[建议]QImage,QPixmap加载照片图像，切记处理拍摄方向 [复制链接]

QImage,QPixmap加载照片图像，切记处理拍摄方向

现在数码相机拍摄图片都有拍摄方向，水平、垂直拍摄，拍摄后，图像内容会保存相应的信息，我们可以获取这些信息，对图像做展示，不然你会发现，一张图片，90度拍摄后，QImage加载会发生90度旋转，我测试如果不做处理，html5的image标签，python的CV2模块加载图片，都会发现图片方向被旋转90度。再Qt中 可以用如下方式来修正图像方向
QImageReader reader(path);
        reader.setAutoTransform(true);
        const QImage newImage = reader.read();
        QImageIOHandler::Transformations transformation;
        if (newImage.isNull()) {
            QMessageBox::information(nullptr, QGuiApplication::applicationDisplayName(),
                tr("Cannot load %1: %2")
                .arg(QDir::toNativeSeparators(path), reader.errorString()));
            return;
        }
        else
        {
            transformation = reader.transformation();
            qDebug() << "transformation is " << transformation;
        }
if (transformation == QImageIOHandler::TransformationRotate90
            || transformation == QImageIOHandler::TransformationMirrorAndRotate90
            || transformation == QImageIOHandler::TransformationFlipAndRotate90
            || transformation == QImageIOHandler::TransformationRotate270)
        {
            QTransform matrix;
            matrix.rotate(90);
            m_pixmap = m_pixmap.transformed(matrix);
            m_image = m_image.transformed(matrix);
        }
        else if (transformation == QImageIOHandler::TransformationRotate180)
        {
            QTransform matrix;
            matrix.rotate(180);
            m_pixmap = m_pixmap.transformed(matrix);
            m_image = m_image.transformed(matrix);
        }