QT第二周周三

题目：使用图片绘制出仪表盘

代码：

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    void paintEvent(QPaintEvent* event) override;
    ~Widget();
public slots:
    void horizontalSliderValueChangedSlot();

private:
    Ui::Widget *ui;
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QPainter>

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    ui->horizontalSlider->setMaximum(100);
    ui->horizontalSlider->setMinimum(0);
    connect(ui->horizontalSlider,SIGNAL(valueChanged(int)),this,SLOT(horizontalSliderValueChangedSlot()));
}

void Widget::paintEvent(QPaintEvent *event)
{
    int size = 250;
    QPainter p(this);
    p.translate(this->width()/2,this->height()/2);
    p.drawPixmap(-size,-size,2*size,2*size,QPixmap(":/n/rs/Pan.png"));


    p.rotate(130+2.8*ui->horizontalSlider->value());
    p.drawPixmap(-27,-20,200,40,QPixmap(":/n/rs/Point.png"));
}



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



void Widget::horizontalSliderValueChangedSlot()
{
    update();
}

运行效果：