Issues with QScrollArea and custom widget

[SGaist]

Hi,

Might be a silly question but how are you handling UGfxDisplay ?

[Joel Bodenmann]

@kshegunov said in Issues with QScrollArea and custom widget:

Well, something moved at least. Can you get the paint rects you get when zoomin in/out and when you scroll up/down/left/right along with the image rects and dump them all into a file?

Sure, I'll get that done.

@SGaist said in Issues with QScrollArea and custom widget:

Might be a silly question but how are you handling UGfxDisplay ?

I'm sorry, I don't understand what handling means in this context. Can you be more specific?

[SGaist]

Are you calling something like _centralScrollArea->setWidget(_myGDisplay); ?

Then, are you sure that you should handle the scaling in GDisplay ?

When zooming, what about having something like _myGDisplay->resize(_scale * _sourceSize); So you only handle painting in that widget.

[Joel Bodenmann]

@kshegunov said in Issues with QScrollArea and custom widget:

Well, something moved at least. Can you get the paint rects you get when zoomin in/out and when you scroll up/down/left/right along with the image rects and dump them all into a file?

Here you go: http://paste.ugfx.io/show/a5113bcc08

@SGaist said in Issues with QScrollArea and custom widget:

Are you calling something like _centralScrollArea->setWidget(_myGDisplay); ?

Yep, that's what I am doing.

@SGaist said in Issues with QScrollArea and custom widget:

When zooming, what about having something like _myGDisplay->resize(_scale * _sourceSize); So you only handle painting in that widget.

In my opinion that won't work as it will not scale up the contents inside of my UGfxDisplay. Keep in mind that the QPixmap I draw in my UGfxDisplay::paintEvent() is the content of a virtual display. That virtual display has a given size (width and height) in pixels. When zooming in I need to scale up everything. I don't display more of the widget, I just display the same content bigger.

[kshegunov]

Have you noticed your image doesn't grow (or shrink)?

[Joel Bodenmann]

The image is not supposed to grow. The image represents the contents of the virtual display. It will always have the same amount of pixels no matter how much I zoom into the UGfxDisplay widget. My virtual display does not grow by zooming into it :p

[kshegunov]

But why are you redrawing reinitializing it at each paint event then? It got me confused, now I believe I know what you want. Should be something like this (I *think*):

painter.drawImage(event->rect(), img, event->rect() / _scale);

PS. Or not. I need to think.
PS. After thinking:

QRect paintRect = event->rect();
QRect sourceRect(paintRect.topLeft() / _scale, paintRect.size() / _scale);
painter.drawImage(paintRect, img, sourceRect);

[Joel Bodenmann]

Wooo, I love you \o/ (still, not again, don't worry honey)

This is with your "After thinking" code: https://www.screencast.com/t/cEAa2z4Zd

In retrospect this seems somewhat obvious...

[kshegunov]

@Joel-Bodenmann said in Issues with QScrollArea and custom widget:

Wooo, I love you

Nice! Love and world peace and such things. ;)

In retrospect this seems somewhat obvious...

Yes, quantum mechanics also seems rather obvious to me ... after a few people thought and invented it. ;)

[Joel Bodenmann]

@kshegunov said in Issues with QScrollArea and custom widget:

Yes, quantum mechanics also seems rather obvious to me ... after a few people thought and invented it. ;)

invented? ;)
Too bad those people didn't teach you how to write nice code though :p

Thank you for your help guys, much appreciated!

[kshegunov]

@Joel-Bodenmann said in Issues with QScrollArea and custom widget:

Too bad those people didn't teach you how to write nice code though :p

This is all a fault of my own, sadly, but hey life's not all roses ... :)

Thank you for your help guys, much appreciated!

You are welcome. Now go and make us proud! ;D