389459 - lines appear in images if you scroll the page while they're still loading, and layout.css.dpi is greater than or equal to 144

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Daniel Brooks [:db48x]]

These lines can be both horizontal and vertical, depending on which direction you scroll the page. I have layout.css.dpi set to 144, and the black lines are two pixels wide. When I set it to 240, the lines are 3 pixels wide. They cover only the image(s) that are loading, not the rest of the page. Once the image is fully loaded, these lines no longer occur while scrolling, though any existing lines remain on the screen until that part of the image is forced to redraw, for example by being scrolled off screen and back.

I tried to take a screenshot of this, but that caused the window to be redrawn and the lines to disappear.

Comment 1

[Daniel Brooks [:db48x]]

Oh, and I'm the trunk, build id is not too old at 2007072116

Comment 2

[Daniel Brooks [:db48x]]

Ah, and the color of the line is the background color, it's not always black. Try doing view image on that page, and you'll get white lines.

Comment 3

[Eli Friedman]

Attachment: Patch

The arithmetic here is just weird; do something sane-looking.

Comment 4

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

Comment on attachment 274021 [details] [diff] [review]
Patch

This looks good, though I'd ping dbaron since he put that code in initially, and i'm not sure why now.  But it might have been a thinko.

Comment 5

[Eli Friedman]

It's not dbaron's code; see Bug 337424.

Comment 6

[Daniel Brooks [:db48x]]

You could take out the comment too.

Comment 7

[Eli Friedman]

I'll do that when I check in.

Comment 8

[Eli Friedman]

Comment on attachment 274021 [details] [diff] [review]
Patch

Fix for a minor bug in painting scaled images while they are loading.  Extremely low-risk; the worst possible side-effect is a rounding error painting images while loading.

Comment 9

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

Comment on attachment 274021 [details] [diff] [review]
Patch

a19=dbaron

Comment 11

[Eli Friedman]

Checked in.