Re: [csswg-drafts] [cssom-view] Add pageZoomFactor to window interface (#3538) from Mustaq Ahmed via GitHub on 2019-01-21 (public-css-archive@w3.org from January 2019)

From: Mustaq Ahmed via GitHub <sysbot+gh@w3.org>
Date: Mon, 21 Jan 2019 20:36:09 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-456192598-1548102968-sysbot+gh@w3.org>

Thanks for raising this, Ella.

To clarify, `pageZoomFactor` here means the ctrl+/- zoom in browser, as defined [here](https://drafts.csswg.org/cssom-view-1/#page-zoom), which is different from pinch zoom and device scale factor.  We have three related coordinate spaces here: physical pixels, device independent pixels (DIPs) and CSS pixels:
![image of proposed factor vs deviceScaleFactor](https://eirage.github.io/Conversion%20factors.png)

We already have [`window.devicePixelRatio`](https://drafts.csswg.org/cssom-view/#dom-window-devicepixelratio) to convert between physical and CSS pixels, but there is currently no way to convert any of these to DIPs or back.  The proposed `pageZoomFactor` fills the gap.


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Received on Monday, 21 January 2019 20:36:10 UTC