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> doing the "draw at 2x scale and then scale down" dance that was popularized by OSX Originally OS X defaulted to drawing at 2x scale without any scaling down

• pedrocr 1y ago
  > Originally OS X defaulted to drawing at 2x scale without any scaling down because the hardware was designed to have the right number of pixels for 2x scale. That's an interesting related discussion. The idea that there is a physically correct 2x scale and fractional scaling is a tradeoff is not necessarily correct. First because different users will want to place the same monitor at different distances from their eyes, or have different eyesight, or a myriad other differences. So the ideal scaling factor for the same physical device depends on the user and the setup. But more importantly because having integer scaling be sharp and snapped to pixels and fractional scaling a tradeoff is mostly a software limitation. GUI toolkits can still place all ther UI at pixel boundaries even if you give them a target scaling of 1.785. They do need extra logic to do that and most can't. But in a weird twist of destiny the most used app these days is the browser and the rendering engines are designed to output at arbitrary factors natively and in most cases can't because the windowing system forces these extra transforms on them. 3D engines are another example, where they can output whatever arbitrary resolution is needed but aren't allowed to. Most games can probably get around that in some kind of fullscreen mode that bypasses the scaling. I think we've mostly ignored these issues because computers are so fast and monitors have gotten so high resolution that the significant performance penalty (2x easily) and introduced blurryness mostly goes unnoticed. > Take a look at this HiDPI rendering example in Leopard That's a really cool example, thanks. At one point Ubuntu's Unity had a fake fractional scaling slider that just used integer scaling plus font size changes for the intermediate levels. That mostly works very well from the point of view of the user. Because of the current limitations in Wayland I mostly do that still manually. It works great for single monitor and can work for multiple monitors if the scaling factors work out because the font scaling is universal and not per output.
  • sho_hn 1y ago
    What you want is exactly how fractional scaling works (on Wayland) in KDE Plasma and other well-behaved Wayland software: The scale factor can be something quirky like your 1.785, and the GUI code will generally make sure that things nevertheless snap to the pixel grid to avoid blurry results, as close to the requested scaling as possible. No "extra window system transforms".
    • pedrocr 1y ago
      That's what I referred to with "we'll be finally getting that in Wayland now". For many years the Wayland protocol could only communicate integer scale factors to clients. If you asked for 1.5 what the compositors did was ask all the clients to render at 2x at a suitably fake size and then scale that to the final output resolution. That's still mostly the case in what's shipping right now I believe. And even in integer scaling things like events are sent to clients in virtual coordinates instead of just going "here's your NxM buffer, all events are in those physical coordinates, all scaling is just metadata I give you to do whatever you want with". There were practical reasons to do that in the beginning for backwards compatibility but the actual direct scaling is having to be retrofitted now. I'll be really happy when I can just set 1.3 scaling in sway and have that just mean that sway tells Firefox that 1.3 is the scale factor and just gets back the final buffer that doesn't need any transformations. I haven't checked very recently but it wasn't possible not too long ago. If it is now I'll be a happy camper and need to upgrade some software versions.
      • zokier 1y ago
        > That's still mostly the case in what's shipping right now I believe All major compositors support fractional scaling extension these days which allows pixel perfect rendering afaik, and I believe Qt6 and GTK4 also support it. https://wayland.app/protocols/fractional-scale-v1#compositor-support https://wayland.app/protocols/fractional-scale-v1#compositor...
        • pedrocr 1y ago
• cosmic_cheese 1y ago
  Even today you run into the occasional foreign UI toolkit app that only renders at 1x and gets scaled up. We’re probably still years out from all desktop apps handling scaling correctly.
• frizlab 1y ago
  Completely unrelated but man was Aqua beautiful
• trinix912 1y ago
  Out of curiosity, do you happen to know why Apple thought that would be the cause for low adoption among 3rd party apps? Isn't scaling something that the OS should handle, that should be completely transparent, something that 3rd party devs can forget exists at all? Was it just that their particular implementation required apps to handle things manually?
  • kccqzy 1y ago
    I can only offer a hypothesis. Historically UI sizing was done in pixels, which means they are always integers. When developers support fractional scaling they can either update the app to do all calculations in floating point and store all intermediate results in floating point. That's hard. Or they could do calculations in floating point but round to integers eagerly. That results in inconsistent spacing and other layout bugs. With 2x scaling there only needs to be points and pixels which are both integers. Developers' existing code dealing with pixels can usually be reinterpreted to mean points, with only small changes needed to convert to and from pixels. With the 2x-and-scale-down approach the scaling is mostly done by the OS and using integer scaling makes this maximally transparent. The devs usually only need to supply higher resolution artwork for icons etc. This means developers only need to support 1x and 2x, not a continuum between 1.0 and 3.0.