Question

我需要裁剪QLabel上显示的QImage。我想用鼠标事件来做，比如在图像上拖动一个矩形，然后在释放事件上，图像应该裁剪为矩形的大小。我已经实现了这段代码：

void surf_detection::mousePressEvent(QMouseEvent *ev)
{
if(ui->label_2->underMouse()){
    cout <<"Entered Press"<<endl;
    origin = ev->pos();
    //if (!rubberBand)
        rubberBand = new QRubberBand(QRubberBand::Rectangle, this);

        rubberBand->show();
}
}

void surf_detection::mouseMoveEvent(QMouseEvent *ev)
{

rubberBand->setGeometry(QRect(origin, ev->pos()).normalized());                                                                                                              
}

void surf_detection::mouseReleaseEvent(QMouseEvent *ev)
{
QPoint a = mapToGlobal(origin);
QPoint b = ev->globalPos();

a = ui->label_2->mapFromGlobal(a);
b = ui->label_2->mapFromGlobal(b);
rubberBand->hide();
QPixmap OriginalPix(*ui->label_2->pixmap());
double sx = ui->label_2->rect().width();
double sy = ui->label_2->rect().height();
sx = OriginalPix.width() / sx;
sy = OriginalPix.height() / sy;

a.x = int(a.x * sx);
b.x = int(b.x * sx);
a.y = int(a.y * sy);
b.y = int(b.y * sy);

QRect myRect(a,b);

QImage newImage;
newImage = OriginalPix.toImage();

QImage copyImage;
copyImage = copyImage.copy(myRect);

ui->label_2->setPixmap(QPixmap::fromImage(copyImage));
ui->label_2->repaint();

}

但是这段代码在

给了我错误

a.x = int(a.x * sx);
b.x = int(b.x * sx);
a.y = int(a.y * sy);
b.y = int(b.y * sy);

错误：无效使用会员功能（你忘了＆＃39;（）＆＃39;？）

a.x = int（a.x * sx）; ^

我如何解决这个问题？

Answer 1

通过收听编译器：

a.setX(int(a.x() * sx));

在Qt中使用鼠标事件裁剪QImage

1 个答案: