Created attachment 188456 [details] Comparing output in Linux and Windows Description: With Harfbuzz as the font rendering engine in LibreOffice, it is expected that font rendering output on display and print are the same on different platforms. But, in reality there are slight differences. For example, in this case fonts are displayed slightly different on Linux, which causes the characters to overlap. Steps to Reproduce: 1. Open attachment 188277 [details] in LO Writer dev master on Windows 2. Open the same file in LO Writer dev master on Linux 3. Compare the outputs on Windows and Linux display Actual Results: The outputs on display are different, and the characters sometimes overlap. For example, in the last line the starting » falls on the next character, which is ب and there is not (slight) space between them. Please look at «به همین دلیل» and other places in the start of double quotes «». Expected Results: Output on display in different platforms should be similar, and anyway the characters should not overlap in different zoom levels. There should be a slight space between » and ب in the last line. For a comparison, the results are normalized (for size) and compared side by side in the attachment with 110% zoom level on both Windows and Linux. LO on Windows and Linux were built from the same git revision. Reproducible: Always User Profile Reset: No Additional Info: LO 24.2 dev master on Linux: Version: 24.2.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: bb01ef3865c406f322d6e656faba2191aaeeb6da CPU threads: 12; OS: Linux 5.19; UI render: default; VCL: gtk3 Locale: en-US (en_US.UTF-8); UI: en-US Calc: CL threaded LO 24.2 dev master on Windows: Version: 24.2.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: bb01ef3865c406f322d6e656faba2191aaeeb6da CPU threads: 12; OS: Windows 10.0 Build 22621; UI render: Skia/Vulkan; VCL: win Locale: en-US (en_US); UI: en-US Calc: CL threaded
Created attachment 188458 [details] PDF output from LibreOffice on Windows Please note that the difference is on display, and I see no difference in PDF output. I am putting the PDF files here for the reference.
Created attachment 188459 [details] PDF output from LibreOffice on Linux As declared above, this is also for the reference. The difference is on display.
Looks like difference in DPI to me, does the Windows machine have a hidpi screen and Linux machine has a regular one?
(In reply to خالد حسني from comment #3) > Looks like difference in DPI to me, does the Windows machine have a hidpi > screen and Linux machine has a regular one? Windows machine has a higher resolution and 3x scaling, Linux machine also uses 2x scaling. So, both are considered HIDPI. qtdiag reports: Linux machine Physical DPI: 142 (approximate, slightly different on x and y) Logical DPI: 192 DevicePixelRatio: 1 Windows machine Physical DPI: 78 (approximate, the same on x and y) Logical DPI: 96 (native 288) DevicePixelRatio: 3 I scaled the Linux screenshot by the factor of 1.5 to create the combined screenshot.
I don't use display scaling. I installed B Nazanin font and looked at the example file. I don't see the overlap in any zoom level. Arch Linux 64-bit, X11 Version: 24.2.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: 6ee0f9f02f7255339e18ab9e6189b2200bb71e6e CPU threads: 8; OS: Linux 6.4; UI render: default; VCL: kf5 (cairo+xcb) Locale: fi-FI (fi_FI.UTF-8); UI: en-US Calc: threaded Built on 5 September 2023
Can't see an overlap either on Ubuntu 22.04 + GNOME 42.9, 1× scaling, DPI 96×96, display 1600×900, with: Version: 24.8.0.0.alpha1+ (X86_64) / LibreOffice Community Build ID: ae798781ef4df7a1fdef13af0bc459bf4f6e7b4c CPU threads: 8; OS: Linux 6.5; UI render: default; VCL: gtk3 Locale: en-AU (en_AU.UTF-8); UI: en-US Calc: CL threaded
Created attachment 194269 [details] Screencast comparing output from Windows and Linux This is a screencast created from the attachment 188456 [details] using GIMP, putting two outputs on Linux and Windows on different layers, showing/hiding them repeatedly.
Makes using different backends on the same linux machine any difference in font rendering? FWIW: A test file with the required font embedded makes life easier and makes sure everyone using the same font version