This should only be used in conjunction with ANSI_CHARSET. If adding new character sets to existing font, add this flag and the groups necessary to support it. No subset the VDMX group applies to all glyphs in the font. Windows will ignore any VDMX entries that are not for the ANSI subset (i.e. Windows ANSI subset the VDMX group was computed using only the glyphs required to complete the Windows ANSI character set. This is used for symbol or dingbat fonts. The currently defined values for character set are: It is recommended that VDMX version 1 be used. The semantics of bCharSet is different based on the version of the VDMX table. The bCharSet value is used to denote cases where the VDMX group was computed based on a subset of the glyphs present in the font file. Note that range checks are conceptually performed as follows: (deviceXRatio = Ratio.xRatio) & (deviceYRatio >= Ratio.yStartRatio) & (deviceYRatio <= Ratio.yEndRatio)Įach ratio grouping refers to a specific VDMX record group there must be at least 1 VDMX group in the table. If there is not a match and there is no 0,0,0 record, then there is no VDMX data for that aspect ratio. If the 0,0,0 group is encountered during the search, it is used (therefore if this group is not at the end of the ratio groupings, no group that follows it will be used). Ratios of 2:2 are the same as 1:1.Īspect ratios are matched against the target device by normalizing the entire ratio range record based on the current X resolution and performing a range check of Y resolutions for each record after normalization. Ratios are set up as follows: For a 1:1 aspect ratioĪll values set to zero signal the default grouping to use if present, this must be the last Ratio group in the table. Offset from start of this table to the VDMXGroup table for a corresponding RatioRange record. The VDMX table consists of a header followed by groupings of VDMX records. In order to avoid grid fitting the entire font to determine the correct height, the VDMX table has been defined. Because TrueType instructions can lead to Font Heights that differ from the actual scaled and rounded values, basing the Font Height strictly on the yMax and yMin can result in “lost pixels.” Windows will clip any pixels that extend above the yMax or below the yMin. Windows calls this distance the Font Height. Under Windows, the usWinAscent and usWinDescent values from the OS/2 table will be used to determine the maximum black height for a font at any given size. The VDMX table relates to OpenType™ fonts with TrueType outlines.
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