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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SNA] Inconsistency in line visibility when using different line-widths"
href="https://bugs.freedesktop.org/show_bug.cgi?id=93280">93280</a>
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<th>Summary</th>
<td>[SNA] Inconsistency in line visibility when using different line-widths
</td>
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<th>Product</th>
<td>xorg
</td>
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<th>Version</th>
<td>git
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>Driver/intel
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<th>Assignee</th>
<td>chris@chris-wilson.co.uk
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<th>Reporter</th>
<td>romain.vavassori@hotmail.com
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=120376" name="attach_120376" title="archive containing program, patch and screenshots of the issue">attachment 120376</a> <a href="attachment.cgi?id=120376&action=edit" title="archive containing program, patch and screenshots of the issue">[details]</a></span>
archive containing program, patch and screenshots of the issue
There is an inconsistency in line visibility for lines of zero length
depending on the line-width attribute. This happens when using SNA instead of
UXA with xf86-video-intel driver.
I have done a program to show this issue (see test.c and screenshots in
attachment). The program draw a grid of sample lines with varying parameters:
- following X axis: increasing line length (0 to 2)
- following Y axis: increasing line-width (1 to 3)
Normally we expect to have the same behavior on each row of the grid (either
visible lines or not) but in the case of zero length lines, we obtain a visible
line only if line-width == 1.
>From the docs [1] it is said that for a line-width >= 1, zero length lines
should not be visible when drawn with CapButt attribute (as in our case).
I have put a patch in attachment solving the issue (patch.diff). Bug and patch
have been tested with Debian Jessie official version (2.99.917) and also with
git latest commit (da9ad388).
[1] <a href="http://tinf2.vub.ac.be/~dvermeir/manual/xlib/GC/manipulating.html">http://tinf2.vub.ac.be/~dvermeir/manual/xlib/GC/manipulating.html</a>
environment
-----------
uname -a:
Linux crunchbang 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1 (2015-05-24)
x86_64 GNU/Linux
lspci -nn:
00:02.0 VGA compatible controller [0300]: Intel Corporation 4th Gen Core
Processor Integrated Graphics Controller [8086:0416] (rev 06)
versions:
- xorg: Debian Jessie official releases
- xf86-video-intel: bug present in either Debian Jessie release (2.99.917) or
latest git commit (da9ad388)
The driver used is i915 with SNA.
I can provide other logs if needed.</pre>
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