Qt+Opencv打开视频并播放，图像自适应缩放

#include "playvideo.h" #include "ui_playvideo.h" playvideo::playvideo(QWidget *parent) : QWidget(parent), ui(new Ui::playvideo) { ui->setupUi(this); timer=new QTimer(this); ui-> label_image->setScaledContents(true);//可以使图片完全按QWidget缩放，而不保持原视频比列 connect(timer,SIGNAL(timeout()),this,SLOT(ReadFrame())); } playvideo::~playvideo() { delete ui; } void playvideo::on_pushButton_open_clicked() { videofileName = QFileDialog::getOpenFileName( this, "open video", ".", "video (*.avi *.mp4 *.flv));;All files (*.*)"); sfileName = videofileName.toStdString(); video.open(sfileName); if(!video.isOpened()){ QMessageBox::information(this,tr("提示"),tr("视频没有打开")); } else { int videoW = int( video.get(CV_CAP_PROP_FRAME_WIDTH) ); int videoH = int( video.get(CV_CAP_PROP_FRAME_HEIGHT) ); fps = int( video.get(CV_CAP_PROP_FPS) ); //ui->widget_info->setVisible(true); //ui->widget_show->setVisible(true); ui->textBrowser_info->setText(QString("视频信息：%1").arg(videofileName)); ui->textBrowser_info->append(QString("视频尺寸：%2×%3").arg(videoW).arg(videoH)); ui->textBrowser_info->append(QString("视频帧率：%4").arg(fps)); Mat frame_start; video >> frame_start; ShowImage(frame_start); } } void playvideo::ShowImage(cv::Mat& mat) { //方法二，按比例缩放 QImage image=MatToQImage2(mat); QPixmap pixmap = QPixmap::fromImage(image); int width = ui->label_image->width(); int height = ui->label_image->height(); QPixmap fitpixmap = pixmap.scaled(width, height, Qt::KeepAspectRatio, Qt::SmoothTransformation); //按比例缩放 ui->label_image->setPixmap(fitpixmap); } void playvideo::on_pushButton_play_clicked() { timer->start(1000/fps); } void playvideo::on_pushButton_pause_clicked() { timer->stop(); } void playvideo::ReadFrame() { Mat frame_now; video >> frame_now;//读帧进frame if (frame_now.empty()) { QMessageBox::information(this, tr("warning"), tr("the video is end!")); timer->stop(); } else { ShowImage(frame_now); } } //图像格式转换 QImage playvideo::MatToQImage2(const cv::Mat &mat) { QImage img; int chana = mat.channels(); //依据通道数不同，改变不同的装换方式 if(3 == chana ){ //调整通道次序 cv::cvtColor(mat,mat,CV_BGR2RGB); img = QImage(static_cast<uchar *>(mat.data),mat.cols,mat.rows,QImage::Format_RGB888); }else if(4 == chana ){ //argb img = QImage(static_cast<uchar *>(mat.data),mat.cols,mat.rows,QImage::Format_ARGB32); }else { //单通道，灰度图 img = QImage( mat.cols, mat.rows , QImage::Format_Indexed8); uchar * matdata = mat.data; for(int row = 0 ; row <mat.rows ; ++row ) { uchar* rowdata = img.scanLine( row ); memcpy(rowdata,matdata ,mat.cols); matdata+=mat.cols; } } return img; }