Microsoft HomeProductsSearchSupportShopWrite Us Microsoft Home

Microsoft Typography | Developer... | OpenType specification | OpenType tables | The vhea table


vhea - Vertical Header Table

The vertical header table (tag name: 'vhea') contains information needed for vertical fonts. The glyphs of vertical fonts are written either top to bottom or bottom to top. This table contains information that is general to the font as a whole. Information that pertains to specific glyphs is given in the vertical metrics table (tag name: 'vmtx') described separately. The formats of these tables are similar to those for horizontal metrics (hhea and hmtx).

Data in the vertical header table must be consistent with data that appears in the vertical metrics table. The advance height and top sidebearing values in the vertical metrics table must correspond with the maximum advance height and minimum bottom sidebearing values in the vertical header table.

The vertical header table format follows:Vertical Header Table

Type Name Description
Fixed version Version number of the vertical header
table
(0x00010000 for the initial version).
SHORT ascent Distance in FUnits from the vertical baseline to the previous line's descent.
SHORT descent Distance in FUnits from the vertical baseline to the next line's ascent.
SHORT lineGap Reserved; set to 0
SHORT advanceHeightMax The maximum advance height measurement -in FUnits found in the font. This value must be consistent with the entries in the vertical metrics table.
SHORT minTop
SideBearing
The minimum top sidebearing measurement found in the font, in FUnits. This value must be consistent with the entries in the vertical metrics table.
SHORT minBottom
SideBearing
The minimum bottom sidebearing measurement found in the font,
in FUnits.
This value must be consistent with the entries in the vertical metrics table.
SHORT yMaxExtent Defined as yMaxExtent=
minTopSideBearing+(yMax-yMin)
SHORT caretSlopeRise The value of the caretSlopeRise field divided by the value of the caretSlopeRun Field determines the slope of the caret. A value of 0 for the rise and a value of 1 for the run specifies a horizontal caret. A value of 1 for the rise and a value of 0 for the run specifies a vertical caret. Intermediate values are desirable for fonts whose glyphs are oblique or italic. For a vertical font, a horizontal caret is best.
SHORT caretSlopeRun See the caretSlopeRise field. Value=1 for nonslanted vertical fonts.
SHORT caretOffset The amount by which the highlight on a slanted glyph needs to be shifted away from the glyph in order to produce the best appearance. Set value equal to 0 for nonslanted fonts.
SHORT reserved Set to 0.
SHORT reserved Set to 0.
SHORT reserved Set to 0.
SHORT reserved Set to 0.
SHORT metricDataFormat Set to 0.
USHORT numOf
LongVerMetrics
Number of advance heights in the vertical metrics table.

Vertical Header Table Example

Offset/
length
Value Name Comment
0/4 0x00010000 version Version number of the vertical header table, in fixed-point format, is 1.0
4/2 1024 ascent Half the em-square height.
6/2 -1024 descent Minus half the em-square height.
8/2 0 lineGap Typographic line gap is 0 FUnits.
10/2 2079 advanceHeightMax The maximum advance height measurement found in the font is 2079 FUnits.
12/2 -342 minTopSideBearing The minimum top sidebearing measurement found in the font is -342 FUnits.
14/2 -333 minBottomSideBearing The minimum bottom sidebearing measurement found in the font is -333 FUnits.
16/2 2036 yMaxExtent minTopSideBearing+
(yMax-yMin)=2036.
18/2 0 caretSlopeRise The caret slope rise of 0 and a caret slope run of 1 indicate a horizontal caret for a vertical font.
20/2 1 caretSlopeRun The caret slope rise of 0 and a caret slope run of 1 indicate a horizontal caret for a vertical font.
22/2 0 caretOffset Value set to 0 for nonslanted fonts.
24/4 0 reserved Set to 0.
26/2 0 reserved Set to 0.
28/2 0 reserved Set to 0.
30/2 0 reserved Set to 0.
32/2 0 metricDataFormat Set to 0.
34/2 258 numOfLongVerMetrics Number of advance heights in the vertical metrics table is 258.



this page was last updated 26 October 1998
© 1998 Microsoft Corporation. All rights reserved. Terms of use.
comments to the MST group: ttwsite@microsoft.com

 

Microsoft Typography | Developer... | OpenType specification | OpenType tables | The vhea table