sc/source/filter/excel/xltools.cxx | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
New commits: commit c3c0d671e1025ef4a1485dd0b2aa20b8b3a3f3af Author: Mike Kaganski <mike.kagan...@collabora.com> AuthorDate: Mon Dec 30 14:05:54 2019 +0100 Commit: Mike Kaganski <mike.kagan...@collabora.com> CommitDate: Mon Dec 30 17:43:50 2019 +0100 Document what is discovered about XclTools::GetXclDefColWidthCorrection This is based only on "reverse-engineering" of the formula, and is not necessarily correct. Change-Id: I2fa09e07e38de6c706cc6bf4ede7da4f04cb7c54 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/85994 Tested-by: Jenkins Reviewed-by: Mike Kaganski <mike.kagan...@collabora.com> diff --git a/sc/source/filter/excel/xltools.cxx b/sc/source/filter/excel/xltools.cxx index 9c94d10765c1..d8c5eb6f13c9 100644 --- a/sc/source/filter/excel/xltools.cxx +++ b/sc/source/filter/excel/xltools.cxx @@ -312,8 +312,32 @@ sal_uInt16 XclTools::GetXclColumnWidth( sal_uInt16 nScWidth, long nScCharWidth ) return limit_cast< sal_uInt16 >( fXclWidth ); } +// takes font height in twips (1/20 pt = 1/1440 in) +// returns correction value in 1/256th of *digit width* of default font double XclTools::GetXclDefColWidthCorrection( long nXclDefFontHeight ) { + // Excel uses *max digit width of default font* (W) as cell width unit. Also it has 5-pixel + // "correction" to cell widths (ECMA-376-1:2016 18.3.1.81): each cell has 1-pixel padding, then + // 3 pixels for the border (which may be 1-pixel - hairline - then it will have 2 additional + // 1-pixel spacings from each side; or e.g. 2 hairlines with 1-pixel spacing in the middle; or + // thick 3-pixel). Obviously, correction size entirely depends on pixel size (and it is actually + // different in Excel on monitors with different resolution). Thus actual (displayed/printed) + // cell widths consist of X*W+5px; stored in file is the X (or X*256 if 1/256th of digit width + // units are used) value. + // This formula apparently converts this 5-pixel correction to 1/256th of digit width units. + // Looks like it is created from + // + // 5 * 256 * 1440 * 2.1333 / (96 * max(N-15, 60)) + 50.0 + // + // where 5 - pixel correction; 256 - used to produce 1/256th of digit width; 1440 - used to + // convert font height N (in twips) to inches; 2.1333 - an (empirical?) quotient to convert + // font *height* into digit *width*; 96 - "standard" monitor resolution (DPI). + // Additionally the formula uses 15 (of unknown origin), 60 (minimal font height 3 pt), and + // 50.0 (also of unknown origin). + // + // TODO: convert this to take font digit width directly (and possibly DPI?), to avoid guessing + // the digit width and pixel size. Or DPI might stay 96, to not follow Excel dependency on DPI + // in addition to used font, and have absolute size of the correction fixed 5/96 in. return 40960.0 / ::std::max( nXclDefFontHeight - 15, 60L ) + 50.0; } _______________________________________________ Libreoffice-commits mailing list libreoffice-comm...@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/libreoffice-commits