QT绘制自定义控件仪表盘代码

以下是一个简单的自定义仪表盘控件的示例代码，使用Qt绘制：

#include <QPainter>
#include <QWidget>

class Gauge : public QWidget {
public:
    Gauge(QWidget *parent = nullptr) : QWidget(parent) {}
    ~Gauge() {}

    void setValue(double value) {
        m_value = value;
        update();
    }

protected:
    void paintEvent(QPaintEvent *event) override {
        QPainter painter(this);

        // 绘制背景
        painter.fillRect(rect(), Qt::black);

        // 绘制刻度盘
        painter.setPen(Qt::white);
        int side = qMin(width(), height());
        int x = (width() - side) / 2;
        int y = (height() - side) / 2;
        painter.drawEllipse(x, y, side, side);

        // 绘制刻度线
        painter.save();
        painter.translate(width() / 2, height() / 2);
        for (int i = 0; i <= 360; i += 10) {
            painter.rotate(i);
            if (i % 30 == 0) {
                painter.drawLine(0, -side / 2, 0, -side / 2 + 20);
            } else {
                painter.drawLine(0, -side / 2, 0, -side / 2 + 10);
            }
            painter.rotate(-i);
        }
        painter.restore();

        // 绘制指针
        painter.setPen(Qt::red);
        painter.setBrush(Qt::red);
        painter.save();
        painter.translate(width() / 2, height() / 2);
        painter.rotate(-135 + m_value * 270 / 100);
        painter.drawPolygon(QPolygon({{-10, 0}, {0, -side / 2 + 20}, {10, 0}, {0, side / 10}}));
        painter.restore();
    }

private:
    double m_value = 0;
};

使用方法：

// 创建仪表盘控件
Gauge *gauge = new Gauge(this);
// 设置初始值
gauge->setValue(50);
// 将控件添加到布局中
layout->addWidget(gauge);