Support overriding screen dimensions

[lutien]

To support emulation of mobile devices, the clients should be able to emulate screen.width/screen.heights properties. CDP also supports it via Emulation.setDeviceMetricsOverride.
The question is here what would be the best interface. I see a few options:

• the viewport settings set via browsingContext.setViewport command should automatically apply to screen dimensions;
• browsingContext.setViewport command has a new argument/s to set the screen dimensions independently of viewport;
• we have a new command to just set the screen settings.

[OrKoN]

There is also a draft spec for screen/window management https://www.w3.org/TR/window-management/

[sadym-chromium]

I filed a feature request for Window Management specification: w3c/window-management#151

[css-meeting-bot]

The Browser Testing and Tools Working Group just discussed Support overriding screen dimensions.

The full IRC log of that discussion

<tidoust> Topic: Support overriding screen dimensions
<tidoust> github: https://github.com//issues/981
<tidoust> sasha: We support overriding the viewport but it does not affect the screen size, which would be useful for clients and end users.
<tidoust> ... You cannot do it with BiDi yet.
<sadym> q+
<tidoust> ... Should we add this? Automatically applied when we set the viewport? Another argument? Completely separate command?
<jgraham> ack next
<tidoust> sadym: The Window Management API spec provides not only the screen dimensions but also additional information that would be useful to use.
<jgraham> q+
<tidoust> ... It would be nice to collaborate with them on the emulation and specification. That would be useful for WPT as they currently have manual tests.
<jgraham> ack next
<sasha> q+
<tidoust> jgraham: It makes sense for me to have a completely different command here. Or for it to be different arguments to the command rather than repurposing the argument of the comment.
<sadym> q+
<tidoust> s/comment/command
<orkon> q+
<jgraham> ack next
<tidoust> sasha: If there's potential to have more arguments, it makes sense to have a different command.
<jgraham> ack next
<tidoust> ... To cover different screen settings
<tidoust> sadym: It sounds like it falls perfectly under emulation.
<jgraham> ack next
<jgraham> q+
<tidoust> orkon: I looked at the spec. I think that's cool. Screens have their own pixel ratio, additionally. It may make sense to revise devicePixelRatio for the screen specifically.
<jgraham> ack next
<tidoust> jgraham: To what extent it makes sense to do that across browsing contexts or user contexts. Different values may not make sense.
<tidoust> ... I'm not sure. Maybe you can argue that you can have browsing contexts on different physical screens.