From 4cb91f3ac9a2d804ee39129f96e8754452c01826 Mon Sep 17 00:00:00 2001
From: iven <iven_h@qq.com>
Date: Thu, 4 Jun 2026 23:12:51 +0800
Subject: [PATCH] =?UTF-8?q?fix(app):=20=E4=BF=AE=E5=A4=8D=E6=89=93?=
 =?UTF-8?q?=E5=BC=80=E5=B7=B2=E4=BF=9D=E5=AD=98=E6=97=A5=E8=AE=B0=E6=97=B6?=
 =?UTF-8?q?=E7=AC=94=E8=BF=B9=E4=B8=8D=E5=8F=AF=E8=A7=81=20=E2=80=94=20syn?=
 =?UTF-8?q?cStrokes=20=E5=90=8E=E7=BC=BA=E5=B0=91=20setState?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

根因：_syncCacheAfterBuild 调用 _cache.syncStrokes() 后没有触发
setState，导致 CachedStrokesPainter 不知道缓存已更新，不执行重绘。

对比正常绘画流程（addStroke 后有 setState），加载笔迹流程遗漏了
重绘触发。添加 .then(() => setState) 后，合成图重建完成即刷新画布。
---
 app/lib/features/editor/widgets/handwriting_canvas.dart | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/app/lib/features/editor/widgets/handwriting_canvas.dart b/app/lib/features/editor/widgets/handwriting_canvas.dart
index bebdc31..53c336c 100644
--- a/app/lib/features/editor/widgets/handwriting_canvas.dart
+++ b/app/lib/features/editor/widgets/handwriting_canvas.dart
@@ -134,10 +134,15 @@ class _HandwritingCanvasState extends State<HandwritingCanvas> {
   }
 
   /// 在 build 完成后同步缓存（避免在 build 中触发异步操作）
+  ///
+  /// syncStrokes 重建合成图后必须调用 setState，
+  /// 否则 CachedStrokesPainter 不知道缓存已更新，不会触发重绘。
   void _syncCacheAfterBuild() {
     WidgetsBinding.instance.addPostFrameCallback((_) {
       if (!mounted) return;
-      _cache.syncStrokes(widget.strokes);
+      _cache.syncStrokes(widget.strokes).then((_) {
+        if (mounted) setState(() {});
+      });
     });
   }