[EXTERNAL] Explanation of different scaling factors anywhere?

Mike Hearn mike at plan99.net
Thu Jan 30 16:29:08 UTC 2020

Yes, a scale transform doesn't affect layout. That's the issue. Browser
zoom scales fonts, images and widgets but in a way that affects layout
bounds, not only render bounds.

As far as I can tell there's no way to do a zoom or scale that affects
layout bounds with the public JavaFX API. Exploring why not and what could
work is how I ended up getting a bit lost in the weeds of all the different
scale factors. It *feels* like one of them should be applicable if only it
was public API. But I can't quite figure out which or how exactly it'd
work. If nobody else has ever examined this task (it seems not) then I
guess I can just compile my own JFX and experiment with forcing the
different factors and ratios to see what happens. I'm not sure the results
would be stable or portable though.

On Tue, Jan 28, 2020 at 11:09:04, Tom Schindl <tom.schindl at bestsolution.at>

> I think that can not work because layouts don't take the scale factor into
> account nor does stuff like ScrollView but i could be wrong.
> Tom
> On 27.01.20 17:29, David Grieve wrote:
> Wouldn't this just be a scale transform?
> -----Original Message-----
> From: openjfx-dev <openjfx-dev-bounces at openjdk.java.net> On Behalf Of
> Mike Hearn
> Sent: Monday, January 27, 2020 11:00 AM
> To: openjfx-dev at openjdk.java.net
> Subject: [EXTERNAL] Explanation of different scaling factors anywhere?
> Hello,
> A feature I often miss when using non-web GUIs is support for browser
> style zooming. In JavaFX it is quite easy to specify all font sizes in
> terms of "ems", relative sizes ("largest") or percentages and then adjust
> the base font size on a root node inside key handlers. This works OK but
> doesn't do much for images or other controls, and of course most JavaFX GUI
> code specifies sizes in terms of pixels.
> There are various scaling factors applied to pixel sizes. There is the
> per-node scaling transform, but this doesn't affect layout so isn't
> comparable to what browsers do. There's a per-screen DPI, there's a
> "platform scale", there's a
> "render scale" and then there's a "ui scale". These seem related to
> hidpi/retina support and are all internal (for the purposes of this
> question I'm happy to modify JavaFX itself).
> Render scale seems to affect resolution without affecting positions or
> layout, so that's not quite what I want. UI scale sounds promising but
> isn't documented and I couldn't quite figure it out by reading the code,
> though I could just fiddle with it and see what happens.
> It feels like someone probably explored this before now. Is there a way to
> effectively expand the size of every node without altering the size of the
> containing viewport, to get browser-style layout affecting zoom? If not,
> has anyone explored the complexity of the modifications required?
> thanks,
> -mike
> --
> Tom Schindl, CTO
> BestSolution.at <http://bestsolution.at/> EDV Systemhaus GmbH
> Salurnerstrasse 15. A-6020 Innsbruck
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