用Qt实现标尺型仪表和圆盘型仪表核心代码，直动滑块和旋转滑块的实现

#include<QGraphicsScene> #include<QGraphicsSimpleTextItem> #include<QDebug> #include "widget.h" #include "ui_widget.h" #include"triangleslideritem.h" #include"trianglerotateitem.h" Widget::Widget(QWidget *parent) : QGraphicsView(parent) , ui(new Ui::Widget) { ui->setupUi(this); setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform); QGraphicsScene* scene=new QGraphicsScene(this); setScene(scene); scene->setSceneRect(-200,-200,400,400); setAlignment(Qt::AlignLeft | Qt::AlignTop); QLineF lineF(-100,-150,-100,200); scene->addLine(lineF,QPen(Qt::black)); { //直动型滑块(指向左侧） TriangleSliderItem* sliderItem=new TriangleSliderItem; sliderItem->setFixedXValue(-100); sliderItem->setBrush(QBrush(Qt::gray)); //三角滑块的填充颜色 sliderItem->setSize(15,16);//三角滑块的尺寸 sliderItem->setRange(lineF.p1().y(),lineF.p2().y());//三角滑块的滑动范围 scene->addItem(sliderItem); QGraphicsSimpleTextItem* text=new QGraphicsSimpleTextItem(sliderItem); text->setPos(0,-30); text->setPen(QPen(Qt::black)); text->hide(); //三角滑块在位置改变时，会发送位置的纵坐标值 connect(sliderItem,&TriangleSliderItem::sig_posYChanged,this,[=](double yValue) { qDebug()<<"TriangleSliderItem::sig_posYChanged"<<yValue; text->setText(QString("%1").arg(yValue,1,'f',2)); }); sliderItem->setPos(-100,-150); connect(sliderItem,&TriangleSliderItem::sig_pressChanged,this,[=](bool bPressed) { text->setVisible(bPressed); }); } { //直动型滑块(指向右侧） TriangleSliderItem* sliderItem=new TriangleSliderItem; sliderItem->setFixedXValue(-100); sliderItem->setDirection(); //设置指向右侧 sliderItem->setBrush(QBrush(Qt::blue)); //三角滑块的填充颜色 sliderItem->setSize(20,22);//三角滑块的尺寸 sliderItem->setRange(lineF.p1().y(),lineF.p2().y());//三角滑块的滑动范围 scene->addItem(sliderItem); QGraphicsSimpleTextItem* text=new QGraphicsSimpleTextItem(sliderItem); text->setPos(-60,-5); text->setPen(QPen(Qt::black)); text->hide(); //三角滑块在位置改变时，会发送位置的纵坐标值 connect(sliderItem,&TriangleSliderItem::sig_posYChanged,this,[=](double yValue) { qDebug()<<"TriangleSliderItem::sig_posYChanged"<<yValue; text->setText(QString("%1").arg(yValue,2,'f',1)); }); sliderItem->setPos(-100,-150); connect(sliderItem,&TriangleItem::sig_pressChanged,this,[=](bool bPressed) { text->setVisible(bPressed); }); } { double radius=150; QPointF _center(100,0); TriangleRotateItem* rotateItem=new TriangleRotateItem; rotateItem->setRotateCenter(_center); //设置滑块的旋转中心 rotateItem->setRotateRadius(radius); //设置滑块的旋转中心 scene->addItem(rotateItem); QGraphicsSimpleTextItem* text=new QGraphicsSimpleTextItem(rotateItem); text->setPos(22,-5); text->setPen(QPen(Qt::black)); text->hide(); connect(rotateItem,&TriangleRotateItem::sig_degree,this,[=](double degree) { text->setText(QString("%1°").arg(degree,1,'f',0)); }); rotateItem->setDegree(90);//设置滑块的角度 //滑块按下时，显示角度值 connect(rotateItem,&TriangleItem::sig_pressChanged,this,[=](bool bPressed) { text->setVisible(bPressed); }); QRectF rectF(0,0,2*radius,2*radius); rectF.moveCenter(_center); scene->addEllipse(rectF,QPen(Qt::black)); } } Widget::~Widget() { delete ui; }