Bug 152609

Summary:	Bad qt5 PNG rendering
Product:	LibreOffice	Reporter:	Roland Baudin <roland65>
Component:	Impress	Assignee:	Not Assigned <libreoffice-bugs>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	ilmari.lauhakangas, roland65
Priority:	medium
Version:	7.4.3.2 release
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
Crash report or crash signature:		Regression By:
Attachments:	Test presentation Screenshot of renbdering with gen engine Screenshot of rendering with gtk3 engine Screenshot of rendering with qt5 engine (BAD)

Description Roland Baudin 2022-12-20 09:07:22 UTC

Description:
PNG images are badly rendered when using qt5 engine.

Examples:

test-png-rendering.odp => Impress presentation with a PNG drawing

test-gen-rendering.png => Screenshot of presentation with gen engine (PNG rendering OK)

test-gtk3-rendering.png => Screenshot of presentation with gtk3 engine (PNG rendering OK)

test-qt5-rendering.png => Screenshot of presentation with qt5 engine (PNG rendering KO, antialiasing problem?)

This always reproducible and also happens in Writer and Draw.

LibreOffice
-----------

Version: 7.4.2.3 / LibreOffice Community
Build ID: 40(Build:3)
CPU threads: 48; OS: Linux 5.15; UI render: default; VCL: qt5 (qfont+xcb)
Locale: fr-CH (fr_FR.UTF-8); UI: fr-FR
Ubuntu package version: 1:7.4.2~rc3-0ubuntu0.22.04.1~lo1
Calc: threaded


System
------

Ubuntu 22.04.1 LTS 64 bits


For the tests, I used a fresh LibreOffice profile in a fresh user profile.
 

Actual Results:
Bad PNG rendering with qt5 engine

Expected Results:
Good PNG rendering with qt5 engine


Reproducible: Always


User Profile Reset: Yes

Additional Info:
--

Comment 1 Roland Baudin 2022-12-20 09:08:00 UTC

Created attachment 184256 [details]
Test presentation

Comment 2 Roland Baudin 2022-12-20 09:08:32 UTC

Created attachment 184257 [details]
Screenshot of renbdering with gen engine

Comment 3 Roland Baudin 2022-12-20 09:08:56 UTC

Created attachment 184258 [details]
Screenshot of rendering with gtk3 engine

Comment 4 Roland Baudin 2022-12-20 09:09:20 UTC

Created attachment 184259 [details]
Screenshot of rendering with qt5 engine (BAD)

Comment 5 Buovjaga 2022-12-20 09:37:08 UTC

The qt5 backend is still experimental and you should not be using it. You can see if running with the environment variable SAL_VCL_QT5_USE_CAIRO=1 makes a difference.

Comment 6 Roland Baudin 2022-12-20 12:34:52 UTC

Ok, thanks for the tip. Indeed, when launching LibreOffice with:

SAL_USE_VCLPLUGIN=qt5 SAL_VCL_QT5_USE_CAIRO=1 libreoffice

the PNG rendering is now OK.

Comment 7 Buovjaga 2022-12-20 13:08:36 UTC

Thanks for testing. I think we can close.

Some distributions like Lubuntu want to default to qt5 for some reason and we have repeatedly advised them to stop. They refuse to listen, unfortunately.