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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.
See the section "OpenType CJK Font
Guidelines" for more information about constructing CJK (Chinese,
Japanese, and Korean) fonts.
The difference between version 1.0 and version 1.1 is the name and definition of:
- ascender becomes vertTypoAscender
- descender becomes vertTypoDescender
- lineGap becomes vertTypoLineGap
The vertical header table format follows: Vertical
Header Table
Version 1.0
| Type |
Name |
Description |
| Fixed |
version |
Version number of the vertical header
table; 0x00010000 for version 1.0 |
| SHORT |
ascent |
Distance in FUnits from the centerline to the previous line’s descent. |
| SHORT |
descent |
Distance in FUnits from the centerline 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. |
Version 1.1
| Type |
Name |
Description |
| Fixed |
version |
Version number of the vertical header
table; 0x00011000 for version 1.1
Note the representation of a non-zero fractional part, in Fixed numbers. |
| SHORT |
vertTypoAscender |
The vertical typographic ascender for this font. It is the distance in FUnits from the ideographic em-box center baseline for the vertical axis to the right of the ideographic em-box and is usually set to (head.unitsPerEm)/2. For example, a font with an em of 1000 fUnits will set this field to 500. See the baseline section of the OpenType Tag Registry for a description of the ideographic em-box. |
| SHORT |
vertTypoDescender |
The vertical typographic descender for this font. It is the distance in FUnits from the ideographic em-box center baseline for the horizontal axis to the left of the ideographic em-box and is usually set to (head.unitsPerEm)/2. For example, a font with an em of 1000 fUnits will set this field to 500. |
| SHORT |
vertTypoLineGap |
The vertical typographic gap for this font. An application can determine the recommended line spacing for single spaced vertical text for an OpenType font by the following expression: ideo embox width + vhea.vertTypoLineGap |
| 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 |
0x00011000 |
version |
Version number of the vertical header table, in fixed-point format, is 1.1 |
| 4/2 |
1024 |
vertTypoAscender |
Half the em-square height. |
| 6/2 |
-1024 |
vertTypoDescender |
Minus half the em-square height. |
| 8/2 |
0 |
vertTypoLineGap |
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 September 2002
© 2001 Microsoft Corporation. All rights reserved. Terms of use.
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