之前写过用重写QGraphicsItem的方式来实现图片显示，框选，保存的代码，这次通过重写QLabel的方式来实现。
主要重写QLabel的代码如下：
mylabel.h
#ifndef MYLABEL_H
#define MYLABEL_H
#include <QObject>
#include <QWidget>
#include <QLabel>
#include <QMouseEvent>
#include <QPainter>
class myLabel:public QLabel
{
Q_OBJECT
public:
myLabel(QWidget *parent);
~myLabel();
QPixmap m_loadPixmap;
QPixmap m_capturePixmap;
void mousePressEvent(QMouseEvent *e) Q_DECL_OVERRIDE;
void mouseMoveEvent(QMouseEvent *e) Q_DECL_OVERRIDE;
void mouseReleaseEvent(QMouseEvent *e) Q_DECL_OVERRIDE;
void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;
private:
bool m_isDown;
QPoint m_start;
QPoint m_stop;
QRect getRect(const QPoint &beginPoint, const QPoint &endPoint);
Q_SIGNALS:
void getPictureSig(QPixmap catureImage);
};
#endif // MYLABEL_H
mylabel.cpp
#include "mylabel.h"
myLabel::myLabel(QWidget *parent):QLabel(parent),m_start(QPoint(-1,-1)),m_stop(QPoint(-1,-1))
{
}
myLabel::~myLabel()
{
}
void myLabel::mousePressEvent(QMouseEvent *e)
{
if(e->button() && Qt::LeftButton){
m_isDown = true;
m_start = e->pos();
m_stop = e->pos();
}
}
void myLabel::mouseMoveEvent(QMouseEvent *e)
{
if(m_isDown){
m_stop = e->pos();
}
update();
}
void myLabel::mouseReleaseEvent(QMouseEvent *e)
{
if(e->button() && Qt::LeftButton){
m_isDown = false;
QRect selectedRect = getRect(m_start, m_stop);
m_capturePixmap = m_loadPixmap.copy(selectedRect);
emit getPictureSig(m_capturePixmap);//将框选的图片传给主界面
}
}
void myLabel::paintEvent(QPaintEvent * event )
{
QLabel::paintEvent(event);
QPainter painter(this);
painter.setPen(QPen(Qt::green,2));
if(!m_isDown){
return;
}
painter.drawRect(QRect(m_start,m_stop));
}
QRect myLabel::getRect(const QPoint &beginPoint, const QPoint &endPoint)
{
int x, y, width, height;
width = qAbs(beginPoint.x() - endPoint.x());
height = qAbs(beginPoint.y() - endPoint.y());
x = beginPoint.x() < endPoint.x() ? beginPoint.x() : endPoint.x();
y = beginPoint.y() < endPoint.y() ? beginPoint.y() : endPoint.y();
QRect selectedRect = QRect(x, y, width, height);
// 避免宽或高为零时拷贝截图有误;
if (selectedRect.width() == 0)
{
selectedRect.setWidth(1);
}
if (selectedRect.height() == 0)
{
selectedRect.setHeight(1);
}
return selectedRect;
}
#include "mainwindow.h"
```
```
#include "ui_mainwindow.h"
```
```
#pragma execution_character_set("utf-8")//让能够正常显示中文字符串
```
```
MainWindow::MainWindow(QWidget *parent) :
```
```
QMainWindow(parent),
```
```
ui(new Ui::MainWindow)
```
```
{
```
```
ui->setupUi(this);
```
```
label = new myLabel(this);
```
```
//label->setGeometry(180,100,750,550);//设置label位置大小
```
```
label->setText("Please Load Picture !");//显示文字
```
```
label->setAlignment(Qt::AlignCenter);//文字水平垂直居中
```
```
label->setStyleSheet("QLabel{background-color:rgb(200,200,200);}");//通过样式表设置背景色
```
```
ui->verticalLayout->addWidget(label);
```
```
QObject::connect(label,&myLabel::getPictureSig,this,&MainWindow::recvPicture);
```
```
}
```
```
```
```
MainWindow::~MainWindow()
```
```
{
```
```
delete ui;
```
```
}
```
```
```
```
void MainWindow::on_pushButton_clicked()//打开文件
```
```
{
```
```
QFileDialog *fileDlg = new QFileDialog(this);
```
```
fileDlg->setWindowTitle("Choose Pictures");
```
```
QStringList qstrFilters;
```
```
qstrFilters<<"Image files(*.bmp *.jpg *.pbm *.pgm *.png *.ppm *.xbm *.xpm)";
```
```
qstrFilters<<"Any files (*)";
```
```
fileDlg->setNameFilters(qstrFilters);//设置文件过滤器
```
```
fileDlg->setFileMode(QFileDialog::ExistingFile);//设置一次只能选中一个文件
```
```
if(fileDlg->exec() == QDialog::Accepted)
```
```
{
```
```
QStringList lstName = fileDlg->selectedFiles();
```
```
if(lstName.count()>0)//有选中的文件
```
```
{
```
```
ui->textEdit->setText(lstName.at(0));
```
```
QImage img = QImage(lstName.at(0));
```
```
QPixmap tempPix=QPixmap::fromImage(img);
```
```
label->setPixmap(tempPix);
```
```
label->resize(label->pixmap()->size());
```
```
// QPixmap fitpixmap = QPixmap::fromImage(img).scaled(label->width(), label->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation); // 按比例缩放
```
```
// label->setPixmap(fitpixmap);
```
```
label->m_loadPixmap = tempPix;//QPixmap::grabWindow(label->winId()); // 抓取label窗口为复制区域
```
```
}
```
```
}
```
```
fileDlg->close();
```
```
delete fileDlg;
```
```
fileDlg = nullptr;
```
```
}
```
```
```
```
void MainWindow::on_pushButton_2_clicked()//新增ROI区域
```
```
{
```
```
lstPixmapROI.append(crtPixmapROI);
```
```
for(int i = 0;i<lstPixmapROI.count();i++)
```
```
{
```
```
//lstPixmapROI[i].save("D://test.png");
```
```
if(i ==0)
```
```
{
```
```
QPixmap fitpixmap = lstPixmapROI[i].scaled(ui->labelROI1->width(), ui->labelROI1->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation); //按比例缩放
```
```
ui->labelROI1->setPixmap(fitpixmap);
```
```
}
```
```
if(i ==1)
```
```
{
```
```
QPixmap fitpixmap = lstPixmapROI[i].scaled(ui->labelROI2->width(), ui->labelROI2->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation); //按比例缩放
```
```
ui->labelROI2->setPixmap(fitpixmap);
```
```
}
```
```
if(i ==2)
```
```
{
```
```
QPixmap fitpixmap = lstPixmapROI[i].scaled(ui->labelROI3->width(), ui->labelROI3->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation); // 按比例缩放
```
```
ui->labelROI3->setPixmap(fitpixmap);
```
```
}
```
```
if(i ==3)
```
```
{
```
```
QPixmap fitpixmap = lstPixmapROI[i].scaled(ui->labelROI4->width(), ui->labelROI4->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation); // 按比例缩放
```
```
ui->labelROI4->setPixmap(fitpixmap);
```
```
}
```
```
if(i ==4)
```
```
{
```
```
QPixmap fitpixmap = lstPixmapROI[i].scaled(ui->labelROI5->width(), ui->labelROI5->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation); // 按比例缩放
```
```
ui->labelROI5->setPixmap(fitpixmap);
```
```
}
```
```
}
```
```
label->update();
```
```
}
```
```
```
```
void MainWindow::recvPicture(QPixmap pix)
```
```
{
```
```
crtPixmapROI = pix;
```
```
}
```
```
```
```
void MainWindow::on_pushButton_3_clicked()//批量保存ROI区域
```
```
{
```
```
QString strFileName = QFileDialog::getSaveFileName(this,tr("Save Picture"),"","PNG(*.png);;JPG(*.jpg);;BMP(*.bmp)");
```
```
for(int i = 0;i<lstPixmapROI.count();i++)
```
```
{
```
```
QString strNum = QString("%1").arg(i,4,10,QLatin1Char('0'));//0001保留4位数字，i之前自动补零
```
```
int nIndex = strFileName.lastIndexOf('.');//寻找‘.’符号在字符串中的id
```
```
QString strName0 = strFileName.left(nIndex);
```
```
if(lstPixmapROI.count()>1)
```
```
{
```
```
strName0 += strNum;
```
```
}
```
```
nIndex++;
```
```
int nLen = strFileName.length()-nIndex;
```
```
QString strSuffix = strFileName.right(nLen);//截取‘.’符号后面的字符串，这是为了获取文件后缀名
```
```
strName0 += "."+strSuffix;
```
```
//QPixmap pix = QPixmap(m_strPathList[i]);
```
```
lstPixmapROI[i].save(strName0,strSuffix.toUpper().toUtf8());
```
```
}
```
```
}
```
```
