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

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

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);
    }

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

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.