[Libreoffice-bugs] [Bug 128888] New: Transparent objects causing excessive CPU usage when exporting PNG from LO Draw

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=128888

            Bug ID: 128888
           Summary: Transparent objects causing excessive CPU usage when
                    exporting PNG from LO Draw
           Product: LibreOffice
           Version: 6.3.3.2 release
          Hardware: x86-64 (AMD64)
                OS: Windows (All)
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: Draw
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: mwtjunkmail at gmail.com

Description:
When I export a slide to PNG from Draw having text converted to a curve or
polygon and the text is set transparent, Windows Task Manager shows "VERY HIGH"
for power usage for LO both while the PNG export dialog is preparing to display
on the screen and then again while saving.  

The saving process takes considerably longer than slides without transparency
(or with transparency and exporting via TIFF).

This does not occur when exporting TIFF files.

Note: This does not happen with other transparent objects, just text that's
been converted to a curve (OR POLYGON) and that curve/polygon made transparent.

Text converted to a curve/polygon but not made transparent does not hinder the
export process.



Steps to Reproduce:
1. Open LO Draw
2. Import a picture
3. On top of that picture, type some text. 
4. Convert text to a curve
5. Set the text's transparency to something other than 0.
6. Export the slide as PNG

Actual Results:
Manager shows "VERY HIGH" for power usage for LO both while the PNG export
dialog is on the screen and then again while saving. 

Expected Results:
Power usage and export time should be essentially no different for transparent
objects on a slide when exporting to PNG as opposed to another format like
TIFF.


Reproducible: Always


User Profile Reset: No



Additional Info:
Windows 10 Pro Version 1901 Build 19363.476
nVIdia GTX 1050 with driver version 441.20 released Nov 12 2019.
32GB RAM 
3770 K I7 64 Bit Processor

What I experienced happens regardless if hardware acceleration is on or off or
if Open GL is used.  I usually work with Open GL off and with hardware
acceleration and anti-aliasing on.  

Because I have not been using transparent text until now, I do not know whether
this is something new with 6.3.3.2 or would have been happening in earlier
versions.

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