1.概述

QwtCompass是Qwt库中的一个类，用于绘制一个指南针样式的仪表盘。它是基于QwtDial类的衍生类，提供了一些额外的功能和样式，用于显示方向和角度。

以下是类继承关系：

2.常用方法

void setScaleArc (double minArc, double maxArc) //设置弧度

void setLineWidth (int) //设置线宽

void setFrameShadow (Shadow) //设置边框样式

void setScaleDraw (QwtRoundScaleDraw *) //设置刻度值以及标签属性

void setNeedle (QwtDialNeedle *) //设置指针

void setRose (QwtCompassRose *rose) //设置rose

void setValue (double value) //设置当前值

3.示例

#ifndef COMPASSWIDGET_H
#define COMPASSWIDGET_H

#include <QWidget>

namespace Ui {
class CompassWidget;
}

class CompassWidget : public QWidget
{
    Q_OBJECT

public:
    explicit CompassWidget(QWidget *parent = 0);
    ~CompassWidget();

private:
    Ui::CompassWidget *ui;
};

#endif // COMPASSWIDGET_H


#include "CompassWidget.h"
#include "ui_CompassWidget.h"
#include "qwt_compass.h"
#include "qwt_dial_needle.h"
#include "qwt_compass_rose.h"
#include <QTimer>

static QPalette colorTheme( const QColor& base )
{
    QPalette palette;
    palette.setColor( QPalette::Base, base );
    palette.setColor( QPalette::Window, base.darker( 150 ) );
    palette.setColor( QPalette::Mid, base.darker( 110 ) );
    palette.setColor( QPalette::Light, base.lighter( 170 ) );
    palette.setColor( QPalette::Dark, base.darker( 170 ) );
    palette.setColor( QPalette::Text, base.darker( 200 ).lighter( 800 ) );
    palette.setColor( QPalette::WindowText, base.darker( 200 ) );

    return palette;
}

CompassWidget::CompassWidget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::CompassWidget)
{
    ui->setupUi(this);

    setPalette( colorTheme( QColor( Qt::darkGray ).darker( 150 ) ) );

    QwtCompass *compass = new QwtCompass(this);
    compass->setScaleArc( 0.0, 360.0 );

    ui->verticalLayout->addWidget(compass);

    // 设置圆环的宽度
    compass->setLineWidth(4);

    // 设置圆环的样式
    compass->setFrameShadow(QwtCompass::Raised);

    // 设置刻度值以及标签属性
    QwtCompassScaleDraw *scaleDraw = new QwtCompassScaleDraw();
    scaleDraw->enableComponent(QwtAbstractScaleDraw::Ticks,true);       // 显示刻度尺
    scaleDraw->enableComponent(QwtAbstractScaleDraw::Labels,true);      // 显示文字标签
    scaleDraw->enableComponent(QwtAbstractScaleDraw::Backbone,false);   // 刻度尺圆环是否连续

    scaleDraw->setTickLength(QwtScaleDiv::MinorTick,0);
    scaleDraw->setTickLength(QwtScaleDiv::MediumTick,0);
    scaleDraw->setTickLength(QwtScaleDiv::MajorTick,3);
    scaleDraw->setPenWidthF(1);

    compass->setScaleDraw(scaleDraw);

    // 添加指针
    compass->setNeedle(new QwtCompassMagnetNeedle(QwtCompassMagnetNeedle::TriangleStyle, Qt::white, Qt::red));
    compass->setValue(180);

    //设置rose
//    QwtSimpleCompassRose *rose = new QwtSimpleCompassRose(8,1);
//    compass->setRose(rose);


    QTimer *timer = new QTimer(this);
    timer->start(1000);
    connect(timer,&QTimer::timeout,[=]{
        double value = qrand() % 360;
        compass->setValue(value);
    });
}

CompassWidget::~CompassWidget()
{
    delete ui;
}