张宗平
05a685c952
- calculator_designer_ext（Day2 增强版：表达式求值 + 括号，递归下降解析器）接入 cmake - calculator_mainwindow（Day3 上午）：增强版计算器装进 QMainWindow， 菜单/状态栏/历史停靠窗，纯代码 + 显式 connect，与 mainwindow_showcase 形成坑卡对照 - calculator_mainwindow_qss（Day3 下午）：上午版 + QSS 双主题美化（按键分色/伪状态/深浅切换） - 验证 mainwindow_showcase（QMainWindow 六大组件综合演示，.ui + .qrc） - OUTLINE_4DAY.md / ASSIGNMENTS.md Day3 衔接增强版起点 + 参考实现指引 - 补提交 Day2 calculator/ 与 calculator_designer/ 参考实现（CMakeLists 已引用） - 全量构建 28/28，4 目标离屏自测退出码 0 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
235 lines
9.3 KiB
C++
235 lines
9.3 KiB
C++
// ============================================================================
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// qt_calculator —— Day2 下午案例参考实现：简易计算器
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// 对应教案：OUTLINE_4DAY.md Day2 下午「信号槽机制 → 项目案例：简易计算器」
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// 配套文档：docs/teaching/examples/calculator/README.md
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// 手工维护，非生成产物（同 student_manager/qthread_worker 等教学补充示例）。
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//
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// 教学重点（对应当天知识点，逐条在代码里标注）：
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// 1. 信号槽两种写法都用上：数字/运算符键用「lambda + this 作 context」批量
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// 绑定，等号/清空/退格键用「成员函数指针」绑定——当天两种写法都要会认；
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// 2. 所有 connect 只在构造函数里执行一次，不给「重复 connect 导致槽触发
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// 两次」的坑（当天★坑卡）留生长空间；
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// 3. QGridLayout 排键盘（布局原理 Day3 下午讲透，今天先用后学）；
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// 4. 中文/符号按钮文字用 QStringLiteral + 源文件 UTF-8，呼应当天编码坑卡。
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//
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// 离屏验证（自测模式）：QT_QPA_PLATFORM=offscreen tools/run_qt.sh qt_calculator
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// 自测流程：直接调用与按钮绑定的同一批处理函数（等价于点击），依次验证
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// 「7+3=」「6÷0=」「4.5+0.5=」「12 退格」「2+3+4= 链式运算」，全部通过退出码 0，
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// 任一步失败退出码 1。
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// ============================================================================
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#include <QApplication>
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#include <QDebug>
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#include <QGridLayout>
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#include <QLineEdit>
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#include <QPushButton>
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#include <QTimer>
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#include <QVBoxLayout>
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#include <QWidget>
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class Calculator : public QWidget {
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Q_OBJECT
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public:
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explicit Calculator(QWidget* parent = nullptr) : QWidget(parent) {
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setWindowTitle(QStringLiteral("简易计算器"));
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m_display = new QLineEdit(QStringLiteral("0"), this);
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m_display->setReadOnly(true); // 只显示结果，不接受直接键入
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m_display->setAlignment(Qt::AlignRight);
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auto* mainLayout = new QVBoxLayout(this);
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mainLayout->addWidget(m_display);
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mainLayout->addLayout(buildKeypad());
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}
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// 供自测直接调用，效果等价于点击对应按钮（同一批处理函数）。
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void onDigit(int digit) {
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if (m_error) onClear();
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if (m_startNew || m_display->text() == QStringLiteral("0")) {
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m_display->setText(QString::number(digit));
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m_startNew = false;
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} else {
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m_display->setText(m_display->text() + QString::number(digit));
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}
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}
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void onDot() {
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if (m_error) onClear();
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if (m_startNew) {
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m_display->setText(QStringLiteral("0."));
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m_startNew = false;
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return;
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}
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if (!m_display->text().contains(QLatin1Char('.')))
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m_display->setText(m_display->text() + QStringLiteral("."));
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}
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void onOperator(QChar op) {
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if (m_error) return;
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if (!m_startNew) compute(); // 连续按运算符：先把上一次算掉，再开始下一次（链式计算）
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m_pendingValue = m_display->text().toDouble();
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m_pendingOp = op;
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m_startNew = true;
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}
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void onEquals() {
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if (m_error) return;
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compute();
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m_pendingOp = QChar(); // 等号后清空待运算符：再按数字视为全新一次输入
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}
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void onClear() {
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m_display->setText(QStringLiteral("0"));
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m_pendingValue = 0.0;
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m_pendingOp = QChar();
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m_startNew = false;
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m_error = false;
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}
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void onBackspace() {
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if (m_error) { onClear(); return; }
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QString text = m_display->text();
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text.chop(1);
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m_display->setText(text.isEmpty() ? QStringLiteral("0") : text);
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}
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QString displayText() const { return m_display->text(); }
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private:
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QGridLayout* buildKeypad() {
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auto* grid = new QGridLayout; // 布局原理 Day3 下午讲透，今天先会用：行列坐标摆键盘
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addDigit(grid, 7, 0, 0); addDigit(grid, 8, 0, 1); addDigit(grid, 9, 0, 2);
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addOperator(grid, QStringLiteral("÷"), QLatin1Char('/'), 0, 3);
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addDigit(grid, 4, 1, 0); addDigit(grid, 5, 1, 1); addDigit(grid, 6, 1, 2);
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addOperator(grid, QStringLiteral("×"), QLatin1Char('*'), 1, 3);
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addDigit(grid, 1, 2, 0); addDigit(grid, 2, 2, 1); addDigit(grid, 3, 2, 2);
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addOperator(grid, QStringLiteral("-"), QLatin1Char('-'), 2, 3);
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addDigit(grid, 0, 3, 0);
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auto* btnDot = new QPushButton(QStringLiteral("."), this);
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grid->addWidget(btnDot, 3, 1);
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connect(btnDot, &QPushButton::clicked, this, [this] { onDot(); });
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// 等号/清空/退格各自唯一，用成员函数指针连接——信号槽的另一种常见写法。
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auto* btnEquals = new QPushButton(QStringLiteral("="), this);
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grid->addWidget(btnEquals, 3, 2);
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connect(btnEquals, &QPushButton::clicked, this, &Calculator::onEquals);
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addOperator(grid, QStringLiteral("+"), QLatin1Char('+'), 3, 3);
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auto* btnClear = new QPushButton(QStringLiteral("C"), this);
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grid->addWidget(btnClear, 4, 0);
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connect(btnClear, &QPushButton::clicked, this, &Calculator::onClear);
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auto* btnBackspace = new QPushButton(QStringLiteral("⌫"), this);
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grid->addWidget(btnBackspace, 4, 1);
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connect(btnBackspace, &QPushButton::clicked, this, &Calculator::onBackspace);
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return grid;
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}
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// 数字键：同一个槽 onDigit(int) 处理全部按钮，lambda 捕获各自的数字值，
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// 第五参数传 this 作 context——calculator 销毁时这些连接自动断开（当天坑卡）。
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void addDigit(QGridLayout* grid, int digit, int row, int col) {
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auto* btn = new QPushButton(QString::number(digit), this);
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grid->addWidget(btn, row, col);
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connect(btn, &QPushButton::clicked, this, [this, digit] { onDigit(digit); });
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}
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// 运算符键：同理，lambda + context，一个槽 onOperator(QChar) 处理全部。
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void addOperator(QGridLayout* grid, const QString& label, QChar op, int row, int col) {
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auto* btn = new QPushButton(label, this);
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grid->addWidget(btn, row, col);
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connect(btn, &QPushButton::clicked, this, [this, op] { onOperator(op); });
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}
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void compute() {
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if (m_pendingOp.isNull()) return; // 还没有待运算符（本次是第一个运算符）
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const double rhs = m_display->text().toDouble();
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double result = 0.0;
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if (m_pendingOp == QLatin1Char('+')) result = m_pendingValue + rhs;
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else if (m_pendingOp == QLatin1Char('-')) result = m_pendingValue - rhs;
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else if (m_pendingOp == QLatin1Char('*')) result = m_pendingValue * rhs;
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else if (m_pendingOp == QLatin1Char('/')) {
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if (rhs == 0.0) { showError(); return; } // 除零：不崩，给出明确的错误状态
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result = m_pendingValue / rhs;
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}
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m_display->setText(QString::number(result, 'g', 12));
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m_pendingValue = result;
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m_startNew = true;
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}
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void showError() {
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m_display->setText(QStringLiteral("Error"));
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m_error = true;
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m_startNew = true;
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}
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QLineEdit* m_display = nullptr;
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double m_pendingValue = 0.0;
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QChar m_pendingOp;
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bool m_startNew = false;
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bool m_error = false;
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};
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// ------------------------------------------------------------ 自测入口 ----
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static bool expectEqual(const char* label, const QString& actual, const QString& expected) {
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if (actual != expected) {
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qCritical() << "自测失败：" << label << "实际=" << actual << "预期=" << expected;
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return false;
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}
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qInfo() << "自测通过：" << label << "=>" << actual;
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return true;
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}
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static bool runSelfTest(Calculator* calc) {
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calc->onClear();
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calc->onDigit(7); calc->onOperator(QLatin1Char('+')); calc->onDigit(3); calc->onEquals();
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if (!expectEqual("7 + 3 =", calc->displayText(), QStringLiteral("10"))) return false;
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calc->onClear();
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calc->onDigit(6); calc->onOperator(QLatin1Char('/')); calc->onDigit(0); calc->onEquals();
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if (!expectEqual("6 ÷ 0 =", calc->displayText(), QStringLiteral("Error"))) return false;
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calc->onClear();
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calc->onDigit(4); calc->onDot(); calc->onDigit(5);
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calc->onOperator(QLatin1Char('+'));
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calc->onDigit(0); calc->onDot(); calc->onDigit(5);
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calc->onEquals();
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if (!expectEqual("4.5 + 0.5 =", calc->displayText(), QStringLiteral("5"))) return false;
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calc->onClear();
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calc->onDigit(1); calc->onDigit(2); calc->onBackspace();
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if (!expectEqual("12 退格", calc->displayText(), QStringLiteral("1"))) return false;
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calc->onClear();
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calc->onDigit(2); calc->onOperator(QLatin1Char('+'));
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calc->onDigit(3); calc->onOperator(QLatin1Char('+'));
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calc->onDigit(4); calc->onEquals();
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if (!expectEqual("2 + 3 + 4 =（链式运算）", calc->displayText(), QStringLiteral("9"))) return false;
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return true;
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}
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int main(int argc, char* argv[]) {
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QApplication app(argc, argv);
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Calculator calc;
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calc.resize(240, 320);
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calc.show();
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if (qgetenv("QT_QPA_PLATFORM") == "offscreen") {
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QTimer::singleShot(0, &calc, [&calc] {
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const bool ok = runSelfTest(&calc);
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QCoreApplication::exit(ok ? 0 : 1);
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});
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}
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return app.exec();
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}
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#include "qt_calculator.moc"
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