Qt第二周周二作业

代码：

widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>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 hslideValueChangedSlot(int);
private:Ui::Widget *ui;
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QPainter>
#include <QPen>
#include <QtCore/qmath.h>
Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);ui->horizontalSlider->setMaximum(300);ui->horizontalSlider->setMinimum(0);connect(ui->horizontalSlider,SIGNAL(valueChanged(int)),this,SLOT(hslideValueChangedSlot(int)));
}Widget::~Widget()
{delete ui;
}void Widget::paintEvent(QPaintEvent *event)
{QPainter p(this);//Qpainter:: translate()p.translate(this->width()/2,this->height()/2);p.setPen(Qt::NoPen);QBrush brush; brush.setColor(QColor(192,192,192)); brush.setStyle(Qt::SolidPattern);p.setBrush(brush);//外圆p.drawEllipse(-200,-200,400,400);QBrush brush1; brush1.setColor(QColor(0,0,0)); brush1.setStyle(Qt::SolidPattern);p.setBrush(brush1);//内圆p.drawEllipse(-170,-170,340,340);//直线p.rotate(ui->horizontalSlider->value());QPen pen; pen.setColor(QColor(255,255,255)); pen.setWidth(4); pen.setStyle(Qt::SolidLine);p.setPen(pen);p.drawLine(0,0,-120,120*sqrt(2));}void Widget::hslideValueChangedSlot(int)
{this->update();
}

运行截图：