Qt之简单绘图实现

#ifndef __XIMAGE__H__
#define __XIMAGE__H__
#include "qwidget.h"
#include<QPaintEvent>
#include<QMouseEvent>
#include<QColor>
#include<Qpen>
class XImage :
public QWidget
{
Q_OBJECT
public:
XImage(QWidget* parent=NULL);
~XImage();
void paintEvent(QPaintEvent* ev) override;
void mouseMoveEvent(QMouseEvent* ev) override;
void mouseReleaseEvent(QMouseEvent* ev) override;
public slots:
void Open();
void SetPen(int size,QColor col);
void SetErase(int size);
void Save();
private:
QImage src;
QPoint mpos;
QPen pen;
QImage img;
};
#endif

#include "XImage.h"
#include<QFileDialog>
#include "ui_XPS.h"
#include<QPainter>
XImage::XImage(QWidget* parent):QWidget(parent){}void XImage::Open()
{
QString filename = QFileDialog::getOpenFileName(this, QStringLiteral("打开图片"),
"",QStringLiteral("支持格式(*.png *.jpg)"));
if (filename.isNull())return;
if (!src.load(filename))return;
mpos = QPoint();
img = src.copy();
update();
}void XImage::mouseMoveEvent(QMouseEvent* ev)
{
QPainter painter(&img);
painter.setPen(pen);
if (mpos.isNull()) mpos = ev->pos();
painter.drawLine(QLine(mpos,ev->pos()));
mpos = ev->pos();
update();
}void XImage::SetPen(int size, QColor col)
{
pen.setWidth(size);
pen.setColor(col);
pen.setCapStyle(Qt::RoundCap);
pen.setJoinStyle(Qt::RoundJoin);
}void XImage::mouseReleaseEvent(QMouseEvent* ev)
{
mpos = QPoint();
}void XImage::paintEvent(QPaintEvent* ev)
{
QPainter painter(this);
painter.drawImage(0,0,img);
}void XImage::SetErase(int size)
{
pen.setWidth(size);
pen.setBrush(src);
}void XImage::Save()
{
QString filename = QFileDialog::getSaveFileName(this, QStringLiteral("打开图片"),
"", QStringLiteral("支持格式(*.png *.jpg)"));
if (filename.isNull())return;
if (!src.save(filename))return;
}XImage::~XImage(){}

#ifndef __XPS__H__
#define __XPS__H__#include <QtWidgets/QMainWindow>
#include "ui_XPS.h"
#include<QColor>
class XPS : public QMainWindow
{
Q_OBJECTpublic:
XPS(QWidget *parent = Q_NULLPTR);
public slots:
void SetPen();
void SetColor();
void SetErase();
void Save();
private:
Ui::XPSClass ui;
QColor col;
};
#endif

#include "XPS.h"
#include<QColorDialog>
#include<QButtonGroup>
XPS::XPS(QWidget *parent)
: QMainWindow(parent)
{
ui.setupUi(this); connect(ui.openaction,SIGNAL(triggered()),ui.Image,SLOT(Open()));
connect(ui.saveaction,SIGNAL(triggered()),ui.Image,SLOT(Save()));
col = QColor(250,0,0);
SetPen(); QButtonGroup* group = new QButtonGroup(this);
group->addButton(ui.penButton);
group->addButton(ui.eraseButton);
group->setExclusive(true);
}void XPS::SetPen()
{
ui.Image->SetPen(ui.pensize->value(),col);
ui.penButton->setChecked(true);
}void XPS::SetColor()
{
col = QColorDialog::getColor(Qt::red, this);
QString sty = QString("background-color:rgba(%1,%2,%3,%4)")
.arg(col.red()).arg(col.green()).arg(col.blue()).arg(col.alpha());
ui.colorButton->setStyleSheet(sty);
SetPen();
}void XPS::SetErase()
{
ui.Image->SetErase(ui.pensize->value());
ui.eraseButton->setChecked(true);
}void XPS::Save()
{
ui.Image->Save();
ui.statusBar->showMessage(QStringLiteral("保存结束"), 5000);
}

#include "XPS.h"
#include <QtWidgets/QApplication>int main(int argc, char *argv[])
{
QApplication a(argc, argv);
XPS w;
w.show();
return a.exec();
}