Parts of these icons did not line up well with the pixel grid making them seem blurry or faded. This has been fixed.
You're right, but this makes it sharper at the default button+font size. Smaller sizes suffer, but larger sizes are OK for the most part. Considering how the lowest common display resolution right now is 1366x768 and the next most common display resolution is 1920x1080, I think that's a fair trade off. There aren't many people using 1280x720 or 1024x768 anymore. http://gs.statcounter.com/screen-resolution-stats/desktop/worldwide/
Ideally, it should be sharp at all sizes, but I don't know how to do that and our window buttons don't seem to be setup in a way that would allow that.
Just to be clear, I'm not against good defaults. I don't like that the defaults are adjusted in such way that icons look sharp only with one particular font size and one particular button size. After all, KDE Plasma is configurable. If we focus only on making defaults look good, then what's the point of making everything configurable?
I think the current solution is good enough.
In either case, my pov is probably way too personal so I won't block this change.
I think I agree that it's much better to improve things universally if we can. But if we can't, then improving things for the default settings is good too.
@ndavis, how well tested is this? We can't land this if it causes any regressions. I didn't spot any with a few font & size combinations but let's make sure we test extensively.
Also, I'd like some comments added to the code to indicate why we're using floating-point values for these.
It's not that well tested, but I've seen enough to know that this will still be a slight improvement for most users.
As I've said in a previous comment, smaller button/font size combinations suffer. I justified it by saying that resolutions below 1366x768 were rare these days. Larger button/font size combinations are OK because the lines get thicker, but with the git master version or with this patch, it won't be perfect.
I also said that the current approach does not allow much flexibility. One size does not fit all, so any change will improve some things and make other things worse. I chose to make the defaults better.
The easiest way to get sharp icons at all sizes would be to create multiple fixed sizes, but I don't know how to do that. Currently, an icon is defined at one size. I assume the button size settings scale things relative to the font size. For example, Very Large with 10pt Noto Sans is much larger than Very Large with 6pt Noto Sans.