QT自定义控件，以绘画板为列

来句名言：少壮不努力，老大送快递。

---------------------------------------------------------------------------------------------------那么我们开始吧----------------------------------------------------------------------------------------------

在我们写程序的时候有一些特殊的组件可能QT自带的无法满足要求，那么我们需要自定义一个控件come con来吧。

这是我写的绘画板的头.h

#ifndef DRAWBOARD_H_ 
#define DRAWBOARD_H_ 
#include <QWidget>
#include <QMouseEvent>
#include <QPaintEvent>
#include <QPainter>
#include "qdebug.h"
class DrawBoard:public QWidget
{
	Q_OBJECT
public:
	DrawBoard(QWidget *parent=0);
	void setBackgrpundPath(QString path);
	~DrawBoard();
protected:
	void mouseMoveEvent(QMouseEvent *event);
	void mousePressEvent(QMouseEvent *event);
	void paintEvent(QPaintEvent *event); 
	void resizeEvent(QResizeEvent *);
	void mouseReleaseEvent(QMouseEvent *);
private:
	QPen pen;
	enum{DRAW_START=0,DRAW_ING=1,DRAW_END=2};
	struct DrawLinePath{
		int startX;
		int startY;
		int endX;
		int endY;
	};
	int DRAW_STATUS = DRAW_END;
	QList<QPainterPath>paintPathList;
	QList<DrawLinePath> drawLinePathList;
	int startX, startY,endX,endY;
	QString backgroundPath;
	QColor color;
	QImage *image;
};
#endif

protected:
	void mouseMoveEvent(QMouseEvent *event);
	void mousePressEvent(QMouseEvent *event);
	void paintEvent(QPaintEvent *event); 
	void resizeEvent(QResizeEvent *);
	void mouseReleaseEvent(QMouseEvent *);

protected:是受保护的意思，重写这几个的意思是重写QWidget组件的四个虚函数，

那么我们再来看看.cpp文件

#include "drawboard.h"


DrawBoard::DrawBoard(QWidget*parent) :QWidget(parent)
{
	backgroundPath = "-1";
	setAttribute(Qt::WA_StaticContents);//自动缩放
	setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Maximum);
	image = new QImage(this->width(), this->height(), QImage::Format_Indexed8);
	image->fill(qRgba(0, 0, 0, 0));
	color == Qt::black; 
	pen.setWidth(10);
	pen.setCapStyle(Qt::RoundCap);
	pen.setJoinStyle(Qt::RoundJoin);
	pen.setStyle(Qt::SolidLine);
}//鼠标抬起事件
void DrawBoard::mouseReleaseEvent(QMouseEvent *event){
	repaint();
	DRAW_STATUS = DRAW_END;
	update();
}//窗体大小改变事件
void DrawBoard::resizeEvent(QResizeEvent *event){
	update();
} 
void DrawBoard::setBackgrpundPath(QString path){
	this->backgroundPath = path;
	image->load(path); 
	update();
}//窗体绘画事件
void DrawBoard::paintEvent(QPaintEvent *event){  
	//获取一个画笔对象  
	QPainter painter(this); 
	painter.setPen(pen);  
	painter.drawImage(rect(), *image);  
	switch (DRAW_STATUS){
	case DRAW_START:
		break;
	case DRAW_ING:
		 
	case  DRAW_END:   
		for (int i = 0; i < drawLinePathList.size(); i++){
			DrawLinePath drawlinePath = drawLinePathList.at(i);
			painter.drawLine(drawlinePath.startX, drawlinePath.startY, drawlinePath.endX, drawlinePath.endY);
		}
		 
		break;
	}  
}
void DrawBoard::mouseMoveEvent(QMouseEvent *event){
	
	if (event->buttons()&Qt::LeftButton){ 
		endX = event->x();//得到鼠标的X坐标
		endY = event->y();//得到鼠标的Y坐标
		qDebug() << event->x() << ",y:" << event->y();
		DRAW_STATUS = DRAW_ING;
		DrawLinePath drawlinePath{ startX, startY, endX, endY };
		drawLinePathList.push_back(drawlinePath);

		if (((endX - startX) > 1) || ((endY - startY) > 1))
		{
			repaint();
		}
		else{
			update();
		}
		startX = endX;
		startY = endY;
	}
	else if (event->buttons()&Qt::RightButton)
	{

	}
}
void DrawBoard::mousePressEvent(QMouseEvent *event){
	DRAW_STATUS = DRAW_START;
	if (event->button() == Qt::LeftButton){ 
		qDebug() << event->x() << ",y:" << event->y();
		startX = event->x();//得到鼠标的X坐标
		startY = event->y();//的到鼠标的Y坐标
	}
	else if (event->button() == Qt::RightButton)
	{ 

	}
}

DrawBoard::~DrawBoard()
{
}

/------------------end

这次的博客就在这里了，根据你自己的项目可以实现一些信号，和插槽等，根据项目来。

最后

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