utils/watermark_utils.py

import os.path as osp
from PIL import Image

def apply_watermark_to_pil_image(img_pil: Image.Image, watermark_path: str, opacity: float = 0.7) -> Image.Image:
    """
    Apply watermark to a PIL image
    
    Args:
        img_pil (Image.Image): Source PIL image
        watermark_path (str): Path to watermark image
        opacity (float): Watermark opacity (0.0 - 1.0)
    
    Returns:
        Image.Image: Watermarked PIL image
    """
    if not osp.exists(watermark_path):
        return img_pil
    
    try:
        watermark = Image.open(watermark_path)
    except Exception:
        return img_pil

    # Ensure images are in RGBA mode
    if img_pil.mode != 'RGBA':
        img_pil = img_pil.convert('RGBA')
    if watermark.mode != 'RGBA':
        watermark = watermark.convert('RGBA')

    # Fixed watermark size (adjust as needed)
    WATERMARK_FIXED_WIDTH = 418
    WATERMARK_FIXED_HEIGHT = 120
    
    # Resize watermark
    watermark = watermark.resize((WATERMARK_FIXED_WIDTH, WATERMARK_FIXED_HEIGHT), Image.LANCZOS)

    # Apply opacity
    if opacity < 1.0:
        alpha = watermark.split()[3]
        alpha = alpha.point(lambda p: p * opacity)
        watermark.putalpha(alpha)

    # Get image dimensions
    img_width, img_height = img_pil.size
    
    # Create transparent layer for watermarks
    wm_layer = Image.new('RGBA', img_pil.size, (0, 0, 0, 0))

    # Calculate watermark positions (bottom to top)
    initial_y = img_height - watermark.height - 10  # 10px from bottom
    x_position = 10  # 10px from left

    # Repeat watermark vertically
    current_y = initial_y
    while current_y > -watermark.height:
        if current_y < 0:
            # Crop watermark if it goes beyond top boundary
            crop_height = watermark.height + current_y
            if crop_height > 0:
                partial_wm = watermark.crop((0, -current_y, watermark.width, watermark.height))
                wm_layer.paste(partial_wm, (x_position, 0), partial_wm)
        else:
            wm_layer.paste(watermark, (x_position, current_y), watermark)
        
        current_y -= 8000  # Vertical spacing (adjust as needed)
    
    # Composite original image with watermark layer
    return Image.alpha_composite(img_pil, wm_layer)