Transparency in Tkinter PhotoImage

Question

In my simple game I'm creating I currently have placeholder rectangle objects as graphics. I'm trying to replace them with sprites, but as I understand it Tkinter doesn't have support for PNGs or alpha transparency. I am using Python 3.3, which doesn't work with PIL (and since it is a school project, I am solely trying to use Tkinter as the only external library). Is there a way to use the alpha channel with the supported file formats so that I can have multiple layers of tiles? I just want to filter out the white pixels.

Answer 1

I was able to use an image with transparency. I understand your wish to avoid use of PIL, but the following code works and demonstrates that Tkinter will support formats with transparency.

from Tkinter import Tk, Canvas
import PIL
root = Tk() 
tkimg = PIL.ImageTk.PhotoImage('cat1-a.gif')
canvas = Canvas(root, height=600, width=600)
canvas.grid()
def stamp(event):
    canvas.create_image(event.x, event.y, image=tkimg)
canvas.bind('<ButtonPress-1>', stamp)
root.mainloop()

Answer 2

To make the white pixels transparent (I am assuming that white means #ffffff) you could use this function below or something like it. This does not require PIL. It has worked for me for pngs, but also will work for gif.

• First, make a new blank image the same size as your image.
• Second, copy pixel by pixel to the new image (unless the pixel is white).
• Set your original image to the new image.

Here is an example of the function being used:

from tkinter import *


def makeTransparent(img, colorToMakeTransparentInHexFormat):
    newPhotoImage = PhotoImage(width=img.width(), height=img.height())
    for x in range(img.width()):
        for y in range(img.height()):
            rgb = '#%02x%02x%02x' % img.get(x, y)
            if rgb != colorToMakeTransparentInHexFormat:
                newPhotoImage.put(rgb, (x, y))
    return newPhotoImage


root = Tk()
mycanvas = Canvas(root, width=200, height=200,bg="orange")
mycanvas.pack()

myphotoImage = PhotoImage(file="whitecar.gif")
#set your image to the image returned by the function
myphotoImage = makeTransparent(myphotoImage, "#ffffff")
canvasImage = mycanvas.create_image(100, 100, image=myphotoImage, anchor=CENTER)

root.mainloop()

Here is an example of a white car with a white background:

Here is an example of that car on the canvas using the example program:

So I hope I have answered your question.

• I did not use PIL. nothing but the tkinter module.
• I only used gif, not png as you asked.
• Wherever white is, will now be transparent.

---

Note:

For whatever reason, processing transparency multiple times with the above function can result in viewing errors in tkinter. Below is a way to remove multiple colors by using a color switching function: Here is a car:

Here is another function to switch colors, which can be implemented before making a color transparent.

def switchColors(img, currentColor,futureColor):
    newPhotoImage = PhotoImage(width=img.width(), height=img.height())
    for x in range(img.width()):
        for y in range(img.height()):
            rgb = '#%02x%02x%02x' % img.get(x, y)
            if rgb == currentColor:
                newPhotoImage.put(futureColor, (x, y))
            else:
                newPhotoImage.put(rgb, (x, y))
    return newPhotoImage

Here it is in use

root = Tk()
mycanvas = Canvas(root, width=200, height=200,bg="orange")
mycanvas.pack()

myphotoImage = PhotoImage(file="car.png")

myphotoImage = switchColors(myphotoImage,"#db0000","#ffffff") #switch red to white
myphotoImage = switchColors(myphotoImage,"#d9d9d9","#ffffff") #switch greybackground to white
myphotoImage = switchColors(myphotoImage,"#6d6d6d","#ffffff") #switch windshield grey to white
myphotoImage = makeTransparent(myphotoImage,"#ffffff") #make white transparent

canvasImage = mycanvas.create_image(100, 100, image=myphotoImage, anchor=CENTER)

root.mainloop()

And here is the result of that process:

Here is a reference to a similar problem: How to rotate an image on a canvas without using PIL?

Answer 3

There is a way to use PIL with Python 3 using non-official versions of PIL Go to http://www.lfd.uci.edu/~gohlke/pythonlibs/ to download it.