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Wayland does have some ways (meaning protocols) to do explicit positioning, e.g. relative to a parent owned by the same client (for popups), that have been stan

by sho_hn 6y ago

Wayland does have some ways (meaning protocols) to do explicit positioning, e.g. relative to a parent owned by the same client (for popups), that have been standardized. The primary limitation is not to allow clients to set their x,y in the global scene (or even look them up), but there are proposed protocols that allow global positioning in a semantic sense like "I would like to be at the left edge" or "I am an overlay type thing" (z positioning). Some of those are in production use internally to Wayland-based desktop shells, e.g. KDE's Plasma, or used in communities like sway/wlroots+addons (e.g. dmenu implementations). Why not do x,y? It means you don't have this sort of level positioning code in the apps, which are very expensive or impossible to fix after the fact (apps stop being maintained, etc.) when new ideas come up. Say you want to apply a transform to client windows - scale them, or put them into a 3D sphere in a HMD. Wayland compositors have full flexibility there because the apps don't make assumptions.

saagarjha 6y ago
> Say you want to apply a transform to client windows - scale them, or put them into a 3D sphere in a HMD. Wayland compositors have full flexibility there because the apps don't make assumptions. Except that macOS can do all this regardless? WindowServer can do all sorts of transformations on windows, fully independent of the position the window has set for itself. That's how all the fancy Mission Control/Exposé animations work.
- vetinari 6y ago
  With wayland, you can do this and the apps won't notice because of the limits placed upon them earlier: https://www.youtube.com/watch?v=_FjuPn7MXMs https://www.youtube.com/watch?v=_FjuPn7MXMs Can macOS do it? The point of this demo is not practical usability today, but to demonstrate, that global positioning on the desktop as we know today might get much more complex in future. So why shut the door?
  - saagarjha 6y ago
    macOS can place windows wherever it likes, see Mission Control. It has APIs that can literally reach across processes so you can draw a window’s content as a little “view” in your window if you like, and apply the rich set of CoreAnimation transformations to it. What happens in a case like that is that the window gets placed in a new coordinate system that is orthogonal to its “original coordinates” (since of course it has no idea what would be going on without changes to the application frameworks) and moved and rendered freely. (Again, Mission Control was added with zero work or cooperation on the part of applications, even though they had the “window move” APIs from day one, which was many years prior. I would be entirely unsurprised if one could make a demo like the one you just showed fairly “easily”, barring private APIs and accessibility permissions and such.)
    - vetinari 6y ago
      Interesting, thank you.

by sho_hn 6y ago

saagarjha 6y ago

> Say you want to apply a transform to client windows - scale them, or put them into a 3D sphere in a HMD. Wayland compositors have full flexibility there because the apps don't make assumptions. Except that macOS can do all this regardless? WindowServer can do all sorts of transformations on windows, fully independent of the position the window has set for itself. That's how all the fancy Mission Control/Exposé animations work.

vetinari 6y ago
With wayland, you can do this and the apps won't notice because of the limits placed upon them earlier: https://www.youtube.com/watch?v=_FjuPn7MXMs https://www.youtube.com/watch?v=_FjuPn7MXMs Can macOS do it? The point of this demo is not practical usability today, but to demonstrate, that global positioning on the desktop as we know today might get much more complex in future. So why shut the door?
- saagarjha 6y ago
  macOS can place windows wherever it likes, see Mission Control. It has APIs that can literally reach across processes so you can draw a window’s content as a little “view” in your window if you like, and apply the rich set of CoreAnimation transformations to it. What happens in a case like that is that the window gets placed in a new coordinate system that is orthogonal to its “original coordinates” (since of course it has no idea what would be going on without changes to the application frameworks) and moved and rendered freely. (Again, Mission Control was added with zero work or cooperation on the part of applications, even though they had the “window move” APIs from day one, which was many years prior. I would be entirely unsurprised if one could make a demo like the one you just showed fairly “easily”, barring private APIs and accessibility permissions and such.)
  - vetinari 6y ago
    Interesting, thank you.