From 4e7b7734a7aad0e45164b0a3354270debeb94431 Mon Sep 17 00:00:00 2001
From: ZF sun <34314687@qq.com>
Date: Tue, 21 Apr 2026 09:16:56 +0800
Subject: [PATCH] =?UTF-8?q?fix(wechat):=20=E4=BF=AE=E5=A4=8D=20canvas=20?=
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---
 js/script.js | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/js/script.js b/js/script.js
index 845e75b..4ba2ee6 100644
--- a/js/script.js
+++ b/js/script.js
@@ -2068,7 +2068,6 @@
     // 生成画布（高清无损，保持与显示容器相同的宽高比）
     async function generateCanvas() {
         const canvas = exportCanvas;
-        const ctx = canvas.getContext('2d');
         const container = imageContainer;
 
         // 获取显示容器的实际尺寸和宽高比
@@ -2085,6 +2084,7 @@
         let TARGET_HEIGHT = Math.round(displayHeight * minScale);
         
         // 微信特殊处理：微信内置浏览器 canvas 限制更严格
+        // 实测微信中 canvas 最大尺寸约为 4096，但超过 2048 可能有问题
         const MAX_CANVAS_SIZE = isWechat() ? 2048 : 4096;
         
         // 如果超出限制，按宽高比等比例缩放
@@ -2126,7 +2126,18 @@
         // 设置画布为高清分辨率
         canvas.width = TARGET_WIDTH;
         canvas.height = TARGET_HEIGHT;
+        
+        // 微信中：验证 canvas 尺寸是否设置成功
+        if (isWechat() && (canvas.width !== TARGET_WIDTH || canvas.height !== TARGET_HEIGHT)) {
+            console.warn('Canvas 尺寸设置失败，使用实际尺寸:', canvas.width, 'x', canvas.height);
+            TARGET_WIDTH = canvas.width;
+            TARGET_HEIGHT = canvas.height;
+        }
+        
         console.log('实际画布尺寸:', canvas.width, 'x', canvas.height);
+        
+        // 获取 2d 上下文（必须在设置尺寸之后）
+        const ctx = canvas.getContext('2d');
 
         // 启用最高质量渲染
         ctx.imageSmoothingEnabled = true;
@@ -2139,7 +2150,7 @@
         // 计算从显示尺寸到目标分辨率的缩放比例
         // 使用统一的缩放比例，保持宽高比，确保所见即所得
         const scale = TARGET_WIDTH / displayWidth;
-        console.log('统一缩放比例:', scale);
+        console.log('统一缩放比例:', scale, '画布宽高比:', TARGET_WIDTH/TARGET_HEIGHT, '容器宽高比:', displayRatio);
 
         if (currentImage) {
             console.log('背景图原始尺寸:', currentImage.naturalWidth, 'x', currentImage.naturalHeight);