Capturing x,y Coordinates with Python PIL

Question

I want to display an image to the user with PIL and when the user clicks anywhere on this image, I want a def onmousedown(x,y) to be called. I will do some extra stuff in this function. How can I do this in PIL?

Thanks,

Answer 1

PIL won't do it alone -- PIL is an image manipulation library with no User Interfaces - it does have a showmethod, which does open an external program which displays the image, but does not communicate back with the Python process.

Therefore, in order to be able to get a user to interact with an image, one does have to build a GUI program using one of the consolidated toolkits for use with Python - the better known ones are Tkinter, GTK and Qt4. Tkinter is interesting because it comes pre-installed with Windows Python installs, and therefore is more easily available for users of that system. Windows users would have to separately download and install gtk or qt libraries to be able to use your program if you decide to use on of the other toolkits.

Here is a minimalist example of a Tkinter application with a clickable image:

import Tkinter
from PIL import Image, ImageTk
from sys import argv

window = Tkinter.Tk(className="bla")

image = Image.open(argv[1] if len(argv) >=2 else "bla2.png")
canvas = Tkinter.Canvas(window, width=image.size[0], height=image.size[1])
canvas.pack()
image_tk = ImageTk.PhotoImage(image)
canvas.create_image(image.size[0]//2, image.size[1]//2, image=image_tk)

def callback(event):
    print "clicked at: ", event.x, event.y

canvas.bind("<Button-1>", callback)
Tkinter.mainloop()

Answer 2

Here is another related post

How to display picture and get mouse click coordinate on it

On Ubuntu to install

sudo apt-get install python python-tk idle python-pmw python-imaging python-imaging-tk

Then it all works.

I added a resize to @jsbueno's solution and fixed one import issue.

import Tkinter
from PIL import ImageDraw, Image, ImageTk
import sys

window = Tkinter.Tk(className="bla")

image = Image.open(sys.argv[1] if len(sys.argv) >=2 else "bla2.png")
image = image.resize((1000, 800), Image.ANTIALIAS)
canvas = Tkinter.Canvas(window, width=image.size[0], height=image.size[1])
canvas.pack()
image_tk = ImageTk.PhotoImage(image)

canvas.create_image(image.size[0]//2, image.size[1]//2, image=image_tk)

def callback(event):
    print "clicked at: ", event.x, event.y

canvas.bind("<Button-1>", callback)
Tkinter.mainloop()