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Fix getPointer on touch devices #4866

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merged 2 commits into from
Apr 8, 2018
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nmorel
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@nmorel nmorel commented Mar 29, 2018

When dragging an object on touch device on top or left edge of a screen, the getPointer function returns an incorrect value (NaN).
To reproduce it, you can use the following demo : http://fabricjs.com/intersection and move an object to the left side.

When clientX and pageX are 0, the internal _getPointer method returns event[clientProp] which is undefined instead of 0.

pointer = event[touchProp][0][pageProp] - (event[touchProp][0][pageProp] - event[touchProp][0][clientProp]);
}

if (!pointer && pointer !== 0) {
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isn't this better as typeof pointer === 'undefined' ? that is the real meaning of it, if yuo did manage to assign anything to pointer in the first if, right?

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yea it should work the same. I'll change it.

If the pointer is at x=0 or y=0, it returns NaN.
@asturur
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asturur commented Apr 8, 2018

i just noticed that pageProp - ( pageProp - clientProp) is just equal to +clientProp

@asturur asturur merged commit fe55cf4 into fabricjs:master Apr 8, 2018
@asturur asturur mentioned this pull request May 8, 2018
thiagocunha pushed a commit to thiagocunha/fabric.js that referenced this pull request Nov 18, 2019
* Fix getPointer on touch devices

If the pointer is at x=0 or y=0, it returns NaN.

* Update dom_event.js
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2 participants