[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 adam.m.fontenot+do...@gmail.com changed: What|Removed |Added Resolution|WONTFIX |--- Status|RESOLVED|REOPENED --- Comment #14 from adam.m.fontenot+do...@gmail.com --- (In reply to László Németh from comment #9) > Pair kerning is for high quality typesetting. It's a de facto standard in > document editing, not only in desktop publishing. Thanks for your comment. I was surprised to see a commit reverting this so quickly and in fact I was going to raise the issue of rendering to PDF myself. Indeed, I'm worried that a naive solution that simply changes the default would break high quality PDF rendering. (This hadn't yet occurred to me when I made the suggestion.) > As a workaround for the reported problem, enable "View PDF after export", so > clicking on the PDF export icon, you can see the result with subpixel-based > rendering, too. Yes, this is exactly the workaround I've been using when writing anything in LibreOffice for years now. Write a few paragraphs without proofreading them, export to PDF, then read back the PDF. That's the only way to avoid a miserable experience trying to edit/read a document in LibreOffice at the moment. Although I'm sure you're aware of this, I want to be clear that the status quo is very bad. A huge number of LibreOffice users have complained about its font rendering over the last few years, and so I was surprised to learn that there's seemingly no active effort to fix the complete lack of subpixel positioning for glyphs in the editor. --- As I said above, I do agree that simply disabling the pair kerning default isn't acceptable because of high quality printing and PDF output. But I still don't think this should be a WONTFIX - there's another alternative. Leave pair kerning enabled but only apply the setting to output that actually *can* be meaningfully kerned - i.e. only the contexts which support accurate subpixel positioning. So you will continue to get the high quality desktop publishing output, while the LibreOffice editor component which handles font rendering will silently ignore the setting when rendering text (for example, in the Writer window). Alternatively, I request that a separate setting be added to disable pair kerning *only* in the editor components while leaving it enabled for desktop publishing cases. I'd also point out that if casual users discover that having pair kerning enabled makes their documents look worse, they will simply disable it, heavily reducing the quality of their published documents. Writer is a WYSIWYG editor after all! --- I'm reopening the bug so that the proposal above can be discussed. I apologize if reopening a closed bug is against etiquette on this issue tracker - this is my first issue opened here. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 Heiko Tietze changed: What|Removed |Added Assignee|heiko.tietze@documentfounda |libreoffice-b...@lists.free |tion.org|desktop.org Resolution|--- |WONTFIX Severity|normal |enhancement Status|ASSIGNED|RESOLVED --- Comment #13 from Heiko Tietze --- What a pity that we have no simple solution. If you insist in disabled pair kerning, please uncheck it for the Default Paragraph Style, save as template and make this the default for new documents. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 Heiko Tietze changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|libreoffice-b...@lists.free |heiko.tietze@documentfounda |desktop.org |tion.org --- Comment #8 from Heiko Tietze --- This was introduced with https://bz.apache.org/ooo/show_bug.cgi?id=16874. But let's give it a try to disable this option by default https://gerrit.libreoffice.org/c/core/+/119168 -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 --- Comment #7 from adam.m.fontenot+do...@gmail.com --- (In reply to Ming Hua from comment #3) > I don't know much about text rendering so all I can add is a screenshot with > 7.2.0 Beta1 on Windows 10, showing similar differences with or without pair > kerning. Thanks for your effort to get this looked at. The issue with using Windows as a comparison is that by default Windows hints so strongly that much of the subpixel nuance is lost anyway. I actually find the screenshot you posted very difficult to read because of the amount of distortion to the glyph shapes. IIRC, the developers of Microsoft Word agree with me, and they actually wrote their own text rendering engine for Word so that they don't have to use ClearType. (It's been a long time since I looked at anything Windows related, I could be misremembering.) (In reply to V Stuart Foote from comment #5) > Cross platform we went to harfbuzz at 5.3.0.3; any improvement to sub-pixel > rendereing needed to improve font provided hinting for kerning will only > come with resolution of bug 103322 This was indeed what I was worried about. My thinking, though, is that this bug shouldn't depend on that one. If LibreOffice doesn't support rendering at arbitrary subpixel offsets, then pair kerning (which depends heavily on being able to render at precise offsets) is sort of useless / broken. As far as I can tell, in LibreOffice's present state, pair kerning is effectively adding or subtracting a small random value from the desired glyph offset, which then gets rounded by the renderer into whole pixels. It's really not surprising that the result is frequently worse than no pair kerning at all. For that reason, it seems to make sense to consider disabling it until bug 103322 is fixed. Can anyone show that having it enabled confers any definite advantage to font rendering under Linux at present? My screenshots of LibreOffice's rendering would seem to suggest that the results of having it enabled are uniformly worse. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 Heiko Tietze changed: What|Removed |Added Ever confirmed|0 |1 Status|UNCONFIRMED |NEW --- Comment #6 from Heiko Tietze --- Might be not so easy to switch kerning off for every PS and CS. But thanks for the bug report. Wish each would be as clear as this. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 V Stuart Foote changed: What|Removed |Added Depends on||103322 CC||vstuart.fo...@utsa.edu Version|7.1.4.2 release |5.3.0.3 release --- Comment #5 from V Stuart Foote --- Cross platform we went to harfbuzz at 5.3.0.3; any improvement to sub-pixel rendereing needed to improve font provided hinting for kerning will only come with resolution of bug 103322 Referenced Bugs: https://bugs.documentfoundation.org/show_bug.cgi?id=103322 [Bug 103322] Use floating point for glyph positioning in VCL -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 Ming Hua changed: What|Removed |Added Keywords|needsDevEval|needsUXEval -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 Ming Hua changed: What|Removed |Added CC||libreoffice-ux-advise@lists ||.freedesktop.org Whiteboard| QA:needsComment| OS|Linux (All) |All Keywords||needsDevEval --- Comment #4 from Ming Hua --- Unfortunately there don't seem to be LO developers actively working on text rendering right now. Let's see if the UX team want to have a look at this and discuss the possibility of turning off pair kerning by default. The advantage seems not clear-cut to me, and I don't think it's possible to turning it off only for certain fonts. For people not familiar with pair kerning: The option to turn it on/off is located at the "Position" tab of the character formatting or paragraph style dialog. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 --- Comment #3 from Ming Hua --- Created attachment 173480 --> https://bugs.documentfoundation.org/attachment.cgi?id=173480=edit Screenshot of similar comparison under Windows (In reply to adam.m.fontenot+docfo from comment #0) > This might be the cause of > https://bugs.documentfoundation.org/show_bug.cgi?id=128987 but I can't tell > because I don't use Windows. I don't know much about text rendering so all I can add is a screenshot with 7.2.0 Beta1 on Windows 10, showing similar differences with or without pair kerning. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 QA Administrators changed: What|Removed |Added Whiteboard|| QA:needsComment -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 --- Comment #2 from adam.m.fontenot+do...@gmail.com --- Created attachment 173023 --> https://bugs.documentfoundation.org/attachment.cgi?id=173023=edit Screenshot showing lack of subpixel positioning Screenshot shows 12pt Arial rendered at 100% zoom in LibreOffice. Screenshot was run through a script that shows subpixels in a 3x3 grid and then point upscaled 5x. Identical glyphs have the same subpixel offset. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 --- Comment #1 from adam.m.fontenot+do...@gmail.com --- Follow up: Looking at https://bugs.documentfoundation.org/show_bug.cgi?id=103322 again, it's worth pointing out that if I'm reading the following correctly, LibreOffice is not using subpixel positioning at all. > We should switch to using floats to store glyph positions instead, which > would make the rounding errors less visible. It would also allow us to > benefit from sub-pixel positioning support in the graphics libraries we use. Indeed, from testing this appears to be the case. If you look at the screenshot I'm about to attach, you'll see that each glyph on the first line has exactly the same subpixel offset as the corresponding glyph on the second line. This isn't the case with a properly behaving FreeType renderer (tested in KWrite). That's why the result of that bug is a bunch of bad glyph positioning problems. If you type a repeated character like "mmm", the text layout engine will (in 12 pt Arial) put each "m" slightly too close together because it lacks subpixel positioning. Eventually it has to fix the word length and so it puts a extra 1 pixel gap between two "m"s. Looks ugly: https://bugs.documentfoundation.org/show_bug.cgi?id=88991 The thing is, so long as LibreOffice doesn't support subpixel positioning, it's not surprising that pair kerning might make these rendering issues much worse. Most kerning operations are relatively subtle, and when your renderer doesn't support subpixel positioning at all, it's not surprising that that the engine goes nuts and gives you nonsense results (like characters colliding) when asked to make small adjustment to the glyph position. If that turns out to be what's happening here, I think that's a further argument for defaulting it to off. -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
[Libreoffice-bugs] [Bug 142940] Enabling pair kerning breaks rendering of many common fonts
https://bugs.documentfoundation.org/show_bug.cgi?id=142940 Ming Hua changed: What|Removed |Added Blocks||71732 CC||ming.v@qq.com Referenced Bugs: https://bugs.documentfoundation.org/show_bug.cgi?id=71732 [Bug 71732] [META] Bugs related to text rendering, typography and font features in LO -- You are receiving this mail because: You are the assignee for the bug.___ Libreoffice-bugs mailing list Libreoffice-bugs@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-bugs
