Fix case where percent = 0 causes error in display_progress_bar

[paul-1]

Occasionally the first draw of the progress bar is actually at 0% complete. This causes a problem in the math to calculate how full the progress bar is. The error is that x2 is not >= x1

[AndreaFavero71]

Hi Paul, your proposal is correct: Accoring to the PIL documentation, indeed X2 must be >= X1

The strange thing is that it has worked for so long the way it is. I just wanted to check what happens when x2<x1:

if __name__ == "__main__":
    """the main function can be used to test the display. """

    import time
    display.set_backlight(1)                                    # display backlight is set on
    print("barLength:", "\tpercent:", "\tfilledPixels:", "\tfilledPixels-(x+gap):")
    for i in range(-10,101):
        display.display_progress_bar(i, scrambling=False)
        if i in (-1,0,1,100):
            time.sleep(10)
        else:
            time.sleep(0.05)

The initial printout is:

barLength:  percent:    filledPixels:   filledPixels-(x+gap):
126      -10     6   -12
126      -9      7   -11
126      -8      8   -10
126      -7      9   -9
126      -6      10      -8
126      -5      12      -6
126      -4      13      -5
126      -3      14      -4
126      -2      15      -3
126      -1      16      -2
126      0   18      0
126      1   19      1
126      2   20      2
126      3   21      3

In my case, when x2<x1, the rectangles fills to the left of the (x1) origin yet not error. Could you kindly elaborate on the error you're experiencing?

[paul-1]

My guess is that its the newer version of the pillow library. I just installed mine last weekend. The exception was added in pillow version 9.5.0

Here is the pull request that changed to an exception https://github.com/python-pillow/Pillow/pull/6978

[AndreaFavero71]

You're right. By updating from the 8.12 I had to the latest 10.2.0 I got the error "ValueError: x1 must be greater than or equal to x0". Thank you for spotting the error and the fix.