Drag and drop issue in Chrome related to Windows scale (125%)

user_4350476 0
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I have an issue with drag and drop on Chrome (v69.0.3497.100). Specifically, some of the drag and drop events are getting fired when Windows scaling is other than 100% even though they shouldn't be firing.

Check out stackblitz example, and try to drag "blue" rectangle over itself (just drag, move a little bit downwards and drop). If Windows scaling is set to 100% (browser zoom is 100% as well) then one event is fired (dragEnter) as expected (check the console). But, if Windows scaling is set to 125% (but browser zoom is still 100%) then three events are fired (two dragEnter and one dragLeave), and I expected only one event to be fired since the element was dragged and dropped on itself (as it was the case with 100% scale level).

It could be that since this is Windows zoom (and not browser's zoom) the left ("lightred") rectangle is larger that it appears, and it goes below right rectangle, and events are propagated to it, although I couldn't prove that since all elements have correct size in the inspector.

This doesn't seem to be happening in latest Firefox, IE or Edge.

Does anyone know why is this happening and how to fix it?

drag-and-drop google-chrome html javascript
2 Answers

The more I look at this problem, the more it seems the Chromium issue. Some days ago I posted a question, then I wanted to set up a bounty for it, and then I found your one, and I believe they are interrelated: Subpixel scroll issue, can't set scrollTop properly on Chrome 69.

There are some bug reports in Chromium issue tracker related to scale-rounding problem: link 1, link 2... I also created my own bug: link 3. There should be more information but it takes too much time to research. I think we may join efforts and draw more attention to the problem, and for example if it's Chromium responsibility, to help them with clarification and prioritisation.

user_32119320

I have the same problem with Version 76.0.3809.100 (64-Bit).

And I offset the image to compensate for the strange offset that I get in your stackbliz example too.

But with scaling 200% I need to multiply my calculated dragImage offset by 4 !!!

On 300% it's at 9
On 350% it's at 12.25

Do you see the pattern ???!

I'm afraid of my hack/fix for this problem. Not sure if it's just on windows, if it's just desktop. But for now I guess I will have to do window.devicePixelRatio^2 so I can continue my work.

user_3170830
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