use precise coordinates for selections + use cosmetic pens

AA_UseHighDpiPixmaps is not related to previews, it's for icons on buttons.
devicePixelRatioF is needed to paint an image as is without highdpi scaling by Qt.

fix copyrights

polished

leave a single commit

rebase on D20841

revert

rebase on extracted HideRectItem

To paint non-pixelated icons on buttons.
This attribute "makes QIcon::pixmap() generate high-dpi pixmaps that can be larger than the requested size. Such pixmaps will have devicePixelRatio() set to a value higher than 1."

Qt supports a high DPI mode where the main coordinate system is virtualized and made independent of the display pixel density.
...
Geometry is now specified in device independent pixels. This includes widget and item geometry, event geometry, desktop, window and screen
geometry, and animation velocities. Rendered output is in device pixels, which corresponds to the display resolution. The ratio between the
device independent and device pixel coordinate systems is the devicePixelRatio.

Ideally, QWidget::mouseDoubleClickEvent() could be used instead of double tap gesture...
https://codereview.qt-project.org/#/c/259787/

removed needless image scaling

Beams look ugly when their width is >= 4 pixels.
The idea is to draw them with the same width regardless of DPI.
Another option is to not set Qt::FlatCap for thick pens, but I prefer this one.

use QPen::setWidthF() instead of QPen::setWidth()

reduced beam width

Hi, thanks for the review.
I know about the issues, I've uploaded the patch to avoid losing it :)

Well, actually, it was caught by @hetzenecker: https://phabricator.kde.org/D7581?id=22415#change-vIXPDUvyb3sZ

You are welcome!
I started to implement highdpi support from scratch, but then I found this change and it was a huge help!

ping

re-target to master

small fixes

fixed

Another approach: D20267

add a comment about turning off opacity effect

D9078 should fix thumbnails.

turn off opacity effect for highdpi with Qt < 5.12.4

Currently there is a bug in Qt which makes QGraphicsOpacityEffect not working: https://codereview.qt-project.org/#/c/257946/

rebase + refactoring

He also mentioned that those are minor issues that coulbe be fixed later.
This change is rather big and complicated, so it would be better to leave it with fixing one main issue on HiDPI displays.
@hetzenecker wrote: "Extracted QRect scaling to helper methods (there seems to be rounding errors now, those still have to be fixed)",
so I guess this is the only thing that needs to be checked for this patch.

Yes, I can do it. But what issues exactly?

I rebased and tested the patch on higdpi screen, it works.

Fix for tiny cards: D20061

done

This is strange. I can't reproduce it.
Could you provide more information?

• Wayland or X11
• version of Qt
• env | grep QT

+1 to adding gesture recognizers to KWidgetsAddons

D19122

ping

modify existing desktop file instead of installing a new one

I guess that there is a short period of time when UDisks daemon is in inconsistent state, i.e. org.freedesktop.UDisks2.Filesystem interface is removed for CD-ROM device, but the device's properties still have Optical=true.
Adding "updateBackend(udi);" before "emit deviceAdded(udi);" gives Udisks time to become consistent.

Wouldn't it be better to add mime types to org.kde.gwenview.desktop during the build?
https://lxr.kde.org/ doesn't respond, so I can't find an example for now.

Gwenview supports these formats only when it is built with KDcraw.
I used the approach from okular: when okular is built with support for a set of formats, then a separate desktop file is installed for them.
And the added gwenviewApplication_raw.desktop contains translations because it is just a modified copy of org.kde.gwenview.desktop.

ping

extend the comment

fix commit description