手机培训网站建设北京百度推广电话号码

作业：

1：实现绘图的时候，颜色的随时调整

2：追加橡皮擦功能

3：配合键盘事件，实现功能

当键盘按 ctrl+z的时候，撤销最后一次绘图

头文件.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include<QMouseEvent>
#include<QPaintEvent>
#include<QPainter>
#include<QPen>
#include<QColor>
#include<QLine>
#include<QPoint>
#include<QPixmap>//图像容器
#include<QColorDialog>
#include<QStack>    //栈存储历史状态
#include<QKeyEvent>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();void mousePressEvent(QMouseEvent *event) override;
void mouseMoveEvent(QMouseEvent *event) override;
void paintEvent(QPaintEvent *event) override;
void keyPressEvent(QKeyEvent *event) override;private slots:
void on_pushButton_clicked();void on_pushButton_2_clicked();void on_pushButton_3_clicked();void on_pushButton_4_clicked();void on_pushButton_5_clicked();private:Ui::Widget *ui;QPoint p;QPainter painter;QPixmap *pix;QPen pen;QColor penColor;int penWidth;bool iseraser;QStack<QPixmap> historyStack;  // 历史画布栈
};
#endif // WIDGET_H

CPP

#include "widget.h"
#include "ui_widget.h"Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget),pix(new QPixmap(this->width(),this->height()))//实例化图纸大小及空间,penColor(Qt::green),penWidth(5),iseraser(false)
{ui->setupUi(this);//填充图纸颜色pix->fill();//fill默认白色
}Widget::~Widget()
{delete ui;delete pix;
}void Widget::mousePressEvent(QMouseEvent *event)
{historyStack.push(*pix);//保存当前画布状态p=event->pos();
}void Widget::mouseMoveEvent(QMouseEvent *event)
{//让画家在图纸上画画QPainter painter(pix);//实例化一支笔QPen pen;//(QColor("green"));if(iseraser){pen.setColor(Qt::white);pen.setWidth(30);}else{pen.setColor(penColor);pen.setWidth(penWidth);}//把笔给画家painter.setPen(pen);//让画家画线painter.drawLine(p,event->pos());//更新起始位置p=event->pos();//调用updata，触发绘制事件的发生this->update();}
void Widget::paintEvent(QPaintEvent *event)
{//实例化画家QPainter painter(this);//让画家画到窗口//让画家画图像，把第一个画家的画 画到窗口painter.drawPixmap(QPoint(0,0),*pix);
}void Widget::keyPressEvent(QKeyEvent *event)
{if (event->modifiers() == Qt::ControlModifier && event->key() == Qt::Key_Z){if (!historyStack.isEmpty()){*pix = historyStack.pop();  // 取出栈顶的历史画布this->update();  // 重新绘制界面}}
}void Widget::on_pushButton_clicked()
{//颜色QColor color=QColorDialog::getColor(penColor,this,"选择颜色");penColor=color;iseraser=false;}void Widget::on_pushButton_2_clicked()
{//粗细penWidth=5;iseraser=false;
}void Widget::on_pushButton_3_clicked()
{//粗细10penWidth=10;iseraser=false;
}void Widget::on_pushButton_4_clicked()
{//粗细20penWidth=20;iseraser=false;
}void Widget::on_pushButton_5_clicked()
{//橡皮iseraser= true;
}