Selection region is off on integer scaling

[dmoebius]

Arch Linux, using Kooha 1.0.2, installed from AUR https://aur.archlinux.org/packages/kooha

I have a Hi-DPI screen with 3840x2160 pixels, 290 dpi. GNOME display scaled to 200%.

When I record a screen region, it seems that the real coordinates of the rectangle that defines the region are off by one half. Ie. when I define to record the region from (200,200) to (500,500), Kooha really records the region from (100,100) to (250,250).

[SeaDve]

Thanks for submitting the issue! Kooha uses a method in the dbus interface of gnome shell.
Try using the built-in screenshot tool (GNOME screenshot) if you can replicate the bug.

[dmoebius]

GNOME screenshot works fine; it records exactly the region I selected.

[SeaDve]

I'll investigate on it.

[dmoebius]

Just FYI, when I set GNOME's screen scale to 100% it records the correct region.

[SeaDve]

Not replicable on my end. I set up my display to be 175%, and it still records the correct area. It might be that you set it to 200%? I can't seem to find that option.

[HaasJona]

GNOME by default only allows scaling to integers, eg 100%, 200%, 300%, you might have experimental fractional scaling enabled or an experimental/hacked version installed. I could try replicatign with a stock Fedora install with 200% scaling later.

[SeaDve]

I cannot find the options for integer scaling, is it only available from hidpi's?

[HaasJona]

I can confirm this issue. I use 200% scaling and the recorded coordinates are all 200% too small.

[SeaDve]

Hi, I'm thinking of removing selection support, so I would like to know your opinions whether its the right choice. The reason is that it will be useless for most, since it would be possible now to select a specific monitor, or window to record.

[dodalovic]

For me, personally, it's an essential feature. This would force me to find another tool.

[dmoebius]

For me, it's an essential feature, too. I use this feature to crop off sensitive sections of my screen that I don't want to share in the recorded video.
I don't understand why you would remove such a useful feature. Besides the scaling issue it works very well.

[SeaDve]

I'm working on it, besides maintaining the feature, I'll support other desktop environments and fix this scaling issue. Check #73

[SeaDve]

I found the issue, it was that the original resolution should be divided by the actual resolutions of your screen then multiply back to x, y width and height

Kooha/src/backend/pipeline_builder.py

Line 66 in 39dc1e6

width = width * self.screen_width / 840

840 being the actual resolution, but haven't find a way for now how to get this value in GTK4

[SeaDve]

pushed the fix in development branch :D

Feel free to test it

[SeaDve]

fix merged to main branch

[dodalovic]

@SeaDve Is there any rough estimate of when the new release will be available? Thanks for the fix!!!!

[SeaDve]

Possibly after the release of GTK 4.3.3

Check #75 for the todo

[dmoebius]

Sorry for the late response (have been very busy). I verified that the fix works. Many thanks!! 😃 👍