centralWidget有什么用
时间: 2023-06-11 09:09:37 浏览: 134
centralWidget是Qt框架中QWidget的一个属性,它是一个中心部件,可以用来容纳其他的QWidget(如QLabel、QLineEdit、QPushButton等),将它们组成一个可视化的界面。在一个窗口中,我们可以将centralWidget设置为一个QGridLayout、QVBoxLayout、QHBoxLayout等布局管理器,然后将需要显示的控件添加到这些布局管理器中,从而形成一个复杂的界面。使用centralWidget的好处是可以让我们集中管理窗口中的控件,便于代码的维护和开发。
相关问题
pyqt中代码self.label = QtWidgets.QLabel(self.centralwidget) self.label.setGeometry(QtCore.QRect(50, 50, 131, 51)) font = QtGui.QFont() font.setPointSize(12) self.label.setFont(font) self.label.setStyleSheet("border-rad
ius:15px;\n"
"background-color: rgb(255, 170, 127);")
这是做什么用的?能否简单解释一下代码的含义?
这段代码是在 PyQt 中创建一个 QLabel 对象,并设置其大小、字体、样式。具体来说,self.label 就是定义一个名为 label 的 QLabel 对象,而 self.centralwidget 是指父窗口中的 centralwidget 组件,即将这个 Label 放在主窗口的中央区域。其中 setGeometry() 方法设置了 label 的位置和大小,setFont() 方法设置了其字体大小,setStyleSheet() 方法设置了其样式,包括边框半径和背景颜色。
如何用qt的mainwindiw编写一个计算器代码
以下是一个简单的计算器代码示例,使用 Qt 的 QMainWindow 类:
```cpp
#include <QMainWindow>
#include <QGridLayout>
#include <QLineEdit>
#include <QPushButton>
class Calculator : public QMainWindow {
Q_OBJECT
public:
Calculator(QWidget *parent = nullptr) : QMainWindow(parent) {
QWidget *centralWidget = new QWidget(this);
setCentralWidget(centralWidget);
QGridLayout *gridLayout = new QGridLayout(centralWidget);
QLineEdit *lineEdit = new QLineEdit(centralWidget);
gridLayout->addWidget(lineEdit, 0, 0, 1, 4);
QPushButton *button0 = new QPushButton("0", centralWidget);
QPushButton *button1 = new QPushButton("1", centralWidget);
QPushButton *button2 = new QPushButton("2", centralWidget);
QPushButton *button3 = new QPushButton("3", centralWidget);
QPushButton *button4 = new QPushButton("4", centralWidget);
QPushButton *button5 = new QPushButton("5", centralWidget);
QPushButton *button6 = new QPushButton("6", centralWidget);
QPushButton *button7 = new QPushButton("7", centralWidget);
QPushButton *button8 = new QPushButton("8", centralWidget);
QPushButton *button9 = new QPushButton("9", centralWidget);
QPushButton *buttonPlus = new QPushButton("+", centralWidget);
QPushButton *buttonMinus = new QPushButton("-", centralWidget);
QPushButton *buttonMultiply = new QPushButton("*", centralWidget);
QPushButton *buttonDivide = new QPushButton("/", centralWidget);
QPushButton *buttonEquals = new QPushButton("=", centralWidget);
gridLayout->addWidget(button7, 1, 0);
gridLayout->addWidget(button8, 1, 1);
gridLayout->addWidget(button9, 1, 2);
gridLayout->addWidget(buttonPlus, 1, 3);
gridLayout->addWidget(button4, 2, 0);
gridLayout->addWidget(button5, 2, 1);
gridLayout->addWidget(button6, 2, 2);
gridLayout->addWidget(buttonMinus, 2, 3);
gridLayout->addWidget(button1, 3, 0);
gridLayout->addWidget(button2, 3, 1);
gridLayout->addWidget(button3, 3, 2);
gridLayout->addWidget(buttonMultiply, 3, 3);
gridLayout->addWidget(button0, 4, 0, 1, 2);
gridLayout->addWidget(buttonDivide, 4, 2);
gridLayout->addWidget(buttonEquals, 4, 3);
connect(button0, &QPushButton::clicked, this, [=] { addDigitToLineEdit("0"); });
connect(button1, &QPushButton::clicked, this, [=] { addDigitToLineEdit("1"); });
connect(button2, &QPushButton::clicked, this, [=] { addDigitToLineEdit("2"); });
connect(button3, &QPushButton::clicked, this, [=] { addDigitToLineEdit("3"); });
connect(button4, &QPushButton::clicked, this, [=] { addDigitToLineEdit("4"); });
connect(button5, &QPushButton::clicked, this, [=] { addDigitToLineEdit("5"); });
connect(button6, &QPushButton::clicked, this, [=] { addDigitToLineEdit("6"); });
connect(button7, &QPushButton::clicked, this, [=] { addDigitToLineEdit("7"); });
connect(button8, &QPushButton::clicked, this, [=] { addDigitToLineEdit("8"); });
connect(button9, &QPushButton::clicked, this, [=] { addDigitToLineEdit("9"); });
connect(buttonPlus, &QPushButton::clicked, this, [=] { addOperatorToLineEdit("+"); });
connect(buttonMinus, &QPushButton::clicked, this, [=] { addOperatorToLineEdit("-"); });
connect(buttonMultiply, &QPushButton::clicked, this, [=] { addOperatorToLineEdit("*"); });
connect(buttonDivide, &QPushButton::clicked, this, [=] { addOperatorToLineEdit("/"); });
connect(buttonEquals, &QPushButton::clicked, this, [=] { evaluateExpression(lineEdit->text()); });
}
private:
void addDigitToLineEdit(const QString &digit) {
QLineEdit *lineEdit = centralWidget()->findChild<QLineEdit *>();
lineEdit->insert(digit);
}
void addOperatorToLineEdit(const QString &op) {
QLineEdit *lineEdit = centralWidget()->findChild<QLineEdit *>();
lineEdit->insert(op);
}
void evaluateExpression(const QString &expression) {
QLineEdit *lineEdit = centralWidget()->findChild<QLineEdit *>();
lineEdit->setText(QString::number(eval(expression)));
}
int eval(const QString &expression) {
// TODO: Implement expression evaluation.
return 0;
}
};
int main(int argc, char *argv[]) {
QApplication app(argc, argv);
Calculator calculator;
calculator.show();
return app.exec();
}
#include "main.moc"
```
该代码创建了一个具有数字按钮、运算符按钮和等号按钮的简单计算器界面。当用户单击数字或运算符按钮时,该按钮的文本将插入到 QLineEdit 中。当用户单击等号按钮时,该表达式将计算并在 QLineEdit 中显示结果。
请注意,该代码尚未实现表达式求值的算法。你需要编写一个 eval() 函数来实现它,这超出了本答案的范围。