Preserve ordering of annotations in the SVG? about annotorious

[kennysong]

Thanks for the quick reply! Your explanation of how the ordering algorithm works was quite helpful.

We found a workaround by re-ordering a selected annotation to the "top" of the SVG so the label is always visible (and reseting it to its original position when deselecting). This preserves clickability and readability in our use case.

[rsimon]

Hi!

Thanks! Yes, the shuffling is intentional - and I'm afraid there's no way to change it in Annotorious, except by forking it.

Annotorious sorts the shapes by size, and then stacks them so that the largest shape is at the bottom (added to the SVG first), and the smallest shape is at the top (added last). This way, no large shape will overlap a smaller shape, and all the shapes remain clickable.

If forking is an option for you, however: the change would be fairly minimal, I believe. Shouldn't take much more than commenting out this section in the annotation layer (or, alternatively, remove every call to redraw()).

The other alternative would be to switch to the OpenSeadragon version of Annotorious. This doesn't do any reshuffling, because it handles hit/hover detection in a different way (by querying a spatial index instead of relying on mouse events.)

Hope this helps!

[kennysong]

Hi @rsimon, quick follow-up question:

We switched to the OpenSeadragon version of Annotorious to be able to use zooming. You mentioned that

it handles hit/hover detection in a different way (by querying a spatial index instead of relying on mouse events.)

I just wanted to confirm that the order of .a9s-annotation elements in the SVG no longer affects hovering and clicking? This seems to be the behavior we observed during testing.

[rsimon]

Hi, yes that's right. The order of the SVG elements in the DOM is irrelevant to hit detection in the OSD version.

[kennysong]

Thanks for confirming! This is really useful, we no longer need to reset annotations "to its original position when deselecting" anymore.