7 ms·

My kingdom for Wayland fractional scaling that doesn’t make my apps blurry. It makes the feature a complete nonstarter for me.

by jckahn 3y ago

enriquto 3y ago
Fractional scaling, by definition, will make stuff blurry. Clean bitmap graphics and fractional scaling are incompatible requirements. Proof: consider a pattern of alternating black and white pixels: 0, 255, 0, 255, 0, 255, etc. This pattern cannot be scaled to a non-integer factor without introducing gray colors (i.e., by blurring-out the pattern). If your app produces this pattern, then fractional scaling will blur your app.
- throwaway11205 3y ago
  Fractional scaling works perfectly well on Xorg Linux and Windows, but looks blurry on Wayland Linux. Maybe it's not micrometer-scale crisp, but I can't see that. Text on Wayland is very visibly blurred. And it's not just text, but UI controls too. It looks like Wayland just renders the lower integer scale factor and then stretches the resulting bitmap image. That's bullshit.
  - jsheard 3y ago
    Doesn't macOS do it the other way, rendering at the next highest integer scale factor and then downscaling to fit the display? If you can't render fractional factors natively for tech debt reasons then that's the least bad way to do it.
    - throwaway11205 3y ago
      MacOS way is better, text is blurry, but much less. I still don't like it though, but can use it in an emergency. But there apparently is another way that Xorg and Windows uses. I have perfectly crisp (as far as my eyes can tell) UI and text on both systems at 150% scale (27" 4K display). > for tech debt reasons I thought Wayland was supposed to fix the tech debt - so now it introduced some that makes bare basic features impossible?
    - DiabloD3 3y ago
      It does for any app that can't scale; all modern OSX apps can scale natively. I've been using that trick for integer-like scaling for years to deal with fractional scaling while preserving the quasi-aliasing ("crispness") of the source image. However, Wayland does not prescribe any method for non-integer scaling. Any Wayland WM could choose to do the same thing, and it would be hardware accelerated essentially for free. Both X11 and Wayland WMs typically don't use this trick, and neither does Windows.
  - jorvi 3y ago
    It is exactly (some) Xorg apps that render blurry on Wayland. You are blaming the wrong party for “bullshit”. Xorg scaling sucks, whereas Wayland’s is great.
  - darthrupert 3y ago
    I have the exact opposite experience: fonts are crisp on Wayland and blurry crap on xorg.
- jackdaniel 3y ago
  Not everything is a bitmap. Ordinary drawing operations operate on coordinates, so fractional scaling should not lead to any blur (although may miss some pixel-perfect designs). In other words vectors may be scaled with little precision loss, or they may be scaled naively (render to bitmap and then scale the bitmap).
  - seabrookmx 3y ago
    This. People seem to forget that you can zoom to 125% in your browser without blur, since the UI elements on the web are vector-based.
    - enriquto 3y ago
      There's nothing special about the browser. Bitmap images are blurred by fractional scaling. That is inevitable.
      - seabrookmx 3y ago
        Yes but the fonts, boxes and lines are all fine. And on the web the image issue is usually resolved by starting hi res to begin with and sampling down not up. When people complain about desktop apps not scaling they aren't complaining about the odd icon, it's the whole app looking like a smeary mess because it's not using vector based graphics. Fronts, grid lines etc. become blurry.
  - pxc 3y ago
    Is this how DPI scaling in X11 works? Also, don't you get the same effect (readable large fonts but alignment changes a bit) when you increase the size of your UI fonts, even without changing overall UI scaling? Why are people (apparently) so attached to pixel alignments for OS-native GUIs?
- mahkoh 3y ago
  That is not the case on wayland. Wayland applications with support for the fractional scaling protocol can render without any blur at any fractional scale. This is because the protocol negotiates the size of the underlying buffer. If the client and the compositor agree on the scale, then no scaling of the buffer will happen in the compositor because the client has attached a buffer that is the exact pixel size size of the window on the physical display. It is up to the client how it implements the case you described. E.g. it could alternate between 1 black and 1 white pixel in the physical buffer or it could sometimes make two adjacent pixels the same color. Source: I was involved in the design of this protocol and we had example clients that used this exact pattern. Chromium also supports this protocol without any blur.
  - llm_trw 3y ago
    > E.g. it could alternate between 1 black and 1 white pixel in the physical buffer or it could sometimes make two adjacent pixels the same color. This is a very odd definition of "no blur".
    - mahkoh 3y ago
      It works in chromium without anything I'd call blur. Here it is at 175% scale: https://i.ibb.co/DtKm69d/image.png https://i.ibb.co/DtKm69d/image.png
      - enriquto 3y ago
        Does the scaling change the kerning of the letters? This looks horrific! (and, yes, blurry, or "antialiased" as is custom to name it).
        mahkoh 3y ago
        No, that's just the font I'm using. It's the same if I keep the scale at 1 and then zoom in the browser.
        3y ago
- DiabloD3 3y ago
  I don't know why this guy is being downvoted, he is correct. You cannot scale things to non-integer amounts without incurring some damage. Blurry/fuzzyness, ringing, screen door effect, etc, you cannot avoid these no matter how smart your scaling algorithm is as long as you're upscaling it to something inbetween 100% and 200%. Nyquist-Shannon is a bitch. Wayland made a decision way back that non-scaling apps can only be integer scaled to avoid this defect. This was the correct decision, objectively. Unfortunately, people still choose to own monitors that have weird resolutions that do not approximate 96dpi after integer scaling. Thankfully, 200% dpi screens (ex: 3840x2160 in 24", where 24" are normally 1080p) are starting to become the norm, so someday this problem will go away: you will always be scaling at least 200%, making non-integer scaling artifacts a lot less visible. Also, I think the parent comment that enriquto replied to might be confused and is merely asking for nearest neighbor scaling. This is not part of Wayland (which is just a protocol), and is managed entirely by the WM being used. Given Wayland is trying to enforce integer scaling, WMs allowing choosing nearest neighbor when integer scaling would be preferable in many cases.
  - jwells89 3y ago
    > Unfortunately, people still choose to own monitors that have weird resolutions that do not approximate 96dpi after integer scaling. It’s not always a choice unfortunately. I buy displays that are capable of a clean 1x or 2x when I can, but there’s a ton of laptops that still need fractional scaling. Take my Thinkpad X1 Nano. Great laptop in a lot of ways, including the screen (~500 nits brightness, excellent backlight consistency, color, and contrast, no glare) except that it runs at a resolution that requires 1.5x scaling to be usable. Looking at replacement candidate laptops, the only ones that have 2x screens that aren’t a downgrade somehow destroy battery life (e.g. 3000x2000 OLED panel in Dragonfly Elite G4, which docks 3-4h of battery). 1x screens in this category for some reason are all kinda crappy with e.g. dim 350 nit backlights that start to struggle in a moderately naturally well-lit room, which is just goofy in a portable machine that’s likely to get usage in a bright environment. This is one thing that MacBooks objectively do consistently better.
    - goosedragons 3y ago
binkHN 3y ago
I think KDE6, which is just around the corner, is going to be your best bet. That said, some older programs still require xwayland and you will not get too far with these.
jacek 3y ago
I use KDE Plasma 5.27 (6 with many improvements is around the corner) on Wayland and fractional scaling is handled very well, nothing is blurry, no hacks required. If KDE recognizes an app that is not Wayland compatible (like most Electron apps), it will just run it in X11 mode (there's a setting for that, enabled by default). See the screenshot of my settings: https://imgur.com/a/VQHD5vT https://imgur.com/a/VQHD5vT
- jckahn 3y ago
  I’ve heard that the situation is better on KDE, but for better or worse I’m a GNOME user. I probably should have specified that!
  - hollerith 3y ago
    I'm using Wayland and Gnome set to a fractional scaling factor to write this, and none of the apps I use regularly are blurry although I have to pass command-line arguments to Chrome and had to compile Emacs from source code to achieve that. In fact, none of them were blurry 3 years ago.
phkahler 3y ago
>> My kingdom for Wayland fractional scaling that doesn’t make my apps blurry. I'm convinced I don't understand this thing. I feel like it's NOT the compositors job to scale the pixels of an application. That might be a good hack for super high resolution screens with applications that don't know how to handle high DPI but it's an inferior solution. Scaling text at the pixel level is going to be inferior to rendering it at higher resolution to start with. So how does it work? Do we have per-monitor setting for scale factor, and both the DE and the apps need to follow it for idea behavior? And the compositor scaling the apps is a stopgap? Is that it, or is there more to this?
- alwayslikethis 3y ago
  Let me type down what I learned through many hours of research. Under a Wayland compositor, there are basically three types of apps. 1. XWayland apps which cannot use Wayland's scaling protocols, but may be able to use Xft.dpi to scale themselves. Examples include Electron apps when not running on Wayland and later versions of Qt5. These will work without blurriness but they cannot support proper multi-dpi support. The Wayland compositor has no way of detecting whether it actually scales. Some compositors (KDE, Hyprland) let you not scale them, but others (GNOME) will make them super blurry because they are rendered at 96 DPI and stretched to the needed scale. GTK3 notably never supported fractional scaling on X11. 2. Wayland apps which supports integer scaling only. Examples include GTK3, GTK4, Qt5 apps, Mozilla Firefox (minus the experimental fractional scaling feature, which is very buggy). When compositor wants to render at a fractional resolution, the app will render at the nearest integer scale, and the compositor will downsample it. These don't look ideal, but aren't super blurry either, and will work properly with multi-dpi monitors. 3. Wayland apps which properly support fractional scaling via wp-fractional-scale-v1. This is a recent addition to the protocol, so not widely supported yet. The only toolkit that supports it is Qt6, but Chromium (incl. recent Electron apps in Wayland mode) also supports it. Some terminal emulators do too. This results in pixel perfect rendering and looks ideal and works properly with multi-dpi monitors. Downsampling works well on Macs which have high resolution screens such that you mostly use at least 175% scaling. At lower scales such as 125% (e.g. 1080p 13-14 inch laptops) and 150% (e.g. 1440p 14-16 inch devices), the degradation is fairly obvious if you use smaller fonts. This also breaks subpixel rendering (Macs haven't had it for a long time), which is important for making fonts look good on lower DPI screens. In some ways, Wayland scaling is a regression for KDE because Qt5 had proper fractional scaling for some time under X11, which was not implemented in Wayland as the protocol came out after Qt5 lost support.
pxc 3y ago
If you've got a whole kingdom on offer, you can bite the bullet and buy monitors that all have the same DPI. It's painful, but it's what I've done.
- jckahn 3y ago
  Not for my Framework 13 laptop. There’s only one screen resolution option. Even when I don’t have it plugged into my 4K external monitor, Wayland’s fractional scaling looks atrocious on Ubuntu 22.04.
k8svet 3y ago
I've never ever noticed blurriness from downscaled integer up-scaled Wayland apps. Blurriness is almost always due to use of xwayland. These are completely unrelated technically.

My kingdom for Wayland fractional scaling that doesn’t make my apps blurry. It makes the feature a complete nonstarter for me.

by jckahn 3y ago

My kingdom for Wayland fractional scaling that doesn’t make my apps blurry. It makes the feature a complete nonstarter for me.

enriquto 3y ago

Fractional scaling, by definition, will make stuff blurry. Clean bitmap graphics and fractional scaling are incompatible requirements. Proof: consider a pattern of alternating black and white pixels: 0, 255, 0, 255, 0, 255, etc. This pattern cannot be scaled to a non-integer factor without introducing gray colors (i.e., by blurring-out the pattern). If your app produces this pattern, then fractional scaling will blur your app.

throwaway11205 3y ago
Fractional scaling works perfectly well on Xorg Linux and Windows, but looks blurry on Wayland Linux. Maybe it's not micrometer-scale crisp, but I can't see that. Text on Wayland is very visibly blurred. And it's not just text, but UI controls too. It looks like Wayland just renders the lower integer scale factor and then stretches the resulting bitmap image. That's bullshit.
- jsheard 3y ago
  Doesn't macOS do it the other way, rendering at the next highest integer scale factor and then downscaling to fit the display? If you can't render fractional factors natively for tech debt reasons then that's the least bad way to do it.
  - throwaway11205 3y ago
    MacOS way is better, text is blurry, but much less. I still don't like it though, but can use it in an emergency. But there apparently is another way that Xorg and Windows uses. I have perfectly crisp (as far as my eyes can tell) UI and text on both systems at 150% scale (27" 4K display). > for tech debt reasons I thought Wayland was supposed to fix the tech debt - so now it introduced some that makes bare basic features impossible?
  - DiabloD3 3y ago
    It does for any app that can't scale; all modern OSX apps can scale natively. I've been using that trick for integer-like scaling for years to deal with fractional scaling while preserving the quasi-aliasing ("crispness") of the source image. However, Wayland does not prescribe any method for non-integer scaling. Any Wayland WM could choose to do the same thing, and it would be hardware accelerated essentially for free. Both X11 and Wayland WMs typically don't use this trick, and neither does Windows.
- jorvi 3y ago
  It is exactly (some) Xorg apps that render blurry on Wayland. You are blaming the wrong party for “bullshit”. Xorg scaling sucks, whereas Wayland’s is great.
- darthrupert 3y ago
  I have the exact opposite experience: fonts are crisp on Wayland and blurry crap on xorg.
jackdaniel 3y ago
Not everything is a bitmap. Ordinary drawing operations operate on coordinates, so fractional scaling should not lead to any blur (although may miss some pixel-perfect designs). In other words vectors may be scaled with little precision loss, or they may be scaled naively (render to bitmap and then scale the bitmap).
- seabrookmx 3y ago
  This. People seem to forget that you can zoom to 125% in your browser without blur, since the UI elements on the web are vector-based.
  - enriquto 3y ago
    There's nothing special about the browser. Bitmap images are blurred by fractional scaling. That is inevitable.
    - seabrookmx 3y ago
      Yes but the fonts, boxes and lines are all fine. And on the web the image issue is usually resolved by starting hi res to begin with and sampling down not up. When people complain about desktop apps not scaling they aren't complaining about the odd icon, it's the whole app looking like a smeary mess because it's not using vector based graphics. Fronts, grid lines etc. become blurry.
- pxc 3y ago
  Is this how DPI scaling in X11 works? Also, don't you get the same effect (readable large fonts but alignment changes a bit) when you increase the size of your UI fonts, even without changing overall UI scaling? Why are people (apparently) so attached to pixel alignments for OS-native GUIs?
mahkoh 3y ago
That is not the case on wayland. Wayland applications with support for the fractional scaling protocol can render without any blur at any fractional scale. This is because the protocol negotiates the size of the underlying buffer. If the client and the compositor agree on the scale, then no scaling of the buffer will happen in the compositor because the client has attached a buffer that is the exact pixel size size of the window on the physical display. It is up to the client how it implements the case you described. E.g. it could alternate between 1 black and 1 white pixel in the physical buffer or it could sometimes make two adjacent pixels the same color. Source: I was involved in the design of this protocol and we had example clients that used this exact pattern. Chromium also supports this protocol without any blur.
- llm_trw 3y ago
  > E.g. it could alternate between 1 black and 1 white pixel in the physical buffer or it could sometimes make two adjacent pixels the same color. This is a very odd definition of "no blur".
  - mahkoh 3y ago
    It works in chromium without anything I'd call blur. Here it is at 175% scale: https://i.ibb.co/DtKm69d/image.png https://i.ibb.co/DtKm69d/image.png
    - enriquto 3y ago
      Does the scaling change the kerning of the letters? This looks horrific! (and, yes, blurry, or "antialiased" as is custom to name it).
      - mahkoh 3y ago
        No, that's just the font I'm using. It's the same if I keep the scale at 1 and then zoom in the browser.
        3y ago
DiabloD3 3y ago
I don't know why this guy is being downvoted, he is correct. You cannot scale things to non-integer amounts without incurring some damage. Blurry/fuzzyness, ringing, screen door effect, etc, you cannot avoid these no matter how smart your scaling algorithm is as long as you're upscaling it to something inbetween 100% and 200%. Nyquist-Shannon is a bitch. Wayland made a decision way back that non-scaling apps can only be integer scaled to avoid this defect. This was the correct decision, objectively. Unfortunately, people still choose to own monitors that have weird resolutions that do not approximate 96dpi after integer scaling. Thankfully, 200% dpi screens (ex: 3840x2160 in 24", where 24" are normally 1080p) are starting to become the norm, so someday this problem will go away: you will always be scaling at least 200%, making non-integer scaling artifacts a lot less visible. Also, I think the parent comment that enriquto replied to might be confused and is merely asking for nearest neighbor scaling. This is not part of Wayland (which is just a protocol), and is managed entirely by the WM being used. Given Wayland is trying to enforce integer scaling, WMs allowing choosing nearest neighbor when integer scaling would be preferable in many cases.
- jwells89 3y ago
  > Unfortunately, people still choose to own monitors that have weird resolutions that do not approximate 96dpi after integer scaling. It’s not always a choice unfortunately. I buy displays that are capable of a clean 1x or 2x when I can, but there’s a ton of laptops that still need fractional scaling. Take my Thinkpad X1 Nano. Great laptop in a lot of ways, including the screen (~500 nits brightness, excellent backlight consistency, color, and contrast, no glare) except that it runs at a resolution that requires 1.5x scaling to be usable. Looking at replacement candidate laptops, the only ones that have 2x screens that aren’t a downgrade somehow destroy battery life (e.g. 3000x2000 OLED panel in Dragonfly Elite G4, which docks 3-4h of battery). 1x screens in this category for some reason are all kinda crappy with e.g. dim 350 nit backlights that start to struggle in a moderately naturally well-lit room, which is just goofy in a portable machine that’s likely to get usage in a bright environment. This is one thing that MacBooks objectively do consistently better.
  - goosedragons 3y ago

binkHN 3y ago

I think KDE6, which is just around the corner, is going to be your best bet. That said, some older programs still require xwayland and you will not get too far with these.

jacek 3y ago

I use KDE Plasma 5.27 (6 with many improvements is around the corner) on Wayland and fractional scaling is handled very well, nothing is blurry, no hacks required. If KDE recognizes an app that is not Wayland compatible (like most Electron apps), it will just run it in X11 mode (there's a setting for that, enabled by default). See the screenshot of my settings: https://imgur.com/a/VQHD5vT https://imgur.com/a/VQHD5vT

jckahn 3y ago
I’ve heard that the situation is better on KDE, but for better or worse I’m a GNOME user. I probably should have specified that!
- hollerith 3y ago
  I'm using Wayland and Gnome set to a fractional scaling factor to write this, and none of the apps I use regularly are blurry although I have to pass command-line arguments to Chrome and had to compile Emacs from source code to achieve that. In fact, none of them were blurry 3 years ago.

phkahler 3y ago

>> My kingdom for Wayland fractional scaling that doesn’t make my apps blurry. I'm convinced I don't understand this thing. I feel like it's NOT the compositors job to scale the pixels of an application. That might be a good hack for super high resolution screens with applications that don't know how to handle high DPI but it's an inferior solution. Scaling text at the pixel level is going to be inferior to rendering it at higher resolution to start with. So how does it work? Do we have per-monitor setting for scale factor, and both the DE and the apps need to follow it for idea behavior? And the compositor scaling the apps is a stopgap? Is that it, or is there more to this?

alwayslikethis 3y ago
Let me type down what I learned through many hours of research. Under a Wayland compositor, there are basically three types of apps. 1. XWayland apps which cannot use Wayland's scaling protocols, but may be able to use Xft.dpi to scale themselves. Examples include Electron apps when not running on Wayland and later versions of Qt5. These will work without blurriness but they cannot support proper multi-dpi support. The Wayland compositor has no way of detecting whether it actually scales. Some compositors (KDE, Hyprland) let you not scale them, but others (GNOME) will make them super blurry because they are rendered at 96 DPI and stretched to the needed scale. GTK3 notably never supported fractional scaling on X11. 2. Wayland apps which supports integer scaling only. Examples include GTK3, GTK4, Qt5 apps, Mozilla Firefox (minus the experimental fractional scaling feature, which is very buggy). When compositor wants to render at a fractional resolution, the app will render at the nearest integer scale, and the compositor will downsample it. These don't look ideal, but aren't super blurry either, and will work properly with multi-dpi monitors. 3. Wayland apps which properly support fractional scaling via wp-fractional-scale-v1. This is a recent addition to the protocol, so not widely supported yet. The only toolkit that supports it is Qt6, but Chromium (incl. recent Electron apps in Wayland mode) also supports it. Some terminal emulators do too. This results in pixel perfect rendering and looks ideal and works properly with multi-dpi monitors. Downsampling works well on Macs which have high resolution screens such that you mostly use at least 175% scaling. At lower scales such as 125% (e.g. 1080p 13-14 inch laptops) and 150% (e.g. 1440p 14-16 inch devices), the degradation is fairly obvious if you use smaller fonts. This also breaks subpixel rendering (Macs haven't had it for a long time), which is important for making fonts look good on lower DPI screens. In some ways, Wayland scaling is a regression for KDE because Qt5 had proper fractional scaling for some time under X11, which was not implemented in Wayland as the protocol came out after Qt5 lost support.

pxc 3y ago

If you've got a whole kingdom on offer, you can bite the bullet and buy monitors that all have the same DPI. It's painful, but it's what I've done.

jckahn 3y ago
Not for my Framework 13 laptop. There’s only one screen resolution option. Even when I don’t have it plugged into my 4K external monitor, Wayland’s fractional scaling looks atrocious on Ubuntu 22.04.

k8svet 3y ago

I've never ever noticed blurriness from downscaled integer up-scaled Wayland apps. Blurriness is almost always due to use of xwayland. These are completely unrelated technically.