Python Flag Overlays

overlay.py

from PIL import Image, ImageDraw

# The RGBA opacity for flag stripes
# 0 is the lowest opacity, 255 highest (no opacity at all)
rgba_opacity = 155

overlays = {
    "EST": {
        "orientation": "horizontal",
        "colors": [
            (0, 114, 206, rgba_opacity),
            (0, 0, 0, rgba_opacity),
            (255, 255, 255, rgba_opacity),
        ]
    },
    "FRA": {
        "orientation": "vertical",
        "colors": [
            (0, 35, 149, rgba_opacity),
            (255, 255, 255, rgba_opacity),
            (237, 41, 57, rgba_opacity),
        ]
    },
    "ITA": {
        "orientation": "vertical",
        "colors": [
            (0, 146, 70, rgba_opacity),
            (255, 255, 255, rgba_opacity),
            (206, 43, 55, rgba_opacity)
        ]
    },
    "DEU": {
        "orientation": "horizontal",
        "colors": [
            (0, 0, 0, rgba_opacity),
            (221, 0, 0, rgba_opacity),
            (255, 206, 0, rgba_opacity)
        ]
    }
}

while True:
    # Get the flag overlay from input
    overlay = input("Which flag overlay do you want to apply? [" + ', '.join(list(overlays)) + "] ").upper()
    if overlay in overlays:
        break
    else:
        print("Invalid input! Please try again.")

# Open the source image in project directory
source_img = Image.open("base.jpg").convert("RGBA")
# Make a blank image for the rectangle, initialized to a transparent color.
tmp = Image.new("RGBA", source_img.size, (255, 255, 255, 0))
# Create a drawing context for it.
draw = ImageDraw.Draw(tmp)
# Extract width and height from tuple for later use
width, height = source_img.size

orientation = overlays[overlay]["orientation"]
stripes = len(overlays[overlay]["colors"])

# Draw the stripes on a temporary image.
# After that, merge the temporary image on the source image
counter = 0
if orientation == "horizontal":
    stripe = height / stripes
    for x in overlays[overlay]["colors"]:
        if counter == 0:
            draw.rectangle(((0, 0), (width, stripe)), x)
        else:
            draw.rectangle(((0, stripe * counter), (width, stripe * (counter + 1))), x)
        counter += 1
else:
    stripe = width / stripes
    for x in overlays[overlay]["colors"]:
        if counter == 0:
            draw.rectangle(((0, 0), (stripe, height)), x)
        else:
            draw.rectangle(((stripe * counter, 0), (stripe * (counter + 1), height)), x)
        counter += 1
# Merge the source image and temporary image
# We need to convert it to RGB to save it as JPG
out = Image.alpha_composite(source_img, tmp).convert("RGB")
out.save("overlay_"+overlay+".jpg")