Is this possible rotate Camera in GUI?

[haobo]

I test the Camera example from this website which is also the offical example of Qt.
It works but I want to do some processing on live-image like rotating ,cropping, inverse and so on. I read the Doc. the part of QCamera and QCameraviewfinder, but i did not find any functions which could enable these requiments. Am I missing something, or is this not possible. If this is not possible, is there another approach (like using the Opecv API?) Thanks in advance!

[Kent-Dorfman]

the best option is always to use a camera that can natively rotate the frame, to avoid having to do software filtering. based on OP feature request, I wouldn't consider Qt the place to do that stuff. Maybe openCV?

[Thomas Red]

To avoid using software filtering, it is usually preferable to utilize a camera that can rotate the frame naturally. I wouldn't think of Qt as the place to do that item based on the OP's feature request. perhaps openCV?

[zare]

@haobo it is easy.
create a class Inherits QAbstractVideoSurface as QCamera's viewfinder.
you can dowith images in this class.
next is my example:
frameprocess.h

#ifndef FRAMEPROCESS_H
#define FRAMEPROCESS_H

#include <QAbstractVideoSurface>

class FrameProcess : public QAbstractVideoSurface
{
    Q_OBJECT
public:
    explicit FrameProcess(QObject *parent = nullptr);
protected:
    QList<QVideoFrame::PixelFormat> supportedPixelFormats(QAbstractVideoBuffer::HandleType type) const;
    bool present(const QVideoFrame &frame);
signals:
    void sendIMG(QImage img);
};

#endif // FRAMEPROCESS_H

frameprocess.cpp

#include "frameprocess.h"

FrameProcess::FrameProcess(QObject *parent) : QAbstractVideoSurface(parent)
{
    this->setNativeResolution(QSize(800,600));
}

QList<QVideoFrame::PixelFormat> FrameProcess::supportedPixelFormats(QAbstractVideoBuffer::HandleType type) const
{
    QList<QVideoFrame::PixelFormat> pixelformats;
    pixelformats.append(QVideoFrame::Format_RGB32);
    pixelformats.append(QVideoFrame::Format_YUV420P);
    return pixelformats;
}

bool FrameProcess::present(const QVideoFrame &frame)
{
    QVideoFrame copy(frame);
    if(copy.isValid()){
        copy.map(QAbstractVideoBuffer::ReadOnly);
        QImage img(copy.bits(),copy.width(),copy.height(),QVideoFrame::imageFormatFromPixelFormat(copy.pixelFormat()));
        QMatrix mat;
        mat.rotate(180);
        img = img.transformed(mat,Qt::FastTransformation);
        emit sendIMG(img);
        return true;
    }
    return false;
}

widget.h

private:
    Ui::Widget *ui;
    QCamera *camera=Q_NULLPTR;
    QCameraImageCapture *imageCapture=Q_NULLPTR;
    FrameProcess *frame=Q_NULLPTR;

widget.cpp

camera = new QCamera(this);
    frame = new FrameProcess(this);
    connect(frame,&FrameProcess::sendIMG,this,&Widget::displayCamera);
    camera->setViewfinder(frame);