详解Qt使用QImage类实现图像基本操作

public:
    QImage img;//原始图像

private slots:
    void on_Choose_clicked();

    void on_Rotate_clicked();

    void on_Zoom_clicked();

    void on_horizontalSlider_valueChanged(int value);

//选择图像
void Widget::on_Choose_clicked()
{
    QString path=QFileDialog::getOpenFileName(this,tr("选择图像"),"E:\\image\\",tr("Images (*.png *.bmp *.jpg *.tif *.GIF )"));
    if(path.isEmpty())
    {
         return;
    }
    else
    {
        if(! ( img.load(path) ) ) //加载图像
        {
            QMessageBox::information(this,tr("打开图像失败"),tr("打开图像失败!"));
            //delete img;
            return;
        }
        //img.load(path);
        ui->imagelabel->setPixmap(QPixmap::fromImage(img));
    }

}

//图像缩放
void Widget::on_Zoom_clicked()
{
    QImage* imgScaled = new QImage;
    int width=ui->imagelabel->width()/2;
    int height=ui->imagelabel->height()/2;
    *imgScaled=img.scaled(width,height,Qt::KeepAspectRatio);//对半缩放
    ui->imagelabel->setPixmap(QPixmap::fromImage(*imgScaled));
}

//图像旋转
void Widget::on_Rotate_clicked()
{
    ui->horizontalSlider->setVisible(true);//显示滑动条
}

//进度条值变化
void Widget::on_horizontalSlider_valueChanged(int value)
{
    qDebug()<<value;//输出旋转角度
    QImage* imgRatate = new QImage;
    QMatrix matrix;
    matrix.rotate(value);
    *imgRatate = img.transformed(matrix);
    ui->imagelabel->setPixmap(QPixmap::fromImage(*imgRatate));
}