From 7c248d8ff9f0774a0bcdae019b2a8d65f4f9c13c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=88=98=E8=88=AA=E5=AE=87?= <3364451258@qq.com>
Date: Sat, 27 Jun 2026 14:56:44 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20ASCII=E6=B8=B2=E6=9F=93=E9=9D=99?=
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x < margin 时 mx 被 saturating_sub 截断为 0，导致读取 modules[0][*] 而不是渲染空白静区。
改为显式边界检查 x >= margin && x < margin+size，四边静区均为空白。
---
 core/src/render/ascii.rs | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/core/src/render/ascii.rs b/core/src/render/ascii.rs
index 9d2f2f4..83c353e 100644
--- a/core/src/render/ascii.rs
+++ b/core/src/render/ascii.rs
@@ -12,12 +12,11 @@ pub fn render_ascii(qr: &QrCode, invert: bool) -> String {
     let mut result = String::new();
     for y in 0..total {
         for x in 0..total {
-            let mx = x.saturating_sub(margin);
-            let my = y.saturating_sub(margin);
-            let is_dark = if mx < size && my < size {
-                qr.modules()[my][mx]
+            let in_qr = x >= margin && x < margin + size && y >= margin && y < margin + size;
+            let is_dark = if in_qr {
+                qr.modules()[y - margin][x - margin]
             } else {
-                false
+                false // 静区始终为亮色
             };
             result.push_str(if is_dark { dark_char } else { light_char });
         }