Bug 2124013 - Incorrect rendering triggered by cairo CAIRO_OPERATOR_SATURATE with subpixel positioning [NEEDINFO]
Summary: Incorrect rendering triggered by cairo CAIRO_OPERATOR_SATURATE with subpixel ...
Keywords:
Status: NEW
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: pixman
Version: CentOS Stream
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Adam Jackson
QA Contact: Desktop QE
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2022-09-03 23:00 UTC by Benjamin Gilbert
Modified: 2023-08-02 04:29 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed:
Type: Bug
Target Upstream Version:
Embargoed:
bgilbert: needinfo? (ndegraef)

Attachments (Terms of Use)
Test program (888 bytes, text/x-csrc)
2022-09-03 23:00 UTC, Benjamin Gilbert 		no flags Details
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Links
System ID Private Priority Status Summary Last Updated
Github openslide openslide issues 278 0 None closed Images at downsampled levels are distorted (MRXS). 2022-09-03 23:00:01 UTC
Gitlab redhat/centos-stream/rpms pixman merge_requests 2 0 None opened Fix bilinear filter computation in wide pipeline 2022-09-10 05:26:05 UTC
Red Hat Issue Tracker RHELPLAN-133184 0 None None None 2022-09-03 23:03:39 UTC

Description Benjamin Gilbert 2022-09-03 23:00:02 UTC 
Created attachment 1909395 [details]
Test program

Description of problem:
pixman 0.38.x has a regression that causes incorrect rendering in some circumstances.  This can be triggered by the use of cairo with CAIRO_OPERATOR_SATURATE and subpixel positioning, and causes OpenSlide <https://openslide.org/> to produce incorrect output.

Version-Release number of selected component (if applicable):
0.38.4-2.el8.x86_64

How reproducible:
Always

Steps to Reproduce:
Compile and run attached test program.

Actual results:
Program prints "Failed"

Expected results:
Program prints "OK"

Additional info:
This is fixed upstream in https://gitlab.freedesktop.org/pixman/pixman/-/commit/8256c235d9b3854d039242356905eca854a890ba, which is in pixman 0.40.0.
Comment 1 Benjamin Gilbert 2022-09-10 05:26:05 UTC 
Fix posted in https://gitlab.com/redhat/centos-stream/rpms/pixman/-/merge_requests/2.
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