案例2：绘制按钮
main.cpp
#include<QApplication>
#include “demoWidget.h”
int main(int args , int argv)
{
QApplication app(args , argv);
DemoWidget w;
w.resize(400,400);
w.setVisible(true);
return app.exec();
}
main.pro
TEMPLATE=app
SOURCES=main.cpp demoWidget.cppdemoPushButton.cpp
HEADERS=demoWidget.h demoPushButton.h
CONFIG=release qt
QT=core gui
TARGET=main
demoWidget.h
#ifndef DEMO2_WIDGET_H
#define DEMO2_WIDGET_H
#include<QWidget>
#include “demoPushButton.h”
class DemoWidget: public QWidget
{
public:
DemoWidget(QWidget * parent=NULL);
public:
DemoPushButton * btn;
};
#endif
demoWidget.cpp
#include “demoWidget.h”
#include “demoPushButton.h”
DemoWidget::DemoWidget(QWidget *parent):QWidget(parent)
{
btn = new DemoPushButton(this);
btn->resize(100,30);
btn->move(100,100);
}
绘制按钮：
demoPushButton.h
#include<QPushButton>
#include<QPaintEvent>
#include<QMouseEvent>
#ifndef DEMO2_PUSHBUTTON_H
#define DEMO2_PUSHBUTTON_H
class DemoPushButton : public QPushButton
{
public:
DemoPushButton(QWidget * parent=NULL);
protected:
virtual void paintEvent(QPaintEvent * e);
virtual void enterEvent(QEvent * e);
virtual void leaveEvent(QEvent * e);
virtual void mouseEvent(QMouseEvent*e);
private:
bool israised;
};
#endif
demoPushButton.cpp
#include “demoPushButton”
#include<QColor>
#include<QBrush>
#include<QPen>
#include<QPoint>
#include<QPainter>
DemoPushButton::DemoPushButton(QWidget*parent)
:QPushButton(parent),israised(true)
{
setMouseTracking(true); //跟踪鼠标移动事件
}
void DemoPushButton::paintEvent(QPaintEvent* e)
{
//绘制按钮的边界
int w=width(); //按钮宽度
int h=height(); //按钮高度
QColor clrw(255,255,255);
QColor clrb(0,0,0);
QBrush brw(clrw);
QBrush brb(clrb);
QPen penw(brw,2);
QPen penb(brb,2);
QPoint pttop(w/2,0);
QPoint ptbottom(w/2,h);
QPoint ptleft(0,h/2);
QPoint ptright(w,h/2);
QPainter g(this);
if(israised)
{
g.setPen(penw);
}
else
{
g.setPen(penb);
}
g.drawLine(pttop,ptleft);
g.drawLine(pttop,ptright);
if(israised)
{
g.setPen(penb);
}
else
{
g.setPen(penw);
}
g.drawLine(ptbottom,ptleft);
g.drawLine(ptbotton,ptrright);
}
void DemoPushButton::enterEvent(QEvent * e)
{
israised=false;
repaint(); //重新绘制按钮
}
void DemoPushButton::leaveEvent(QEvent * e)
{
israised=true;
repaint();
}
void DemoPushButton::mouseEvent(QMouseEvent * e)
{
float w=this->width();
float h=this->height()
int x=e->x();
int y=e->y();
float k=h/w; //斜率
if( y>-k*x+h/2 &&
y>=k*x-h/2 &&
y<=k*x+h/2 &&
y<=-k*x+3*h/2)
{
israise=false;
}
else
{
israise=true;
}
repaint();
}