[cssom-view] New feature - Zoom factor

[Demitrius]

Hello,

This is feature request for the zoom factor.

In some cases developers need to know current zoom factor. As usual, zoom can be set by hit Ctrl and + / Ctrl and - or from browser menu.

Where is no universal way in javascript to get the browser zoom factor Today.

First discussion #399

[cvrebert]

It's worth noting you appear to be referring to Page Zoom as opposed to Pinch Zoom. "Zoom" without further qualification is ambiguous.

[Demitrius]

Some clarification of requested value.

On desktop. Page default zoom = 100% If I type CTRL and + several times, zoom increase to 150% If I type CTRL and - several times, zoom decrease to 70%

I mean this zoom (requested value - 100, 150, 70)

On mobile. When user drag the fingers to pan across the screen and zoom in / out page, requested value must updating. In case when site scale down to fit the screen, requested value must be less than 100%

[staktrace]

The "pinch zoom" (mobile finger-dragging) will be exposed by the proposed visual viewport API: https://github.com/WICG/ViewportAPI, perhaps it's worth making the "page zoom" also be exposed as a property on that object?

[Demitrius]

Yes, would be nice expose 'visualViewport.scale' as a property.

This is the same scale as used in the viewport tag.

[Demitrius]

Hi guys!

What's about this issue?

[hexalys]

@staktrace

visualViewport being an event object, I don't think it is well suited for "page zoom". Unlike mobile, where pinch-zoom start at 1.0; page-zoom can be anything right from the start and should be detectable on initial load. I preferably would like to see that page-zoom scale property on a prospect layout viewport object exposed on the window object.