cropping image on QLabel using mouseEvent

VRonin

QLabel is the wrong instrument for the job. have a look at this example: https://evileg.com/en/post/272/

mrjj

Hi
I think you used the wrong image by accident

you say

QImage newImage;
newImage = OriginalPix.toImage();
QImage copyImage;
copyImage = copyImage.copy(myRect); << copy empty

i think you meant.

QImage newImage;
newImage = OriginalPix.toImage();
QImage copyImage;
copyImage = newImage.copy(myRect); << copy from newImage

Dimple

@mjjj as u said i hv changed
copyImage=newImage.copy(myRect);

but here wat happens after dragged image,, its showing QLabel is completely black

mrjj

@Dimple
you mean when you drag the image to be cropped to the label ?

Dimple

yeah ,,after dragged the image ,,its showing QLabel is completely black (not shows image after cropped the image)

Dimple

mrjj

@Dimple
I think the mapping of the coordinates are a bit off so the rect copied is outside
the coordinates for label holding image.

Dimple

can u please send me correct code ,,,im not getting

mrjj

@Dimple
the calculations for the actual rect to copy

a = ui->label->mapFromGlobal(a);
b = ui->label->mapFromGlobal(b);

double sx = ui->label->rect().width();
double sy = ui->label->rect().height();

sx = OriginalPix.width() / sx;
sy = OriginalPix.height() / sy;

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

QRect myRect(a, b); // im not sure this rect is as intended.

try use qDebug to write it out and inspect the values.
like
qDebug() << " crop rect" << myRect;

fouad2130

This post is deleted!

Dimple

@mrjj

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

QRect myRect(a,b);

QImage newImage;
newImage = OriginalPix.toImage();
QImage copyImage;
copyImage=newImage.copy(myRect);
ui->label->setPixmap(QPixmap::fromImage(copyImage));
ui->label->setScaledContents(true);
ui->label->repaint();

now its working ,,i can crop the image but after cropped the image ,,,if i click on cropped image ,,image is disappearing?

mrjj

@Dimple
Hi
clicking the label triggers mousePressEvent and mouseReleaseEvent
so you will grab a very small /invalid area. ( thats my guess )

Dimple

@mrjj said in cropping image on QLabel using mouseEvent:

triggers

ok i ll change some functionality ,,Thanks for ur help

mrjj

@Dimple
Hi
i imagine a bool flag to tell it its in crop mode , else it will just ignore the mosuePress code etc.

Dimple

@mrjj

ok i ll check it out,,,thanks