From 5a397e0b89238b15f9f54371dc8a650ec411164b Mon Sep 17 00:00:00 2001
From: tianzhendong <1203886034@qq.com>
Date: Thu, 18 Jun 2026 19:15:01 +0800
Subject: [PATCH] =?UTF-8?q?FIX:=E4=BF=AE=E5=A4=8D=E7=AC=AC=E4=B8=80?=
 =?UTF-8?q?=E6=AC=A1=E8=BE=93=E5=85=A5=E4=BC=9A=E6=B8=85=E7=A9=BA=E7=9A=84?=
 =?UTF-8?q?bug?=
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---
 numkeydia.cpp | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/numkeydia.cpp b/numkeydia.cpp
index 8be2553..ee4a152 100644
--- a/numkeydia.cpp
+++ b/numkeydia.cpp
@@ -224,6 +224,9 @@ void NumKeyDia::on_btn_back_clicked() {
     d->ui->lineEdit_input->setFocus();
 }
 
+// 数字/符号输入按钮统一入口：根据 QLineEdit 当前光标和选区执行插入或替换。
+// 设计意图：保持触屏软键盘与普通编辑框一致，首次输入不再隐式清空已有内容；
+// 边界条件：无选区时在光标处插入，部分/全部选中时仅替换选区，按钮信号在 GUI 线程内处理。
 void NumKeyDia::btn_input_clicked() {
     Q_D(NumKeyDia);
     auto *btn = qobject_cast<QPushButton *>(sender());
@@ -238,20 +241,31 @@ void NumKeyDia::btn_input_clicked() {
         return;
     }
 
-    if (d->m_firstInputFlag) {
-        d->ui->lineEdit_input->clear();
-        d->m_firstInputFlag = false;
-    }
-
-    QString input = btn->property("inputValue").toString();
+    const QString input = btn->property("inputValue").toString();
     if (input.isEmpty()) return;
 
-    int index = d->ui->lineEdit_input->cursorPosition();
+    // 数字键盘按钮点击发生在 GUI 线程内，这里只同步读取当前 QLineEdit 的光标和选区状态，
+    // 不缓存 QObject 指针到异步流程，避免弹窗复用时选区状态被旧的首次输入标记误清空。
     QString text = d->ui->lineEdit_input->text();
-    text.insert(index, input);
+    const int cursorIndex = d->ui->lineEdit_input->cursorPosition();
+    const bool hasSelection = d->ui->lineEdit_input->hasSelectedText();
+    const int selectionStart = d->ui->lineEdit_input->selectionStart();
+    const int selectedLength = d->ui->lineEdit_input->selectedText().size();
+    int insertIndex = cursorIndex;
+
+    if (hasSelection && selectionStart >= 0) {
+        // 有选区时仅替换选中范围；全选只是该规则的边界情况，不再依赖首次输入清空整行。
+        text.replace(selectionStart, selectedLength, input);
+        insertIndex = selectionStart;
+    } else {
+        // 无选区时保持普通编辑语义，在当前光标处插入，支持末尾追加和中间补字符。
+        text.insert(insertIndex, input);
+    }
+
+    d->m_firstInputFlag = false;
     d->ui->lineEdit_input->setText(text);
     d->ui->lineEdit_input->setFocus();
-    d->ui->lineEdit_input->setCursorPosition(index + input.size());
+    d->ui->lineEdit_input->setCursorPosition(insertIndex + input.size());
 }
 
 void NumKeyDia::closeKeyBoard() {