<html>
<head>
<base href="https://bugs.documentfoundation.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_UNCONFIRMED "
title="UNCONFIRMED - Skia: Windows ClearType settings not observed causing poor font rendering"
href="https://bugs.documentfoundation.org/show_bug.cgi?id=134275">134275</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Skia: Windows ClearType settings not observed causing poor font rendering
</td>
</tr>
<tr>
<th>Product</th>
<td>LibreOffice
</td>
</tr>
<tr>
<th>Version</th>
<td>7.0.0.0.beta1+
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows (All)
</td>
</tr>
<tr>
<th>Status</th>
<td>UNCONFIRMED
</td>
</tr>
<tr>
<th>Severity</th>
<td>minor
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>graphics stack
</td>
</tr>
<tr>
<th>Assignee</th>
<td>libreoffice-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>josh.lackey@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>Description:
Color subpixel antialiasing with Skia+Vulkan rendering is inaccurate on BGR
ordered display, making text difficult to read.
Steps to Reproduce:
1. Options > View > Graphics Output > Use Skia for all rendering CHECKED
2. Have a display that is not compatible (i.e. BGR) with the default settings
Skia assumes
Actual Results:
All text rendering, including UI elements as well as in documents, lacks
clarity due to being iridescent around the edges
<a href="https://i.imgur.com/nJS9ntK.png">https://i.imgur.com/nJS9ntK.png</a>
Expected Results:
Fonts should render the same with Skia as they do with "Use Skia for all
rendering" unchecked
<a href="https://i.imgur.com/CU9Uj6Z.png">https://i.imgur.com/CU9Uj6Z.png</a>
The differences in the screenshots will either not be apparent or seem
*reversed* on a typical RGB monitor. e.g. on a standard RGB screen, the Skia
*off* might appear iridescent or blurry, while Skia *on* look fine. Trust me
when I say that is not the case on my display!
For more info see: <a href="http://www.lagom.nl/lcd-test/subpixel.php">http://www.lagom.nl/lcd-test/subpixel.php</a>
Reproducible: Always
User Profile Reset: Yes
Additional Info:
Technical note:
Skia requires a preprocessor directive in order to read the ClearType
parameters from system settings, which includes pixel order as well as contrast
and gamma.
<a href="https://skia.googlesource.com/skia/+/refs/heads/master/src/ports/SkTypeface_win_dw.cpp#395">https://skia.googlesource.com/skia/+/refs/heads/master/src/ports/SkTypeface_win_dw.cpp#395</a>
<a href="https://docs.microsoft.com/en-us/dotnet/framework/wpf/advanced/cleartype-registry-settings">https://docs.microsoft.com/en-us/dotnet/framework/wpf/advanced/cleartype-registry-settings</a>
This might explain the SK_GAMMA_APPLY_TO_A8 issue described in this commit:
<a href="https://cgit.freedesktop.org/libreoffice/core/commit/external/skia?id=1ad3f6b8d9e0ef1e921c3ed5526ea352d67265cf">https://cgit.freedesktop.org/libreoffice/core/commit/external/skia?id=1ad3f6b8d9e0ef1e921c3ed5526ea352d67265cf</a>
Adding #define SK_FONT_HOST_USE_SYSTEM_SETTINGS 1 to config_skia.h.in would
probably solve the issue.
<a href="https://cgit.freedesktop.org/libreoffice/core/tree/config_host/config_skia.h.in">https://cgit.freedesktop.org/libreoffice/core/tree/config_host/config_skia.h.in</a>
Then the user could tune the level of ClearType antialiasing using Windows
built-in the "Adjust ClearType Text" Control Panel applet if it was not
satisfactory. However, Windows usually sets the correct subpixel order by
default.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the assignee for the bug.</li>
</ul>
</body>
</html>