Plugin: LayerComparer

[jacobwod]

Simple idea: let user select two layers in two dropdown menus and then easily control the opacity of those layers using a slider. Probably a good idea to place this in a central place in the UI, e.g. top or bottom, and hide entirely when plugin not active. Activation would be made by clicking a control button, next to zoom buttons.

Rough mockup:

[matself]

I see your point, Jacob. However, I think mixing two layers like that will be confusing. Your example shows orthophoto layers, and they can vary considerably in terms of brightness, contrast and saturation. If the aim is to be able to detect changes, it would be hard to quickly determine if a visible difference is an addition or a subtraction.
Instead, let me propose a curtain slider, like on http://kartbild.com. This tool has a similar selection process, i e you select one right hand side layer and one left hand side layer. The layers can be zoomed or panned under the slider, and the slider can me moved from side to side.

[jacobwod]

I agree @matself , that's a valid opinion. I have briefly considered the slider option previously but now I'm inclined to reconsider. By the way, great link!

Also, a third possibility would be transforming the mouse cursor to a "magnifying glass", and showing a different layer within the glass.

[persoderstrom]

Varberg has implemented something similar, https://karta.varberg.se/historiska-fonstret/. With magnifying glass, and more options in MENY.

[jacobwod]

That's right Per, but it's not a Hajk plugin unfortunately. But I'd be more than glad if someone would convert that solution to Hajk.

[jesade-vbg]

Varberg might make historiska-fönstret a plugin in the future, but probably not 2021 :/

[jacobwod]

OK folks, I took a look at it this afternoon and put together a quick proof-of-concept (using the Dummy plugin as UI container). I think it could work:

Hajk.Slider.First.Demo.mp4

[jacobwod]

Skarminspelning.2022-04-12.kl.12.27.03.mov

[jacobwod]

The final result:

With compare window visible:

[jacobwod]

I'm adding this small snackbar that provides an easy way to close the LayerComparer: