QPainter刻度尺

一、

1.像温度计一样，动态往上，

二、

#ifndef RULERWIDGET_H
#define RULERWIDGET_H

#include <QObject>
#include <QWidget>

class RulerWidget : public QWidget
{
    Q_OBJECT
public:
    explicit RulerWidget(QWidget *parent = nullptr);

signals:

public slots:
public:
    void setValue(double value,int speed=50);
protected:
    void paintEvent(QPaintEvent *event) override;
private:
    int bar_speed_;
    int current_ruler_value_;
    int ruler_step_;
    int set_ruler_pix_;
    int warning_line_loc_pix_;
    void drawRuler(QPainter &p);
    void drawBarBackground(QPainter &p);
    void drawBar(QPainter &p);

};

#endif // RULERWIDGET_H

#include "rulerwidget.h"
#include <QPainter>
#include <QStyleOption>
#include <thread>

#include <QDebug>

const int RULER_SIZE_MIN=20;//刻度值在画布上范围，最小值，单位像素
const int RULER_SIZE_MAX=420;
const int RULER_SCALE_COUNT=50;//多少个刻度线，10个刻度线一个单位值
const int SCALE_LINE_LENGTH=20;//刻度线长度
const double WARNING_LINE_LOC=2.5;//警戒位置


RulerWidget::RulerWidget(QWidget *parent)
    : QWidget(parent)
    ,current_ruler_value_(RULER_SIZE_MAX)
{
    this->resize(500,500);
    this->setStyleSheet("QWidget{background-color:#808080;}");

    ruler_step_ = (RULER_SIZE_MAX-RULER_SIZE_MIN)/RULER_SCALE_COUNT;//刻度值0.1 多少个像素值
    warning_line_loc_pix_ = RULER_SIZE_MAX-WARNING_LINE_LOC*ruler_step_*10;//刻度值转换成刻度尺上的实际像素值
}

void RulerWidget::setValue(double value,int speed)
{

    bar_speed_=speed;
    set_ruler_pix_=RULER_SIZE_MAX-value*ruler_step_ *10;//刻度值转换成像素值
    qDebug()<<"px_value:"<<set_ruler_pix_;

    current_ruler_value_=RULER_SIZE_MAX;
    std::thread th=std::thread([&](){

        while(current_ruler_value_>set_ruler_pix_)
        {
           current_ruler_value_=current_ruler_value_-1;
           update();
           std::this_thread::sleep_for(std::chrono:: milliseconds (bar_speed_));
        }


    });
    th.detach();

}

void RulerWidget::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event)
    QStyleOption opt;
    opt.init(this);
    QPainter p(this);
    style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
    drawRuler(p);
    drawBarBackground(p);

    drawBar(p);
}

void RulerWidget::drawRuler(QPainter &p)
{

    int ruler_x=this->width()/2;
    p.setPen(QPen(Qt::white, 1, Qt::SolidLine, Qt::RoundCap));

    p.drawLine(ruler_x,RULER_SIZE_MIN,ruler_x,RULER_SIZE_MAX);



   int scale_line_x=ruler_x-SCALE_LINE_LENGTH;

   //qDebug()<<"ruler_step:"<<ruler_step;

   int scale_line_y=0;
   for(int i=0;i<=RULER_SCALE_COUNT;i++)
   {
     scale_line_y=RULER_SIZE_MAX-i*ruler_step_;
     if(i%5==0)
     {
         p.setPen(QPen(Qt::white, 2, Qt::SolidLine, Qt::RoundCap));
         p.drawLine(ruler_x,scale_line_y,scale_line_x-10,scale_line_y);
         p.drawText(scale_line_x-40,scale_line_y+5,QString::number((double)i/10.0,'f',1));

     }
     else
     {
         p.setPen(QPen(Qt::white, 1, Qt::SolidLine, Qt::RoundCap));
         p.drawLine(ruler_x,scale_line_y,scale_line_x,scale_line_y);
     }


   }


}

void RulerWidget::drawBarBackground(QPainter &p)
{

     int ruler_x=this->width()/2;
     p.setPen(QPen(QColor("#7FFFD4"), 20, Qt::SolidLine, Qt::FlatCap));
     p.drawLine(ruler_x+15,RULER_SIZE_MIN,ruler_x+15,RULER_SIZE_MAX);
}

void RulerWidget::drawBar(QPainter &p)
{
    int ruler_x=this->width()/2;

    if(current_ruler_value_<warning_line_loc_pix_)
    {

        p.setPen(QPen(QColor("#32CD32"), 20, Qt::SolidLine, Qt::FlatCap));
        p.drawLine(ruler_x+15,RULER_SIZE_MAX,ruler_x+15,warning_line_loc_pix_);

        p.setPen(QPen(QColor("#FF0000"), 20, Qt::SolidLine, Qt::FlatCap));
        p.drawLine(ruler_x+15,warning_line_loc_pix_,ruler_x+15,current_ruler_value_);
    }
    else
    {
        p.setPen(QPen(QColor("#32CD32"), 20, Qt::SolidLine, Qt::FlatCap));
        p.drawLine(ruler_x+15,RULER_SIZE_MAX,ruler_x+15,current_ruler_value_);
    }
    p.setPen(QPen(Qt::white, 1, Qt::SolidLine, Qt::RoundCap));
    p.drawText(ruler_x+35,current_ruler_value_,50,30,Qt::AlignLeft,QString::number((RULER_SIZE_MAX-current_ruler_value_)/(ruler_step_*10.0),'f',1));

}

标签：RulerWidget,int,ruler,void,RULER,刻度尺,QPainter,SIZE
来源： https://www.cnblogs.com/ike_li/p/13475397.html