Add a 2D scale factor property

[Calinou]

This can be used to make 2D elements larger or smaller, independently of the current stretch mode.

Only the disabled and 2d stretch modes support this new property.

Note that I removed the property hint for shrink as it was causing the Project Settings GUI to recognize it as a string instead of a floating-point value (it seems there's no way to add property hints for floats).

Demo project

[akien-mga]

Moving to 3.2 milestone as we're about to enter the beta stage and release freeze for Godot 3.1. Only bug fixes against issues of the 3.1 milestone (or enhancements to core features of the 3.1 roadmap) will be considered until 3.1-stable is released.

Note: If it's merged after 3.1-stable is released, this change might be considered for cherry-picking into a later 3.1.x release.

[Calinou]

I rebased this pull request against the current master branch. Could this be reviewed? This would make it possible to support hiDPI easily in one of my projects 🙂

[akien-mga]

The added option seems interesting, but I'm wary of doing such changes to SceneTree so late in the release cycle, so I'd prefer to postpone for 4.0.

This can and should still be reviewed properly ASAP - and if it's deemed safe to include in 3.2, I don't mind changing the milestone back.

[aaronfranke]

@Calinou Any update? This needs a rebase. Additionally, it would be nice if a proposal was created for this for discussion.

[Calinou]

@aaronfranke 2d and viewport stretch modes are currently broken, so this can't be tested using the current master branch.

[aaronfranke]

@Calinou I just checked, in the latest master the viewport and canvas_items (2d?) stretch modes seem to be working. It's likely that this PR can be rebased now, unless there is something else missing in master.

[Calinou]

Superseded by #52170.