Overlays don't get horizontally fliped when the image it's flipped

[Zardoz89]

So, you open an image with an overlay that draws a rectangle over it. If using the OSD intrface, an user flips horizontally the image, the overlay don't get flipped. At least, it's strange, specially when it works correctly using the rotation buttons. Here is a example :

Original image + overlay :

Flipped image + overlay :

[iangilman]

Indeed, this is a known issue: #1614

Evidently no one has decided to take it on. Let me know if you are interested in working on it and I can point you in the right direction.

[BeebBenjamin]

I need this fixed at some point too. I can attempt to fix it under guidance.

[Zardoz89]

Also, I could try to help with it.

[iangilman]

@BeebBenjamin @Zardoz89 Fantastic! Presumably the fix will go into this function:

openseadragon/src/overlay.js

Line 296 in 6abcc76

_getOverlayPositionAndSize: function(viewport) {

You can probably get some inspiration from the rotation handling.

I expect the typical user will want the overlay position flipped but not the actual overlay contents flipped (i.e. they wouldn't want the overlay text to be backwards). Though I could see an argument for the other way. What do you think?

I'll leave it to you to figure out who is taking the lead on this.