Cannot pinch to zoom on touch screens in graph view in GUI

[jfrost-mo]

Description

A common interaction pattern in touch interfaces is pinching to zoom. This does not work in the graph view of the cylc GUI.

Reproducible Example

1. Open a workflow in cylc GUI on a touch screen device, like a touchscreen laptop or a smartphone.
2. Open graph view.
3. Try to zoom via touch.

Expected Behaviour

Can zoom with touch controls, in a similar way to most other apps. Google maps is a good example of how this scrolling should work.

[oliver-sanders]

Hmmm.

I'm pretty sure I tried this out when the graph view was first added, but that was a while ago and we have no tests for touch screen gestures.

The pan/zoom functionality comes from an external library. If you get the chance, could you try these examples to see whether they work for you?

• http://bumbu.me/svg-pan-zoom/demo/inline.html
• http://bumbu.me/svg-pan-zoom/demo/mobile.html

[jfrost-mo]

Testing on a NIWA laptop (which are touchscreen!) the inline example doesn't work, the same as Cylc, while the mobile one does. This was tested in Chrome and Edge.

[oliver-sanders]

Great, thanks for checking. To close this, we can copy the event handling of the second example onto the graph view and see what we can do to test this in Cypress.

[oliver-sanders]

Attempt after #1810