1369730 - Animated canvas item is draggable

Status: RESOLVED INVALID

(Core :: Graphics: Canvas2D, defect)

Description

[Paul Silaghi, QA [:pauly]]

[Affected versions]:
- 53.0.3, 54b13, 55.0a1 (2017-06-02)

[Affected platforms]:
- Ubuntu 14.04, OS X 10.11, Win 10

[Steps to reproduce]:
1. Open http://flashcanvas.net/examples/www.chiptune.com/kaleidoscope/
2. Drag the animation to the browser edges

[Expected result]:
- Animated item shouldn't be draggable

[Actual result]:
- Animated item is draggable

[Regression range]:
- tbd, doesn't reproduce on Fx 47

Comment 1

[YF (Yang)]

I don't see the difference, can you explain it? such as a screenshot.

Comment 2

[Paul Silaghi, QA [:pauly]]

https://www.screencast.com/t/0ftPcrpsGk36

Comment 3

[YF (Yang)]

[Actual result]:
- Dragging is suppressed, but dragged thumbnail are displayed.


Regression range:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=1f16d3da9280e40ada252acf8110b91ee1edbb08&tochange=f05a1242fb29023bd7ebc492897ed3d6907733c7

Comment 4

[Paul Silaghi, QA [:pauly]]

More specific pushlog: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=7f2f44eaea09c02079d8f1a0be777cd39776712e&tochange=4f139d664ccc461f43174119bfe356841482e6ca

Comment 5

[Mats Palmgren (inactive)]

Thanks for the regression range.  Bug 1258476 is indeed what changed
the behavior.  However, I consider it to be an improvement over
the old behavior.

> [Expected result]:
> - Animated item shouldn't be draggable

Can you explain why you think that?

The <canvas> on the page is a child of a <a href> element - which *should* be
draggable per spec and that's what we drag.  There is *no change* in that 
behavior before/after bug 1258476.  The change is only in the drag feedback
we display.  I consider the new behavior an improvement since it more
accurately depicts what is actually being dragged and this is how we
normally render drag feedback.

Comment 6

[Mats Palmgren (inactive)]

Attachment: Simpler testcase

Simpler testcase for comparing the behavior:

<a href="#"><img width=100 height=100 src="https://resources.whatwg.org/logo.svg"></a>

When dragging this link, we show the image as a drag cursor.
I see no reason why the reported page should behave differently.

Comment 7

[Paul Silaghi, QA [:pauly]]

(In reply to Mats Palmgren (:mats) from comment #6)
> Simpler testcase for comparing the behavior:
> <a href="#"><img width=100 height=100
> src="https://resources.whatwg.org/logo.svg"></a>
Note that the testcase also displays the thumbnail on dragging in Chrome compared to the initial page that didn't display it - img vs canvas.

> Can you explain why you think that?
I just compared to other browsers (Chrome, Opera) and also didn't look properly to me to be able to drag an active animation.
But, if everything is per spec, feel free to close the bug.
Thank you.

Comment 8

[Mats Palmgren (inactive)]

The link should definitely be draggable, whether it's an image, canvas, video
or some other content inside it doesn't matter really.

What we render as the drag feedback is a different issue.  Currently, we just
render the content being dragged as it's rendered on the page (scaled down to
a reasonable size of needed).  Please file a separate bug if you think we
should render something else, because that's more of an UX decision.