PIP window should show percentage during resize relative to the source display resolution

[waydabber]

Discussed in #1546

Could resizing a PIP window show a zoom percentage (in its title bar) during the drag? It's hard to know when it's back to normal.

[waydabber]

There should also be an option to easily set specific common sizes (25%, 50%, 75%, 100% etc) in relation to the streamed content's native resolution.

[vexir]

I would also include a way to set size as a custom value, and perhaps an option to set its size as a % of the main display's width or height. A good UI model for choosing between these three modes are two input boxes (one for W/H), three buttons or a dropdown for the three modes, and a checkbox or icon to maintain aspect ratio. The three modes being:

1. Set size as % of sub-display's resolution
2. Set size as % of main display's resolution
3. Set size as manually input value

I could also see a world in which setting a size in physical units would be useful for some applications, but that feels very niche and difficult to calculate/potentially error-prone.

[peterjcole]

+1, I was looking for this feature this week. As a start, being able to set it to 100% would be particularly useful.

My use case is that I want to start using BetterDisplay + PiP as a virtual second screen for occasional screen sharing in meetings, and not being able to scale to 100% is annoying because it means the picture is blurrier than it needs to be

I'd happily switch on an option forego the ability to resize the window at all and have it forced 100%, as I don't need to have this resized.

[waydabber]

All right, will implement it. :)

[waydabber]

Snap to significant sizes is a different feature, will be implemented in #3603

[waydabber]

The app now shows the percentage relative to the source in the middle of the PIP window during resize. With free aspect ratio it displays the percentage in an X%xY% format.