Open Bug 870524 Opened 11 years ago Updated 4 months ago

Linear gradient rendering fails on tall pages. Windows, Linux, Android.

Categories

(Core :: Web Painting, defect, P3)

defect

Tracking

()

People

(Reporter: bugs, Unassigned)

References

(Blocks 1 open bug, )

Details

(Keywords: testcase)

Attachments

(1 file, 1 obsolete file)

579 bytes, application/xhtml+xml
Details
Encountered this on a production site with a linear gradient from light grey to slightly darker grey.
Scrolling down a long page under Windows, the background suddenly turned black.

Fiddling with toggling CSS settings, unfocusing firefox, scrolling up and down revealed rendering bugs shifted.

Sometimes all white would be shown, sometimes white and black with chunks.  Sometimes the gradient would repeat.

http://m8y.org/tmp/testcase339.xhtml is a quick test page.  Will attach.

If I scroll down in Linux, the gradient restarts about half way down.  When I scroll all the way to the end, I see blue, red and green instead of just red.  If I focus away, it corrects itself, although errors reappear on scrolling again.

Under Windows, green (the background colour) begins about half-way down.  If I unfocus Firefox with the green filling the viewport, the green jumps to fill all of it.

Under Android (Gingerbread, SPH-M930), green appears half-way down, but if I keep scrolling, the gradient starts over.  If I switch to another tab in Android, and switch back, the green behaves similar to Windows.

OSX 10.7.5 appears to work correctly.

Tested in Firefox Nightly on all platforms.  Tried disabling layers accel under Linux, didn't help.
Attached file Demo of problem (obsolete) —
Attached file Actual testcase
Sorry, misread the fields in the attachment form.
Comment on attachment 747574 [details]
Demo of problem

>Testcase
Attachment #747574 - Attachment is obsolete: true
FWIW, I can confirm this on Win 7 only with GDI i.e. HWA off.
Keywords: testcase
I can not reproduce this symptom on win10/ubuntu 16/mac....
Priority: -- → P3
Component: Layout: View Rendering → Layout: Web Painting
Severity: normal → S3

BTW, I retested this under linux with hardware acceleration enabled (webrender).
Green was no longer present when scrolling. However, if I hit "home" to jump up to the top, there was a distinct flash of green.
Curiously this flash did not appear if I added (for test purposes), links to jump from the bottom to the top and vice versa, so perhaps Home/End uses a different mechanism such as a very fast scroll from the anchor method.

The behaviour on android seems to be the same.

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