From 1c9d539653568f066e837ebdf71a52ba183b23f7 Mon Sep 17 00:00:00 2001
From: hmo <staymo7777@gmail.com>
Date: Mon, 27 Apr 2026 20:11:28 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20add=20watermark=20to=20generated=20PDF?=
 =?UTF-8?q?=20(=E4=BB=85=E4=BE=9B=E5=AD=A6=E4=B9=A0=E5=8F=82=E8=80=83,=20d?=
 =?UTF-8?q?iagonal,=20semi-transparent)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 app/services/pdf_generator.py | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/app/services/pdf_generator.py b/app/services/pdf_generator.py
index bb97230..7633bb6 100644
--- a/app/services/pdf_generator.py
+++ b/app/services/pdf_generator.py
@@ -11,6 +11,7 @@ from reportlab.platypus import (
 from reportlab.pdfbase import pdfmetrics
 from reportlab.pdfbase.ttfonts import TTFont
 from reportlab.lib.enums import TA_CENTER, TA_LEFT
+from reportlab.pdfgen import canvas as pdfcanvas
 
 # 注册中文字体
 # Windows 和 Linux 使用不同路径
@@ -269,5 +270,23 @@ def generate_pdf(plan_id, student_name, content, output_dir, rendered_report=Non
                 elif line:
                     pdf.add_paragraph(line)
 
-    doc.build(pdf.elements)
+    # 水印函数（每页都绘制）
+    def draw_watermark(c, doc):
+        if not CHINESE_FONT_OK:
+            return
+        c.saveState()
+        try:
+            c.setFont("Chinese", 14)
+            # 浅灰色半透明
+            c.setFillColor(colors.Color(0.6, 0.6, 0.6, alpha=0.25))
+            # 旋转45度
+            c.translate(A4[0]/2, A4[1]/2)
+            c.rotate(45)
+            # 绘制水印文字（居中）
+            c.drawCentredString(0, 0, "仅供学习参考")
+        except Exception:
+            pass  # 字体问题则跳过水印
+        c.restoreState()
+
+    doc.build(pdf.elements, onFirstPage=draw_watermark, onLaterPages=draw_watermark)
     return output_path
\ No newline at end of file