363220 - non-dotted non-1px borders sometimes drawn offset 1 pixel to the left (pixel snapping in FillPolygon?)

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Ori Avtalion (salty-horse)]

User-Agent:       Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9a1) Gecko/20061208 Minefield/3.0a1
Build Identifier: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9a1) Gecko/20061208 Minefield/3.0a1

As seen in the test-case, the first div is displayed correctly but the second div has it's top and bottom borders shifted to the right.

The only difference between the left and right div, is that the first is inside a container div with width: 30% (rendered correctly), and the second one is inside a div with width: 70%

Reproducible: Always

Steps to Reproduce:
See testcase

Comment 1

[Ori Avtalion (salty-horse)]

Attachment: testcase

Comment 2

[Ori Avtalion (salty-horse)]

The bug occurs in the trunk, but not in Firefox 2.0

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Is this a recent regression?

Comment 4

[Ori Avtalion (salty-horse)]

I noticed that the yellow line on the right is clearly visible on the 2006-04-22 build and not visible on the 2006-04-21 build.

bug 328241 is probably at fault.

I also noticed that the 2006-04-21 build has other problems when displaying the testcase. To the right and the left of each of the 6 colored blocks there is a 1-pixel column of "faded" color.

Comment 5

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I'm guessing that there's something wrong with the pixel-snapping code for FillPolygon, actually.  I have another testcase that I'll attach.

dotted borders, 1px solid borders, background colors, and tiled background images all seem consistent in how they pixel-snap, but wider solid borders don't match.

Comment 6

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: additional testcase

Comment 8

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I tried making an equivalent testcase for top/bottom borders and couldn't find any problems.

Comment 9

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

For what it's worth, this doesn't happen on Windows, so it's probably actually a lower-level problem.  It's hard to tell whether it happens on Mac given bug 361523.

Comment 10

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Er, it does happen on Windows.  I think I was testing in IE :-(.

Comment 11

[Dão Gottwald [:dao]]

this looks a bit like bug 369864 to me, although that one is said to be a regression of bug 177805.

Comment 12

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Will be fixed by bug 368247 (in my tree).

Comment 14

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Fixed by patch for bug 368247.

Comment 15

[Bruno Fassino]

I still see what looks like the same problem in the following build:

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a5pre) Gecko/20070514 Minefield/3.0a5pre

but only inside a table having  border-collapse: collapse.
I will attach a test case where varying windows width the border of a table cell is sometimes drawn 1px to the left.

Comment 16

[Bruno Fassino]

Attachment: test case with table

shows the problem in Gecko/20070514 Minefield/3.0a5pre

Comment 17

[philippe (part-time)]

(In reply to comment #15)
> I still see what looks like the same problem in the following build:
> 
> Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a5pre) Gecko/20070514
> Minefield/3.0a5pre
> 
> but only inside a table having  border-collapse: collapse.
> I will attach a test case where varying windows width the border of a table
> cell is sometimes drawn 1px to the left.
> 
Please file a new bug.