要求：使用QT绘图，完成仪表盘绘制，如下图。

素材

 

 运行效果：

代码： 

widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QPainter>
#include <QPen>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();void paintEvent(QPaintEvent *event) override;public slots:void horizontalSliderValueChangedSlot(int);private:Ui::Widget *ui;
};
#endif // WIDGET_H

 widget.cpp

#include "widget.h"
#include "ui_widget.h"Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);ui->horizontalSlider->setValue(0);ui->horizontalSlider->setMaximum(100);ui->horizontalSlider->setMinimum(0);connect(ui->horizontalSlider, SIGNAL(valueChanged(int) ), this, SLOT(horizontalSliderValueChangedSlot(int)));
}Widget::~Widget()
{delete ui;
}void Widget::paintEvent(QPaintEvent *event)
{QPainter p(this);double R  = this->width()*0.375;p.translate(this->width()/2,this->height()/2);p.drawPixmap(-R*1.01,-R*0.98,2*R,2*R,QPixmap(":/rs/Pan.png"));p.rotate(ui->horizontalSlider->value() * 2.8 + 130);p.drawPixmap(-R*0.08,-R*0.085,R*0.72,R*0.15,QPixmap(":/rs/Point.png"));}void Widget::horizontalSliderValueChangedSlot(int)
{this->update();
}

widget.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0"><class>Widget</class><widget class="QWidget" name="Widget"><property name="geometry"><rect><x>0</x><y>0</y><width>400</width><height>400</height></rect></property><property name="minimumSize"><size><width>400</width><height>400</height></size></property><property name="sizeIncrement"><size><width>0</width><height>0</height></size></property><property name="baseSize"><size><width>0</width><height>0</height></size></property><property name="windowTitle"><string>仪表盘</string></property><layout class="QVBoxLayout" name="verticalLayout"><property name="leftMargin"><number>100</number></property><property name="topMargin"><number>10</number></property><property name="rightMargin"><number>100</number></property><property name="bottomMargin"><number>10</number></property><item><spacer name="verticalSpacer"><property name="orientation"><enum>Qt::Vertical</enum></property><property name="sizeHint" stdset="0"><size><width>20</width><height>40</height></size></property></spacer></item><item><widget class="QSlider" name="horizontalSlider"><property name="orientation"><enum>Qt::Horizontal</enum></property></widget></item></layout></widget><resources/><connections/>
</ui>