# -*- coding: utf-8 -*-
from PIL import Image, ImageDraw

src = r"D:\workspace\code\app\.workbuddy\hongbao.webp"
img = Image.open(src).convert("RGBA")
w, h = img.size
tile = 16

# Panel 1: checkerboard background (shows transparency)
def make_checker(width, height, t):
    cb = Image.new("RGB", (width, height), (255, 255, 255))
    d = ImageDraw.Draw(cb)
    for y in range(0, height, t):
        for x in range(0, width, t):
            if (x // t + y // t) % 2 == 0:
                d.rectangle([x, y, x + t - 1, y + t - 1], fill=(204, 204, 204))
    return cb

checker = make_checker(w, h, tile).convert("RGBA")
panel1 = Image.alpha_composite(checker, img).convert("RGB")

# Panel 2: white background
white_bg = Image.new("RGBA", (w, h), (255, 255, 255, 255))
panel2 = Image.alpha_composite(white_bg, img).convert("RGB")

# Panel 3: alpha channel as grayscale (white = opaque, black = transparent)
alpha = img.split()[3]
panel3 = Image.merge("RGB", (alpha, alpha, alpha))

# Combine with labels
gap = 10
label_h = 28
total_w = w * 3 + gap * 2
total_h = h + label_h
canvas = Image.new("RGB", (total_w, total_h), (245, 245, 245))
canvas.paste(panel1, (0, label_h))
canvas.paste(panel2, (w + gap, label_h))
canvas.paste(panel3, (w * 2 + gap * 2, label_h))

d = ImageDraw.Draw(canvas)
d.text((4, 6), "Transparent bg (checker)", fill=(0, 0, 0))
d.text((w + gap + 4, 6), "White bg", fill=(0, 0, 0))
d.text((w * 2 + gap * 2 + 4, 6), "Alpha channel", fill=(0, 0, 0))

out = r"D:\workspace\code\app\.workbuddy\hongbao_bg_compare.png"
canvas.save(out)
print("Saved:", out)