On 8 Mar 2016, at 5:38 AM, Khaled Hosny <khaledho...@eglug.org> wrote: > > On Mon, Mar 07, 2016 at 02:04:41PM +0000, Michael Meeks wrote: >> Hi Thorsten, >> >> I missed your mail; please do maintain the CC if you want a prompt >> reply =) >> >> On Fri, 2016-03-04 at 00:43 +0100, Thorsten Behrens wrote: >> >> Hmm; the dx array as I understand it is just a simplified form of glyph >> widths; > > The DX stuff is pure madness (it is inspired by a Windows 3.1 API as I > have been told), you basically convert individual glyph advance widths > to absolute (from start of line IIRC) “character widths”; the x position > after the Nth character from the start of line, which is not so horrible > so far, except that when drawing the glyphs you take those absolute > character widths and try to convert them back to glyph > positions (that you already had but thrown away, remember) with all > sorts of bugs and rounding errors left and right (and hundreds of hacks > to work around the rounding errors).
I have to agree with this assessment. The comment in the code for ApplyDXArray (I think was this from you Khaled? I added some info to it) is interesting: // To justify a text string, Writer calls OutputDevice::GetTextArray() // to get an array that maps input characters (not glyphs) to their absolute // position, GetTextArray() in turn calls SalLayout::FillDXArray() to get an // array of character widths that it converts to absolute positions. // Writer would then apply justification adjustments to that array of absolute // character positions and return to OutputDevice, which eventually calls // ApplyDXArray(), which needs to extract the individual adjustments for each // character to apply it to corresponding glyphs, and since that information is // already lost it tries to do some heuristics to guess it again. Those // heuristics often fail, and have always been a source of all sorts of weird // text layout bugs, and instead of fixing the broken design a hack after hack // have been applied on top of it, making it a complete mess that nobody // understands. http://opengrok.libreoffice.org/xref/core/vcl/source/gdi/sallayout.cxx#901 Regardless of who wrote that comment, this is pretty insane. Chris _______________________________________________ LibreOffice mailing list LibreOffice@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice
