expose drag-and-drop clientX and clientY

joeyh commented 7 years ago

Available in all drag and drop events except for dragEnd.

sjakobi commented 5 years ago

This looks very reasonable to me. Can you give your approval, @HeinrichApfelmus?

sjakobi commented 5 years ago

CI may fail but this builds fine on my machine.

I think what's missing is that ClientXY should be exported?!

HeinrichApfelmus commented 5 years ago

Getting X and Y coordinates from a drag event seems useful.

However, there are two issues with this implementation:

It turns out that clientX/Y is relative to the top-left corner of the display in the browser, but this need not coincide with the top-left corner of the HTML page if the use has scrolled the page vertically! We use
```
var offset = $(this).offset();
var x      = e.pageX - offset.left;
```
for the mouse click events, but I do not know if we can obtain offset in the same way for drag events.
The use of read and toString() is unsatisfactory. We can marshal JSON values, so it would be more appropriate to express the argument to fun as a JSON value and read its fields on the Haskell side.

I'm happy to look into this if no one else calls dibs, but it may take another day or two.

HeinrichApfelmus / threepenny-gui