Add zoom factor

[niutech]

I've added the zoom factor (50%-300%) in the Webpage settings.

This branch is based on the Release 2.6.0-beta, for changes see the last commit.

[alexk111]

It looks like the zoom-factor branch was created from the Release 2.6.0 branch instead of master. This will merge all of the Rel 2.6.0 changes with the zoom-factor ones.
This also makes it impossible to see the code changes made for that specific feature.

[niutech]

@alexk111 Done!

[alexk111]

Thanks for the update!
The proposed solution will only allow setting the zoom level if all webview instances open a url on different domains. If multiply webviews will try to open a same-domain url there will be a random zoom level applied by a last webview setting the zoom factor for the domain.

You may reproduce the problem by copy-pasting a webpage widget instance and setting different zoom factors for them.

Quote from https://www.electronjs.org/docs/latest/api/webview-tag

The zoom policy at the Chromium level is same-origin, meaning that the zoom level for a specific domain propagates across all instances of windows with the same domain. Differentiating the window URLs will make zoom work per-window.

[niutech]

True, but this could be worked around by setting custom CSS per webview: html { zoom: 80%; }

[alexk111]

Yup, had the same idea :) Will try it a bit later.
Also researched how this is implemented in the zoom extensions for Chrome - not helped much though, as they are using the zoom feature of the Chrome-specific chrome.tabs API.

[alexk111]

Experimented with the CSS zoom property. It scales elements and triggers layout recalculations, but does not scale the viewport. As a result, @media queries do not respond as expected, since the document's viewport dimensions remain unchanged.

[niutech]

@alexk111 So what do you propose? Maybe, to keep it simple, just store a hash table of zoom per domain in the store: zoom['example.org'] = 0.8?

[alexk111]

Since applying a zoom factor on a per-widget basis isn't possible, and its state is managed by Chromium, I implemented it as a context menu action rather than a widget setting. The change has already been merged into master.

[niutech]

Thanks!