Nyall Dawson wrote > Actually it's a bit more complex than this, because regardless of the > DPI specified for the page, the width/height have to be specified in > size in inches * 72! (i.e. there's a hardcoded 72 dpi assumption > somewhere).
Hi, I don't know how composition.xml works, but if you wonder why in PDF page the width/height have to be specified in "size in inches * 72" you will find a hint in PDF 32000-1:2008 [1] especially at paragraphs 7.7.3.3 Page Objects, Table 30 and 8.3 Coordinate Systems. "The length of a unit along both the x and y axes is set by the UserUnit entry (PDF 1.6) in the page dictionary (see Table 30). If that entry is not present or supported, the default value of 1⁄72 inch is used. This coordinate system is called default user space" "Note 2: The default for the size of the unit in default user space (1⁄72 inch) is approximately the same as a point, a unit widely used in the printing industry. It is not exactly the same, however; there is no universal definition of a point." "UserUnit: A positive number that shall give the size of default user space units, in multiples of 1⁄72 inch. The range of supported values shall be implementation-dependent. Default value: 1.0 (user space unit is 1⁄72 inch)." See also [2] and [3]. Hope this will help. Best regards. Andrea Giudiceandrea [1] https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PDF32000_2008.pdf [2] https://stackoverflow.com/a/21164534/8779560 [3] https://github.com/qgis/QGIS/issues/33465#issuecomment-644566633 -- Sent from: http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html _______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev
