Hi Lubos, Luboš Luňák <l.lu...@collabora.com> 於 2021年4月29日 週四 上午1:19寫道：
> On Wednesday 28 of April 2021, Mark Hung wrote: > > Anyway, if you need someone to verify text layout results with vertical > > writing or > > , don't hesitate to ask. > > > > I can definitely help. I can also verify patches on Windows. > > There is also a telegram group of TDF members from the CJK area if you > > prefer. > > The Skia VCL backend code for text drawing is > SkiaSalGraphicsImpl::drawGenericLayout(). For non-vertical glyphs, the > code > is easy, just iterate over all glyphs and pass them to Skia with their > positions, possibly rotated. That approach doesn't work well for vertical > glyphs, for the tdf#103785 document I get [1], with the glyphs being > positioned too high. If I apply the attached patch that moves all vertical > glyphs down based on the glyph height, then I get [2], which appears to be > at > least roughly acceptable, although it doesn't look to be completely > correct. > > And I don't know how to make it correct. First of all, I don't know how > to > visually identify what is correct. At [3] I've uploaded screenshots of the > document rendered by LO/Cairo, LO/GDI and Word2013. They are all > different, > both in X and Y positioning. Cairo draws them slightly to the left of the > latin alphabet characters, GDI is roughly centered, Word draws them to the > right. Vertically they also differ, I made sure to include cursor in all > the > screenshots and e.g. with the first glyph (中) the cursor doesn't touch the > glyph with Word, it touches it with GDI and it overlaps the glyph with > Cairo > (the image may need zooming to see it clearly). Which of those are correct? > > To be honest, I can only verify from the point of view of a user who can read Chinese. The cursor which overlaps the position doesn't seem right. It's not a big problem as long as it does not strike through the glyph in the middle. But the inconsistence among platforms might be a problem. I would have tested fullwidth punctuations. It went wrong in vertical writing before. > Second, I would need to express the correct positioning in the code. Do > you > know how to do that? I copied the glyph-size change in the attached patch > from Cairo, it also moves in X direction by the font descent, but I'd > prefer > not to do random modifications without understanding them. > > I tried to make a patch to highlight the relative positions, and find out something that I added to fix the issue - of course it can not complete fix the problem, but it may make more sense. https://gerrit.libreoffice.org/c/core/+/114887 ( the image of the test of the patch is also attached. ) Vertical positioning there is more correct to me. It also doesn't overlap with the cursor. It introduce horizontal offset issue unfortunately. Hope that helps. > [1] https://people.collabora.com/~llunak/skia/skia_current.png > [2] https://people.collabora.com/~llunak/skia/skia_vert1.png > [3] https://people.collabora.com/~llunak/skia/ > > -- > Luboš Luňák > l.lu...@collabora.com > -- Mark Hung
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