QImage to QPixmap where should I add scale() If I want to set to QLable

darrenleeleelee1

I want to do something like
but I use IgnoreAspectRatio, KeepAspectRatio, KeepAspectRatioByExpanding, three of them
are not wokring to my image, all of them are look same in my case.
What is the right to do it?

qimage = QtGui.QImage(arr.data, arr.shape[1], arr.shape[0], arr.shape[1]*2, QtGui.QImage.Format_Grayscale16).copy()
qimage = qimage.scaled(arr.shape[1], arr.shape[0], QtCore.Qt.KeepAspectRatio , QtCore.Qt.SmoothTransformation)
pixmap = QtGui.QPixmap.fromImage(qimage)
pixmap = pixmap.scaled(arr.shape[1], arr.shape[0], QtCore.Qt.IgnoreAspectRatio )
self.photo.setPixmap(pixmap)

mrjj

@darrenleeleelee1

Hi
I tried with the same sizes as you, found image at (2235, 3408) also

alt text

So not why you always seems to see the same.

What Qt version are you using ?

mrjj

Hi
Make sure your QLabel dont have ScaleContents set to true.

darrenleeleelee1

@mrjj I set true using self.photo.setScaledContents(True) But my image still not work.

SGaist

Hi,

That's what the @mrjjle answer suggested: do not set it to true if you want to handle the resize yourself.

mrjj

Hi
Also scaling the bitmap to its own size won't show anything

say if you had to labels
alt text

and we scale to them

auto qimage = QImage(":/2554644-middle.png");
    {
    qimage = qimage.scaled(ui->label->width(),ui->label->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation);
    auto pixmap = QPixmap::fromImage(qimage);
    ui->label->setPixmap(pixmap);
    }

    {
    qimage = qimage.scaled(ui->label->width(),ui->label->height(), Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
    auto pixmap = QPixmap::fromImage(qimage);
    ui->label_2->setPixmap(pixmap);
    }

alt text

then i think you can see effect of KeepAspectRatio and IgnoreAspectRatio

darrenleeleelee1

@SGaist ok.

darrenleeleelee1

@mrjj

qimage = QtGui.QImage(arr.data, arr.shape[1], arr.shape[0], arr.shape[1]*2, QtGui.QImage.Format_Grayscale16).copy()
        qimage = qimage.scaled(self.photo.width(), self.photo.height(), QtCore.Qt.IgnoreAspectRatio, QtCore.Qt.SmoothTransformation)
        pixmap = QtGui.QPixmap.fromImage(qimage)
        self.photo.setPixmap(pixmap)

did you mean this?But it still not wok.print(self.photo.hasScaledContents()) this return False.

mrjj

@darrenleeleelee1
Hi
hmm, I cant guess why.
for me, it clearly ignores the AspectRatio.

Maybe your picture is perfectly square?

darrenleeleelee1

@mrjj no, It's(2235, 3408)

mrjj

@darrenleeleelee1

ok.

what are
photo.width() and self.photo.height()

darrenleeleelee1

@mrjj (512, 512)

mrjj

@darrenleeleelee1

Hi
I tried with the same sizes as you, found image at (2235, 3408) also

alt text

So not why you always seems to see the same.

What Qt version are you using ?

darrenleeleelee1

@mrjj

You use scale for QImage not QPixmap?

mrjj

@darrenleeleelee1

Hi
Yes.

{
    qimage = qimage.scaled(ui->label->width(),ui->label->height(), Qt::KeepAspectRatio, Qt::SmoothTransformation);
    auto pixmap = QPixmap::fromImage(qimage);
    ui->label->setPixmap(pixmap);
    }

darrenleeleelee1

@mrjj What is the different if I am scale to QPixmap

mrjj

@darrenleeleelee1

Hi
as far as I know, nothing.
Both return a scaled copy.

I cant see anything wrong with the code you shown. So unless its a bug in 5.9.7
i really have no idea why the images look the same to you.

Also, you scale it down a lot so there should always be an effect.

darrenleeleelee1

@mrjj OK, thanks, I found I was not put two Image together like you do.And I miss the change.Thanks you alot.Sorry bother you.

mrjj

@darrenleeleelee1

ahh. Well that explains why they look so much the same :)
No worries, its no bother at all.