1096885 - SVG image as CSS background has left edge flattened/cropped, with fractional pixel sizing & positioning

Status: NEW

(Core :: SVG, defect)

Description

[yem_salat]

Attachment: scr.png

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:36.0) Gecko/20100101 Firefox/36.0
Build ID: 20141101211637

Steps to reproduce:

http://codepen.io/anon/pen/yyBZKG


Actual results:

The left side is slightly cut off when background-size is 100%

http://i.imgur.com/oX4x1S7.png




Expected results:

Shouldn't be cut out at all, works correctly in Chrome and Opera (Blink)

Comment 1

[Vladimir]

Exemple: http://codepen.io/Novitsky/pen/bNbOQg
Screenshot: http://www.imageup.ru/img278/1940138/77651918.png

Comment 2

[Vladimir]

UPD: OS Windows 8.1

Comment 3

[Robert Longson [:longsonr]]

Seems significantly better on trunk. https://nightly.mozilla.org/ what do you think Vladimir?

Comment 4

[Daniel Holbert [:dholbert]]

To be clear, the screenshot from the reporter in comment 0 *is* from trunk, per the UA string in that comment. It also matches what I see on my linux nightly -- the left edge is flattened a bit.
  ( --> Canceling needinfo, as I think Robert might've missed the comment 0 screenshot/UA-string.)

Seth, do you know of any ongoing imagelib refactoring that might help here?

Comment 5

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

Here's the reporter's testcase, with the SVG simplified a bit (and encoded as a data URL), and with the HTML simplified a bit as well.

Note that the HTML has a fractional pixel values for positioning and sizing.  If I change *either* the "width" value or the "padding-left" value to be a whole number, then the flattening goes away.  So, this is clearly a rounding/snapping bug at some level.

Comment 6

[Robert Longson [:longsonr]]

The screenshot in comment 1 looks like it isn't from trunk, the one in comment 0 looks like it is. Hence my confusion.

Comment 7

[Loic]

In Nightly, the rendering is better at default zoom level, but if I zoom out/in, I can the see the bad rendering again.

Comment 8

[yem_salat]

As Daniel mentioned - my screen is from nightly trunk on linux, the result is the same on on regular firefox (also linux)

Everything looks fine on a Mac.

Vladimir's screen is made on regular ff in windows 8.1, setting background-size to 99% does not help his case, I asked him to re-test on latest nightly.

Comment 9

[yem_salat]

Vladimir reports that on Windwows 8.1 on nightly build the situation is the same as on linux: http://www.imageup.ru/img278/1941213/77651919.png

Comment 10

[Seth Fowler [:seth] [:s2h]]

(In reply to Daniel Holbert [:dholbert] from comment #4)
> Seth, do you know of any ongoing imagelib refactoring that might help here?

There's no ongoing refactoring that might help here. This is just a numerical accuracy bug that somehow didn't get fixed by bug 1037713.

Most of the other bugs like that involve issues with the layers system. I wonder if there's something SVG-specific here? (i.e., the bug is either in VectorImage or in the underlying SVG code)

I'll make this depend on bug 1037713 so it has a connection to the other numerical accuracy bugs.