Scaling QPixmap

AlvaroS

Hello everyone.
First of all thanks a lot for helping me and reading this post.

I have a jpeg image as a QPixmap in a scene.
I would like that the QPixmap has a specific size.

I try this:


            img_scene.scaledToHeight(my_height);
            img_scene.scaledToWidth(my_width);
            //img_scene.scaled(my_height,my_width);
            scene->addPixmap(img_scene);

but it works in the same way than if I do not write scaled...
Any idea to do that?

thanks a lot.

mrjj

@AlvaroS said:
Hi
Its a classic.
Scaled returns a copy ! it do not change the original.

img_scene = img_scene.scaled(my_height,my_width);

will do it.

kshegunov

@AlvaroS
Hello,
You're not actually changing the pixmap. Look at the documentation of QPixmap::scaledToHeight. Try something like this:

img_scene = img_scene.scaledToHeight(my_height);
img_scene = img_scene.scaledToWidth(my_width);

Kind regards.

AlvaroS

@mrjj said:

@AlvaroS said:
Hi
Its a classic.
Scaled returns a copy ! it do not change the original.

img_scene = img_scene.scaled(my_height,my_width);

will do it.

@kshegunov said:

@AlvaroS
Hello,
You're not actually changing the pixmap. Look at the documentation of QPixmap::scaledToHeight. Try something like this:
img_scene = img_scene.scaledToHeight(my_height);
img_scene = img_scene.scaledToWidth(my_width);
Kind regards.

Thanks a lot for answering me.
Now it works but not fine.

I have some items in my scene and I would like that items appear in foreground so over the QPixmap.

How can I do that?
Thanks again!!

mrjj

hi
try with
http://doc.qt.io/qt-5/qgraphicsitem.html#setZValue

AlvaroS

@mrjj Thanks a lot my friend!! It works!!!

Now I have another problem... sorry for being boring.

The image that I add is a irregular square, something like: http://www.maspa.se/SPANSKA/Matematica4/Geometria/Poligonos/Figuras/cuadrilatero1.gif

But in the scene if I write:
img_scene = img_scene.scaledToHeight(my_height);
img_scene = img_scene.scaledToWidth(my_width);

The image appears like a perfect regular square like: http://science-all.com/images/square/square-03.jpg

However if I do not write the scaled it appears fine....

Any ideas what am I doing wrong?!

Thanks a lot

mrjj

ehh
Im not sure how scaling the
polygon image could ever make it a rect !?!?

AlvaroS

@mrjj i don't know but it scales as a rect..

mrjj

@AlvaroS
try with other image. :)
just for test.

AlvaroS

@mrjj Yes!! It seems that "scaled" not scale whole image... maybe?

mrjj

@AlvaroS
Hmm i was think we only saw some of it ?
so it looked like rect. :)

AlvaroS

@mrjj Yes, it seems what I said yesterday, it does not scale the whole image...
Maybe I have to use a Qt::Transformation or something like that...
The other idea that I have watched on the internet is to use Qlabel, but I need to use Scene because I have items there...

AlvaroS

@mrjj said:

@AlvaroS
Hmm i was think we only saw some of it ?
so it looked like rect. :)

@AlvaroS said:

@mrjj Yes, it seems what I said yesterday, it does not scale the whole image...
Maybe I have to use a Qt::Transformation or something like that...
The other idea that I have watched on the internet is to use Qlabel, but I need to use Scene because I have items there...

I have tried this:

            img_scene=img_scene.scaled(my_height,my_width, Qt::IgnoreAspectRatio, Qt::FastTransformation);
            label_img->setPixmap(img_scene);
            label_img->setScaledContents(true);
            scene->addWidget(label_img)

But it works in the same way..