y, c)

def save(filename, img):
    png_img = []
    for i in range(img.height):
        png_row = []
        for j in range(img.width):
            c = img.get_pixel(j, i)
            png_row.extend([c.r, c.g, c.b])
        png_img.append(png_row)
    with open(filename, 'wb') as f:
        png.Writer(img.width, img.height).write(f, png_img)

The problem is that the program won't crash but it won't save anything! I tried with different examples, yet the result is always the same. What am I doing wrong?

I'll be surprised if anyone can work with this (it's not self-contained or runnable for anyone else) - a lot of code appears to be missing or just not properly indented - for instance: self.img is what exactly? (And if I understand what you're doing correctly, it's just a couple of lines using PIL anyway...) — Jon Clements
– Jon Clements, Commented Dec 23, 2012 at 19:36

Jon Clements · Accepted Answer · 2012-12-23 19:54:58Z

1

Update - just noticed the Py3 tag - so answer may not be valid - but potentially of some use

As an example - using PIL - you can create a 200x200 image with a certain RGB colour, and then just save it with a .png extension...

>>> from PIL import Image
>>> img = Image.new('RGB', (200, 200), (127, 127, 127))
>>> img.save('/path/to/some/file.png')

Gives you:

Example image

answered Dec 23, 2012 at 19:54

Jon Clements

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1 Comment

test123 Over a year ago

Thank you, but I really need to use the PNG library unfortunately :(

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