[英]Cropping a QImage using Mouse Events in Qt
我需要裁剪显示在QLabel上的QImage。 我想用mouseevents做到这一点,例如在图像上拖动一个矩形,然后在releaseevent上,图像应裁剪为矩形的大小。 我已经实现了以下代码:
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();
}
但是这段代码给我错误
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:成员函数无效使用(您忘记了'()'吗?)
ax = int(ax * sx); ^
我该如何解决?
通过听您的编译器:
a.setX(int(a.x() * sx));
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