Add tools/watermark.py

给配图加 CyC2018 浅水印：整张图斜向平铺淡色文字，右下角加与已有配图一致的标识。加过水印的图片会写入元数据标记，重复执行时跳过；--check 只检查不修改。

tools/watermark.py

@@ -0,0 +1,161 @@
+"""给配图加 CyC2018 浅水印。
+
+用法：
+    python3 tools/watermark.py notes/pics/a.png notes/pics/b.jpg
+    python3 tools/watermark.py --check notes/pics/*.png    # 只检查，不修改
+
+水印分两层：
+- 整张图斜向平铺一层很淡的 “CyC2018” 文字，不影响阅读；
+- 右下角加上与已有配图一致的浅灰色猫头图标和 “CyC2018”，右下角有内容时在底部补白边。
+角标大小按图片宽度自动缩放，也可以用 --scale 指定。
+
+加过水印的图片会在元数据中写入标记，再次执行时直接跳过，不会重复叠加。
+GIF 动图不处理。依赖 Pillow。
+"""
+import argparse
+import os
+import sys
+
+from PIL import Image, ImageDraw, ImageFont, PngImagePlugin
+
+TEXT = "CyC2018"
+MARK = "Watermark: CyC2018"
+GRAY = (128, 128, 128)
+ALPHA = 0.57          # 角标：白底上约为 #B7B7B7，与已有配图的水印深浅一致
+TILE_ALPHA = 0.07     # 平铺：白底上约为 #F6F6F6，只在留意时可见
+TILE_ANGLE = 30       # 平铺文字的倾斜角度
+SS = 4                # 超采样倍数，用于抗锯齿
+
+FONTS = [  # 等宽字体，与已有水印一致
+    "/System/Library/Fonts/Menlo.ttc",
+    "/usr/share/fonts/truetype/dejavu/DejaVuSansMono.ttf",
+    "C:/Windows/Fonts/consola.ttf",
+]
+
+
+def _font(size):
+    for path in FONTS:
+        if os.path.exists(path):
+            return ImageFont.truetype(path, size)
+    return ImageFont.load_default(size)
+
+
+def _mark(scale):
+    """生成右下角水印的 alpha 蒙版。"""
+    icon = round(24 * scale) * SS
+    font = _font(round(19 * scale) * SS)
+    left, top, right, bottom = font.getbbox(TEXT)
+    gap = round(8 * scale) * SS
+    w = icon + gap + right
+    h = max(icon, bottom - top)
+    mask = Image.new("L", (w, h), 0)
+    d = ImageDraw.Draw(mask)
+
+    # 猫头图标：按 100×100 网格绘制后缩放
+    def p(x, y):
+        return (x * icon / 100, (h - icon) / 2 + y * icon / 100)
+
+    d.polygon([p(10, 50), p(14, 4), p(46, 26)], fill=255)
+    d.polygon([p(90, 50), p(86, 4), p(54, 26)], fill=255)
+    d.rounded_rectangle([p(6, 22), p(94, 96)], radius=34 * icon / 100, fill=255)
+    d.rounded_rectangle([p(18, 54), p(82, 88)], radius=16 * icon / 100, fill=0)
+    d.ellipse([p(31, 61), p(41, 79)], fill=255)
+    d.ellipse([p(59, 61), p(69, 79)], fill=255)
+
+    d.text((icon + gap, (h - (bottom - top)) / 2 - top), TEXT, font=font, fill=255)
+    return mask.resize((w // SS, h // SS), Image.LANCZOS)
+
+
+def _tiles(size, scale):
+    """生成整张图斜向平铺的文字蒙版。"""
+    W, H = size
+    font = _font(round(15 * scale))
+    right = font.getbbox(TEXT)[2]
+    dx, dy = round(right * 2.6), round(85 * scale)
+    side = int((W ** 2 + H ** 2) ** 0.5) + 2 * dx
+    big = Image.new("L", (side, side), 0)
+    d = ImageDraw.Draw(big)
+    for row, y in enumerate(range(0, side, dy)):
+        for x in range(-dx + (dx // 2) * (row % 2), side, dx):
+            d.text((x, y), TEXT, font=font, fill=255)
+    big = big.rotate(TILE_ANGLE, resample=Image.BICUBIC)
+    l, t = (side - W) // 2, (side - H) // 2
+    return big.crop((l, t, l + W, t + H))
+
+
+def _blank(img, box):
+    """判断区域内是否基本为空白。"""
+    region = img.crop(box).convert("L")
+    dark = sum(1 for v in region.getdata() if v < 235)
+    return dark <= region.width * region.height * 0.002
+
+
+def add(img, scale=None):
+    """返回加了水印的新图片。scale 默认按宽度计算，1000px 宽的图为 1。"""
+    if scale is None:
+        scale = min(max(img.width / 1000, 0.6), 2.0)
+    img = img.convert("RGBA") if img.mode in ("P", "LA", "RGBA") else img.convert("RGB")
+    mask = _mark(scale)
+    mx, my = round(12 * scale), round(6 * scale)
+    W, H = img.size
+    box = (W - mask.width - 2 * mx, H - mask.height - 2 * my, W, H)
+    if box[0] < 0 or not _blank(img, box):
+        bg = (255, 255, 255, 255) if img.mode == "RGBA" else (255, 255, 255)
+        padded = Image.new(img.mode, (W, H + mask.height + 2 * my), bg)
+        padded.paste(img, (0, 0))
+        img, H = padded, padded.height
+    layer = Image.new(img.mode, img.size, GRAY + ((255,) if img.mode == "RGBA" else ()))
+    img.paste(layer, (0, 0), _tiles(img.size, scale).point(lambda v: round(v * TILE_ALPHA)))
+    corner = Image.new("L", img.size, 0)
+    corner.paste(mask.point(lambda v: round(v * ALPHA)), (W - mask.width - mx, H - mask.height - my))
+    img.paste(layer, (0, 0), corner)
+    return img
+
+
+def marked(img):
+    """图片是否已经加过水印。"""
+    value = img.info.get("Watermark") or img.info.get("comment") or b""
+    if isinstance(value, bytes):
+        value = value.decode("utf-8", "ignore")
+    return "CyC2018" in value
+
+
+def save(img, path):
+    """保存图片并写入水印标记。"""
+    if path.lower().endswith(".png"):
+        info = PngImagePlugin.PngInfo()
+        info.add_text("Watermark", "CyC2018")
+        img.save(path, pnginfo=info, optimize=True)
+    else:
+        img.convert("RGB").save(path, quality=92, comment=MARK.encode())
+
+
+def main():
+    ap = argparse.ArgumentParser(description="给配图加 CyC2018 浅水印")
+    ap.add_argument("images", nargs="+")
+    ap.add_argument("--scale", type=float, help="角标缩放，默认按图片宽度计算")
+    ap.add_argument("--check", action="store_true", help="只检查是否已加水印")
+    ap.add_argument("--mark-only", action="store_true", help="图片已有水印，只写入标记")
+    args = ap.parse_args()
+    missing = 0
+    for path in args.images:
+        if not path.lower().endswith((".png", ".jpg", ".jpeg")):
+            print("skip (not png/jpg)", path)
+            continue
+        img = Image.open(path)
+        if marked(img):
+            print("ok", path)
+        elif args.check:
+            print("missing watermark", path)
+            missing += 1
+        elif args.mark_only:
+            save(img, path)
+            print("marked", path)
+        else:
+            save(add(img, args.scale), path)
+            print("watermarked", path)
+    sys.exit(1 if missing else 0)
+
+
+if __name__ == "__main__":
+    main()