https://bugs.documentfoundation.org/show_bug.cgi?id=163352
Bug ID: 163352
Summary: Horizontal scaling of text within an embedded SVG
image is rendered at the wrong scale
Product: LibreOffice
Version: 24.2.4.2 release
Hardware: All
OS: Windows (All)
Status: UNCONFIRMED
Severity: normal
Priority: medium
Component: graphics stack
Assignee: [email protected]
Reporter: [email protected]
Description:
When importing an SVG image that has text that has been scaled horizontally (in
other words, text with horizontal scaling that differs from its vertical
scaling), the text is rendered with the wrong horizontal scale.
This bug first appeared in LO 24.2.4.1 (LO 24.2.3.2 works properly). The bug
still exists in the current LO 24.8.2.1 version. The bug affects Windows
platforms, but not Linux.
My guess is that the bug might have been introduced with this commit, but
that's just a guess (more about that below):
https://git.libreoffice.org/core/+/cc3663bbaed4f65d64154e5f9abb51a5f622f710
Steps to Reproduce:
Open the attached ODG file in a version of LO >= 24.2.4.1 on Windows. The file
contains an embedded SVG image with 3 lines of monospaced text (Liberation Mono
font). All lines use the same font size (height). The top line has 10
characters without any horizontal scaling applied. The middle line has 5
characters with a horizontal:vertical scaling of 2:1 applied. The bottom line
has 20 characters with a horizontal:vertical scaling of 0.5:1 applied.
The original SVG image file is also attached for reference.
Actual Results:
All 10 characters of the top line of text are rendered properly. The middle
line renders only 3 of the 5 characters, but is the same total length as the
top line, implying a horizontal scaling of 10/3=3.333, not 2 (a scaling error
factor of 1.67). The bottom line renders only 12 of the 20 characters, but is
the same total length as the top line, implying a horizontal scaling of
10/12=.833, not 0.5 (a scaling error factor of 1.67). A PDF is attached which
illustrates the incorrect rendering generated by LO 24.2.4.1 on Windows. The
same result is obtained when using LO 24.8.2.1.
Interestingly, using FontForge to inspect the font metrics of the font used
(Liberation Mono Regular) reveals that the font has a design height of 2048 and
a width of 1229. That works out to a ratio of 1.666, which is the same as the
scaling error factor, so that may be a clue as to what is going wrong.
Based on the above observations, these lines of code in the above referenced
commit seem like possible candidates for causing the error:
https://github.com/LibreOffice/core/blame/cc3663bbaed4f65d64154e5f9abb51a5f622f710/drawinglayer/source/primitive2d/textlayoutdevice.cxx#L183
https://github.com/LibreOffice/core/blame/cc3663bbaed4f65d64154e5f9abb51a5f622f710/drawinglayer/source/processor2d/vclprocessor2d.cxx#L417
Expected Results:
Properly rendered, all characters of each line should be displayed, and all
three lines should appear to be the same total length. A PDF is attached which
illustrates the proper rendering generated by LO 24.2.3.2.
Reproducible: Always
User Profile Reset: Yes
Additional Info:
Version: 24.2.4.1 (X86_64) / LibreOffice Community
Build ID: bd07154d43e1c17c8045539e3a56d206798fe486
CPU threads: 4; OS: Windows 10.0 Build 19045; UI render: Skia/Raster; VCL: win
Locale: en-US (en_US); UI: en-US
Calc: threaded
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