QT自绘滑动开关按钮

一、借鉴于飞杨青云的思想，进行修改：

1、使用鼠标妥当滑块，拖到左边为“关”，拖到右边为“开”。

2、释放鼠标时判断开关，并发射开、关状态信号。

3、关状态时滑块为黑色，拖动状态时为红色，开状态时滑块为蓝色。

二、类的封装：

#ifndef SWITCHBUTTON_H
#define SWITCHBUTTON_H

#include <QWidget>
#include <QPainter>
#include <QMouseEvent>

class SwitchButton : public QWidget
{
	Q_OBJECT

public:
	SwitchButton(QWidget *parent);
	~SwitchButton();

private:
	bool bSwitch;                     //开关状态:开true，关false

	QColor bgColorOn;                 //开状态时的背景颜色
	QColor bgColorOff;                //关状态时的背景颜色

	QColor sliderColor;               
	QColor sliderColorOn;             //开状态时滑块的背景颜色
	QColor sliderColorOff;            //关状态时滑块的背景颜色

	QColor textColorOn;               //开状态时文字颜色
	QColor textColorOff;              //关状态时文字颜色

	QString strText;                  //文字内容

	QPoint startPoint;                //滑块移动的起始点
	QPoint endPoint;                  //滑块移动的终点   
	QPoint centerPoint;               //滑块移动的中间某点

	int mouseX;           

	bool bPress;                      //左键是否按下

private:
	void paintEvent(QPaintEvent *e);
	void resizeEvent(QResizeEvent *e);
	void mousePressEvent(QMouseEvent *e);
	void mouseMoveEvent(QMouseEvent *e);
	void mouseReleaseEvent(QMouseEvent *e);
	void drawBg(QPainter& painter);        //绘制背景
	void drawSlidBlock(QPainter& painter); //绘制滑块
	void drawText(QPainter& painter);      //绘制文字

signals:
	void btnState(bool bswitch);
};

#endif // SWITCHBUTTON_H

#include "SwitchButton.h"
#include <QDebug>

SwitchButton::SwitchButton(QWidget *parent)
	: QWidget(parent)
{
	bSwitch = false;

	bgColorOff = QColor(192,192,192);
	bgColorOn = QColor(20,255,20);
	
	sliderColorOff = QColor(100, 100, 100);
	sliderColorOn = QColor(100, 184, 255);
	sliderColor = sliderColorOff;

	textColorOn = QColor(255,255,255);
	textColorOff = QColor(0,0,0);

	mouseX = 0;
	bPress = false;
}

SwitchButton::~SwitchButton()
{
}

void SwitchButton::mousePressEvent(QMouseEvent *e)
{
	if (e->button() == Qt::LeftButton)
	{
		if ((e->pos().x() - centerPoint.x())*(e->pos().y() - centerPoint.y()) <= ((rect().height()/2) * (rect().height()/2)))
		{
			bPress = true;
			mouseX = e->pos().x();
			sliderColor = QColor(160,30,30);
			update();
		}
	}
}

void SwitchButton::mouseMoveEvent(QMouseEvent *e)
{
	if (bPress)
	{
		if ((e->pos().x() >= startPoint.x()) && (e->pos().x() <= endPoint.x()))
		{
			int tempX = e->pos().x();
			centerPoint.setX(tempX - mouseX + centerPoint.x());
			mouseX = centerPoint.x();

			update();
		}
	}
}

void SwitchButton::mouseReleaseEvent(QMouseEvent *e)
{
	bPress = false;
	sliderColor = QColor(245,245,245);

	if (centerPoint.x() >= rect().width()/2)
	{
		centerPoint.setX(endPoint.x());
		sliderColor = sliderColorOn;

		if(!bSwitch)
			emit btnState(true);

		bSwitch = true;
	}
	else if (centerPoint.x() < rect().width()/2)
	{
		centerPoint.setX(startPoint.x());
		sliderColor = sliderColorOff;

		if(bSwitch)
			emit btnState(false);

		bSwitch = false;
	}

	update();
}

void SwitchButton::resizeEvent(QResizeEvent *e)
{
	startPoint = QPoint(rect().height()/2,rect().height()/2);
	centerPoint = startPoint;
	endPoint = QPoint((rect().right() - rect().height()/2),rect().height()/2);
}

void SwitchButton::paintEvent(QPaintEvent *e)
{
	QPainter painter(this);
	painter.setRenderHint(QPainter::Antialiasing);

	drawBg(painter);
	drawSlidBlock(painter);
	drawText(painter);
}

/*
** 绘制背景
*/
void SwitchButton::drawBg(QPainter& painter)
{
	painter.save();
	painter.setPen(Qt::NoPen);

	if (bSwitch)
	{
		painter.setBrush(QBrush(bgColorOn));
	} 
	else
	{
		painter.setBrush(QBrush(bgColorOff));
	}

	/*
	** 绘制按钮外边框
	*/
	QPainterPath path;
	int startX = rect().height()/2;
	int startY = rect().top();

	path.moveTo(startX,startY);
	path.arcTo(QRect(rect().left(),rect().top(),rect().height(),rect().height()),90,180);
	path.lineTo((rect().right() - startX),rect().height());
	path.arcTo(QRect((rect().right() - rect().height()),rect().top(),rect().height(),rect().height()),270,180);
	path.lineTo(startX,startY);
	painter.drawPath(path);

	painter.restore();
}

/*
** 绘制滑块
*/
void SwitchButton::drawSlidBlock(QPainter& painter)
{
	painter.save();
	painter.setPen(Qt::NoPen);

	painter.setBrush(QBrush(sliderColor));
	
	painter.drawEllipse(centerPoint,rect().height()/2 - 2,rect().height()/2 - 2);

	painter.restore();
}

void SwitchButton::drawText(QPainter& painter)
{
	painter.save();
	QFont font("Microsoft YaHei", 12, 50, false);
	painter.setFont(font);

	int x,y; 

	if (bSwitch)
	{
		painter.setPen(QPen(textColorOn));

		x = rect().left();
		y = rect().top();

		strText = QString::fromLocal8Bit("开");
	} 
	else
	{
		painter.setPen(QPen(textColorOff));
	
		x = rect().right() - rect().height();
		y = rect().top();

		strText = QString::fromLocal8Bit("关");
	}

	painter.drawText(x,y,rect().height(),rect().height(),Qt::AlignCenter,strText);

	painter.restore();
}

主框架调用：

#ifndef SWITCHBUTTONCLASS_H
#define SWITCHBUTTONCLASS_H

#include <QtGui/QWidget>
#include "ui_switchbuttonclass.h"

class SwitchButtonClass : public QWidget
{
	Q_OBJECT

public:
	SwitchButtonClass(QWidget *parent = 0, Qt::WFlags flags = 0);
	~SwitchButtonClass();

private:
	Ui::SwitchButtonClassClass ui;

private slots:
	void OnButtonState(bool bState);
};

#endif // SWITCHBUTTONCLASS_H

#include "switchbuttonclass.h"
#include <QMessageBox>

SwitchButtonClass::SwitchButtonClass(QWidget *parent, Qt::WFlags flags)
	: QWidget(parent, flags)
{
	ui.setupUi(this);
	connect(ui.widget,SIGNAL(btnState(bool)),this,SLOT(OnButtonState(bool)));
}

SwitchButtonClass::~SwitchButtonClass()
{

}

void SwitchButtonClass::OnButtonState(bool bState)
{
	if (bState)
	{
		QMessageBox::information(this,QString::fromLocal8Bit("开关状态"),QString::fromLocal8Bit("打开"));

	}else{
		QMessageBox::information(this,QString::fromLocal8Bit("开关状态"),QString::fromLocal8Bit("关闭"));
	}
}