[Dropdown] module.is.onScreen returns wrong result when context is changed

[cubicle]

Have a look at this fiddle. The menu opens above the dropdown and not below as expected.

The reason is that module.is.onScreen uses $currentMenu.offset() for it's calculations. Unfortunately the returned coordinates are relative to the document and not relative to the supplied context.

I think you need to calculate the offset relative to the supplied context, like this:

            calculations = {
              context: {
                scrollTop : $context.scrollTop(),
                offset    : $context.offset(),
                height    : $context.outerHeight()
              },
              menu : {
                offset: $currentMenu.offset(),
                height: $currentMenu.outerHeight()
              }
            };
            onScreen = {
              above : (calculations.context.scrollTop) <= calculations.menu.offset.top - calculations.context.offset.top - calculations.menu.height,
              below : (calculations.context.scrollTop + calculations.context.height) >= calculations.menu.offset.top - calculations.context.offset.top + calculations.menu.height
            };

[awgv]

Hi @cubicle, thank you, but it seems to be a duplicate of #1340.

[cubicle]

Hi @Banandrew, im not sure about this. #1340 is marked as enhancement request and it's scope is not really clear to me. I'm not having a problem with the context's overflow property. Here is a fiddle without it. I would expect the menu to be opened below the dropdown.

The problem is the calculations doesn't respect the context's position at all.

[awgv]

@cubicle I apologize, you’re right.

[jlukic]

The openLeftward function had the same issue with not correctly calculating context offset.

Example here
http://jsfiddle.net/ogrdhaf0/

I've added your fix @dannyBies and also fixed the leftward function