💧 PDF 加水印Add Watermark

使用说明与常见问题How-to & FAQ

「PDF 加水印」是什么？What is the Add Watermark tool?

给 PDF 每页加文字水印（居中斜放）。本地处理。可设置「打开密码」、「水印文字」、「字号」、「不透明度 %」。Stamp a diagonal text watermark on every PDF page. Processed locally. Settings: Password, Watermark text, Font size, Opacity %.

如何使用「PDF 加水印」？How do I use the Add Watermark tool?

在「PDF 加水印」中，选择或拖入文件，按需设置「水印文字」、「字号」、「不透明度 %」等选项，然后点击「加水印」按钮即可。加密的 PDF 会提示输入密码（出现「打开密码」栏和「打开」按钮），输入密码并点「打开」后再继续。In the Add Watermark: Choose or drop your files, set "Watermark text", "Font size", "Opacity %", then click "Add watermark". For an encrypted PDF, the page asks for its password (a Password field and an Open button appear) — enter it, click Open, then continue.

PDF 会上传到服务器吗？Is my PDF uploaded to a server?

不会。水印由 pdf-lib 在浏览器本地绘制到每一页上，加了密码的 PDF 也在本地解锁，文件不会发送到任何服务器。No. pdf-lib draws the watermark onto each page locally in your browser, and password-protected PDFs are also unlocked locally, so nothing is sent to a server.

水印可以用中文吗？Can the watermark text be Chinese?

可以。只含英文字母、数字和常见符号时使用 PDF 标准字体 Helvetica Bold；文字里有中文、日文、韩文等字符时，会自动嵌入思源黑体（Noto Sans SC）中用到的字形，文件会稍大一些。字体里没有的字符（例如部分表情符号）会在处理前提示，不会变成问号。Yes. Text with only Latin letters, digits and common symbols uses the standard PDF font Helvetica Bold; when the text has Chinese, Japanese or Korean characters, the glyphs it uses from Noto Sans SC are embedded automatically, so the file grows a little. Characters the font lacks (such as some emoji) are reported before processing instead of turning into question marks.

改了设置需要重新点按钮吗？Do I need to click again after changing a setting?

不用。生成过一次之后，修改水印文字、字号或不透明度会自动重新生成（约半秒后）；如果刚改完就点下载，会先按新设置生成再下载。设置无效时，旧的下载链接会被移除，并显示错误。No. After the first run, editing the text, font size or opacity regenerates the file automatically (after about half a second); if you click Download straight after an edit, the file is rebuilt with the new settings first. An invalid setting removes the old download link and shows the error.

有哪些选项可以调整？What options can I adjust?

「PDF 加水印」的设置：「打开密码」可留空；「水印文字」默认 CONFIDENTIAL；「字号」默认 48；「不透明度 %」默认 25；可选文件：PDF。每次生成结果都按当前设置处理。Settings in the Add Watermark — "Password" optional; "Watermark text" default CONFIDENTIAL; "Font size" default 48; "Opacity %" default 25; files: PDF. The result always uses the current settings.

「PDF 加水印」免费吗？需要注册吗？Is the Add Watermark free? Do I need an account?

「PDF 加水印」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Add Watermark is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.