1.预览图
2. 代码
头文件
#ifndef MOTORMETER_H #define MOTORMETER_H #include#include #include #include #include #include #include #include class motormeter : public QWidget { Q_OBJECT public: explicit motormeter(QWidget *parent = nullptr); ~motormeter(); protected: void paintEvent(QPaintEvent*); private: int degRotate =-120; private: void DrawPoint(QPainter&,int); void DrawDigital(QPainter&,int); void DrawCircle(QPainter&,int); void DrawSmallScale(QPainter&,int); void DrawBigScale(QPainter&,int); void DrawText(QPainter&,int); void DrawPointer(QPainter&,int); void drawIndicator(QPainter *painter); public slots: void valueChanged(int); }; #endif // MOTORMETER_H
源文件
#include "motormeter.h"
motormeter::motormeter(QWidget *parent) : QWidget(parent)
{
}
motormeter::~motormeter()
{
}
void motormeter::paintEvent(QPaintEvent*)
{
QPainter painter(this);
int width=this->width();
int height=this->height();
int radius=((width>height)?height:width)/2;
//移动画笔到中下方
painter.translate(width/2,height*0.6);
//启用反锯齿
painter.setRenderHint(QPainter::Antialiasing, true);
painter.setPen(Qt::NoPen);
//设置画刷颜色
painter.setBrush(QColor(138,43,226));
DrawPoint(painter,radius);
DrawDigital(painter,radius-10);
DrawCircle(painter,radius-35);
DrawSmallScale(painter,radius-60);
DrawBigScale(painter,radius-75);
DrawText(painter,radius/2);
DrawPointer(painter,radius-100);
}
//绘制外圈点
void motormeter::DrawPoint(QPainter& painter,int radius)
{
//组装点的路径图
QPainterPath pointPath;
pointPath.moveTo(-2,-2);
pointPath.lineTo(2,-2);
pointPath.lineTo(2,2);
pointPath.lineTo(0,4);
pointPath.lineTo(-2,2);
//绘制13个小点
for(int i=0;i<13;++i){
QPointF point(0,0);
painter.save();
painter.setBrush(QColor(255,127,80));
//计算并移动绘图对象中心点
point.setX(radius*qCos(((210-i*20)*M_PI)/180));
point.setY(radius*qSin(((210-i*20)*M_PI)/180));
//计算并移动绘图对象的中心点
painter.translate(point.x(),-point.y());
//计算并选择绘图对象坐标
painter.rotate(-120+i*20);
//绘制路径
painter.drawPath(pointPath);
painter.restore();
}
}
//绘制外圈数字，原理和绘制圆圈点一样
void motormeter::DrawDigital(QPainter& painter,int radius)
{
//设置画笔，画笔默认NOPEN
painter.setPen(QColor(218,112,214));
QFont font;
font.setFamily("Cambria");
font.setPointSize(15);
painter.setFont(font);
for(int i=0;i<13;++i){
QPointF point(0,0);
painter.save();
point.setX(radius*qCos(((210-i*20)*M_PI)/180));
point.setY(radius*qSin(((210-i*20)*M_PI)/180));
painter.translate(point.x(),-point.y());
painter.rotate(-120+i*20);
painter.drawText(-15, -5, 40, 30,Qt::AlignCenter,QString::number(i*20));
painter.restore();
}
//还原画笔
painter.setPen(Qt::NoPen);
}
//绘制外圈
void motormeter::DrawCircle(QPainter& painter,int radius)
{
//保存绘图对象
painter.save();
//计算大小圆路径
QPainterPath outRing;
QPainterPath inRing;
outRing.moveTo(0,0);
inRing.moveTo(0,0);
outRing.arcTo(-radius,-radius, 2*radius,2*radius,-31,242);
inRing.addEllipse(-radius+20,-radius+20,2*(radius-20),2*(radius-20));
outRing.closeSubpath();
//设置渐变色k
QRadialGradient radialGradient(0,0,radius,0,0);
radialGradient.setColorAt(0.93,QColor(138,43,226));
radialGradient.setColorAt(1,QColor(0,0,0));
//设置画刷
painter.setBrush(radialGradient);
//大圆减小圆
painter.drawPath(outRing.subtracted(inRing));
//painter.drawPath(outRing);
//painter.drawPath(inRing);
painter.restore();
}
//绘制刻度
void motormeter::DrawSmallScale(QPainter& painter,int radius)
{
//组装点的路径图
QPainterPath pointPath;
pointPath.moveTo(-2,-2);
pointPath.lineTo(-1,-4);
pointPath.lineTo(1,-4);
pointPath.lineTo(2,-2);
pointPath.lineTo(1,8);
pointPath.lineTo(-1,8);
//绘制121个小点
for(int i=0;i<121;++i){
QPointF point(0,0);
painter.save();
point.setX(radius*qCos(((210-i*2)*M_PI)/180));
point.setY(radius*qSin(((210-i*2)*M_PI)/180));
painter.translate(point.x(),-point.y());
painter.rotate(-120+i*2);
if(i>=90) painter.setBrush(QColor(250,0,0));
painter.drawPath(pointPath);
painter.restore();
}
}
//绘制刻度
void motormeter::DrawBigScale(QPainter& painter,int radius)
{
//组装点的路径图
QPainterPath pointPath1;
pointPath1.moveTo(-2,-2);
pointPath1.lineTo(-1,-4);
pointPath1.lineTo(1,-4);
pointPath1.lineTo(2,-2);
pointPath1.lineTo(1,8);
pointPath1.lineTo(-1,8);
QPainterPath pointPath2;
pointPath2.moveTo(-2,-2);
pointPath2.lineTo(-1,-4);
pointPath2.lineTo(1,-4);
pointPath2.lineTo(2,-2);
pointPath2.lineTo(1,15);
pointPath2.lineTo(-1,15);
//绘制25个刻度
for(int i=0;i<25;++i){
QPointF point(0,0);
painter.save();
point.setX(radius*qCos(((210-i*10)*M_PI)/180));
point.setY(radius*qSin(((210-i*10)*M_PI)/180));
painter.translate(point.x(),-point.y());
painter.rotate(-120+i*10);
if(i>=18) painter.setBrush(QColor(250,0,0));
if(i%2){
painter.drawPath(pointPath1);
}
else{
painter.drawPath(pointPath2);
}
painter.restore();
}
}
//绘制中心文字km/h
void motormeter::DrawText(QPainter& painter,int radius)
{
painter.save();
painter.setPen(QColor(153,51,250));
QFont font;
font.setFamily("Cambria");
font.setPointSize(16);
painter.setFont(font);
painter.drawText(-25, -radius, 60, 30,Qt::AlignCenter,QString("km/h"));
painter.restore();
}
//绘制指针
void motormeter::DrawPointer(QPainter& painter,int radius)
{
//组装点的路径图
QPainterPath pointPath;
pointPath.moveTo(10,0);
pointPath.lineTo(1,-radius);
pointPath.lineTo(-1,-radius);
pointPath.lineTo(-10,0);
pointPath.arcTo(-10,0,20,20,180,180);
QPainterPath inRing;
inRing.addEllipse(-5,-5,10,10);
painter.save();
QRadialGradient radialGradient(0,0,radius,0,0);
radialGradient.setColorAt(0,QColor(0,199,140,150));
radialGradient.setColorAt(1,QColor(255,153,18,150));
//计算并选择绘图对象坐标
painter.rotate(degRotate);
painter.setBrush(radialGradient);
painter.drawPath(pointPath.subtracted(inRing));
painter.restore();
}
void motormeter::valueChanged(int value)
{
this->degRotate = value;
update();
}
3. 用法
创建类，然后在创建的头文件和源文件里面添加上述代码
在UI界面里面拖拽widget部件
将widget部件提升为自定义的类，在提升的类名称里面填入上面源代码里面的类名
调用函数如下，在设计师界面类里面调用这个函数即可
void motormeter::valueChanged(int value)
{
this->degRotate = value;
update();
}
//设置背景墙 QPalette bgpal= palette(); bgpal.setColor(QPalette::Background,QColor(0,0,0)); setPalette (bgpal); ui->motormeter->valueChanged(a);
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