gdef.htm

TrueType字库标准文档

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<TR><TD VALIGN=TOP>uint16</TD><TD VALIGN=TOP>CaretValueFormat</TD><TD>Format identifier-format = 2</TD></TR>
<TR><TD VALIGN=TOP>uint16</TD><TD VALIGN=TOP>CaretValuePoint</TD><TD>Contour point index on glyph</TD></TR>
</TABLE>&nbsp;&nbsp;
	
<H4>CaretValue Format 3</H4>
<P>The third format (CaretValueFormat3) also specifies the value in design units, but it uses a Device table rather than a contour point to adjust the value. This format offers the advantage of fine-tuning the Coordinate value for any device resolution. (For more information about Device tables, see the chapter, Common Table Formats.)

<P>The format consists of a format identifier (CaretValueFormat), an X or Y value (Coordinate), and an offset to a Device table (DeviceTable). 

<P>Example 6 at the end of this chapter shows a CaretValueFormat3 table.

<BR>&nbsp;<BR><FONT SIZE=5>CaretValueFormat3 table: Design units plus Device table</FONT>

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<TR><TH BGCOLOR="#C0C0C0">Type</TH><TH BGCOLOR="#C0C0C0">Name</TH><TH BGCOLOR="#C0C0C0">Description</TH></TR>
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<TR><TD VALIGN=TOP>uint16</TD><TD VALIGN=TOP>CaretValueFormat</TD><TD>Format identifier-format = 3</TD></TR>
<TR><TD VALIGN=TOP>int16</TD><TD VALIGN=TOP>Coordinate</TD><TD>X or Y value, in design units</TD></TR>
<TR><TD VALIGN=TOP>Offset</TD><TD VALIGN=TOP>DeviceTable</TD><TD>Offset to Device table for X or Y value-from beginning of CaretValue table</TD></TR>
</TABLE>&nbsp;&nbsp;

<H3>GDEF Table Examples</H3>
<P>The rest of this chapter describes examples of all the GDEF table formats. All the examples reflect unique parameters described below, but the samples provide a useful reference for building tables specific to other situations. 

<P>The examples have three columns showing hex data, source, and comments.

<H4>Example 1: GDEF Header</H4>
<P>Example 1 shows a GDEF Header definition with offsets to each of the main tables in GDEF.

<BR>&nbsp;<BR><FONT SIZE=5>Example 1</FONT>

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<TR><TH BGCOLOR="#C0C0C0">Hex Data</TH><TH BGCOLOR="#C0C0C0">Source</TH><TH BGCOLOR="#C0C0C0">Comments</TH></TR>
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<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>GDEFHeader</STRONG><BR><BR>TheGDEFHeader</TD><TD VALIGN=BOTTOM>GDEFHeader table definition</TD></TR>
<TR><TD VALIGN=TOP>00010000</TD><TD VALIGN=TOP>0x00010000</TD><TD>Version</TD></TR>
<TR><TD VALIGN=TOP>000A</TD><TD VALIGN=TOP>GlyphClassDefTable</TD><TD>offset to GlyphClassDef table</TD></TR>
<TR><TD VALIGN=TOP>0026</TD><TD VALIGN=TOP>AttachListTable</TD><TD>offset to AttachList table</TD></TR>
<TR><TD VALIGN=TOP>0040</TD><TD VALIGN=TOP>LigCaretListTable</TD><TD>offset to LigCaretList table</TD></TR>
</TABLE>&nbsp;&nbsp;

<H4>Example 2: GlyphClassDef Table</H4>
<P>The GlyphClassDef table in Example 2 specifies a glyph for the each of the glyph classes predefined in the GlyphClassDef Enumeration List. 

<BR>&nbsp;<BR><FONT SIZE=5>Example 2</FONT>

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<TR><TH BGCOLOR="#C0C0C0">Hex Data</TH><TH BGCOLOR="#C0C0C0">Source</TH><TH BGCOLOR="#C0C0C0">Comments</TH></TR>
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<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>ClassDefFormat2</STRONG><BR>GlyphClassDefTable</TD><TD VALIGN=BOTTOM>ClassDef table definition</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>ClassFormat</TD></TR>
<TR><TD VALIGN=TOP>0004</TD><TD VALIGN=TOP>4</TD><TD>ClassRangeCount<BR>ClassRangeRecord[0]</TD></TR>
<TR><TD VALIGN=TOP>0024</TD><TD VALIGN=TOP>iGlyphID</TD><TD>Start</TD></TR>
<TR><TD VALIGN=TOP>0024</TD><TD VALIGN=TOP>iGlyphID</TD><TD>End</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>Class, 1 = simple glyphs<BR>ClassRangeRecord[1]</TD></TR>
<TR><TD VALIGN=TOP>009F</TD><TD VALIGN=TOP>ffiLigGlyphID</TD><TD>Start</TD></TR>
<TR><TD VALIGN=TOP>009F</TD><TD VALIGN=TOP>ffiLigGlyphID</TD><TD>End</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>Class, 2 = ligature glyphs<BR>ClassRangeRecord[2]</TD></TR>
<TR><TD VALIGN=TOP>0058</TD><TD VALIGN=TOP>umlautAccentGlyphID</TD><TD>Start</TD></TR>
<TR><TD VALIGN=TOP>0058</TD><TD VALIGN=TOP>umlautAccentGlyphID</TD><TD>End</TD></TR>
<TR><TD VALIGN=TOP>0003</TD><TD VALIGN=TOP>3</TD><TD>Class, 3 = mark glyphs<BR>ClassRangeRecord[3]</TD></TR>
<TR><TD VALIGN=TOP>018F</TD><TD VALIGN=TOP>CurvedTailComponentGlyphID</TD><TD>Start</TD></TR>
<TR><TD VALIGN=TOP>018F</TD><TD VALIGN=TOP>CurvedTailComponentGlyphID</TD><TD>End</TD></TR>
<TR><TD VALIGN=TOP>0004</TD><TD VALIGN=TOP>4</TD><TD>Class, 4 = component glyphs</TD></TR>
</TABLE>&nbsp;&nbsp;

<H4>Example 3: AttachList Table</H4>
<P>In Example 3, the AttachList table enumerates the attachment points defined for two glyphs. The GlyphCoverage table identifies the glyphs: &quot;a&quot; and &quot;e.&quot; For each covered glyph, an AttachPoint table specifies the attachment point count and point indices: one point for the &quot;a&quot; glyph and two for the &quot;e&quot; glyph.

<BR>&nbsp;<BR><FONT SIZE=5>Example 3</FONT>

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<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>AttachList</STRONG><BR>AttachListTable</TD><TD VALIGN=BOTTOM>AttachList table definition</TD></TR>
<TR><TD VALIGN=TOP>0012</TD><TD VALIGN=TOP>GlyphCoverage</TD><TD>offset to Coverage table</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>GlyphCount</TD></TR>
<TR><TD VALIGN=TOP>0008</TD><TD VALIGN=TOP>aAttachPoint</TD><TD>AttachPoint[0]</TD></TR>
<TR><TD VALIGN=TOP>000C</TD><TD VALIGN=TOP>eAttachPoint</TD><TD>AttachPoint[1]<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>AttachPoint</STRONG><BR>aAttachPoint</TD><TD VALIGN=BOTTOM>AttachPoint table definition</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>PointCount</TD></TR>
<TR><TD VALIGN=TOP>0012</TD><TD VALIGN=TOP>18</TD><TD>PointIndex[0]<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>AttachPoint</STRONG><BR>eAttachPoint</TD><TD VALIGN=BOTTOM>AttachPoint table definition</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>PointCount</TD></TR>
<TR><TD VALIGN=TOP>000E</TD><TD VALIGN=TOP>14</TD><TD>PointIndex[0]</TD></TR>
<TR><TD VALIGN=TOP>0017</TD><TD VALIGN=TOP>23</TD><TD>PointIndex[1]<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>CoverageFormat1</STRONG><BR>GlyphCoverage</TD><TD VALIGN=BOTTOM>Coverage table definition</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>CoverageFormat</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>GlyphCount</TD></TR>
<TR><TD VALIGN=TOP>001C</TD><TD VALIGN=TOP>aGlyphID</TD><TD>GlyphArray[0]</TD></TR>
<TR><TD VALIGN=TOP>0020</TD><TD VALIGN=TOP>eGlyphID</TD><TD>GlyphArray[1]</TD></TR>
</TABLE>&nbsp;&nbsp;

<H4>Example 4: LigCaretList Table, LigGlyph Table and CaretValueFormat1 Table</H4>
<P>Example 4 defines a list of ligature carets. The LigCoverage table lists all the ligature glyphs that define caret positions. In this example, two ligatures are covered, &quot;ffi&quot; and &quot;fi.&quot; For each covered glyph, a LigGlyph table specifies the number of carets for the ligature and their coordinate values. The &quot;fi&quot; ligature defines one caret, positioned between the &quot;f&quot; and &quot;i&quot; components; the &quot;ffi&quot; ligature defines two, one positioned between the two &quot;f&quot; components and the other positioned between the &quot;f&quot; and &quot;i.&quot; The CaretValue tables shown here use Format1, where values are specified in design units only.

<BR>&nbsp;<BR><FONT SIZE=5>Example 4</FONT>

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<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>LigCaretList</STRONG><BR>LigCaretListTable</TD><TD VALIGN=BOTTOM>LigCaretList table definition</TD></TR>
<TR><TD VALIGN=TOP>0008</TD><TD VALIGN=TOP>LigCoverage</TD><TD>offset to Coverage table</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>LigGlyphCount</TD></TR>
<TR><TD VALIGN=TOP>0010</TD><TD VALIGN=TOP>fiLigGlyph</TD><TD>offset to LigGlyph table[0]</TD></TR>
<TR><TD VALIGN=TOP>0014</TD><TD VALIGN=TOP>ffiLigGlyph</TD><TD>offset to LigGlyph table[1]<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>CoverageFormat1</STRONG><BR>LigCoverage</TD><TD VALIGN=BOTTOM>Coverage table definition</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>CoverageFormat</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>GlyphCount</TD></TR>
<TR><TD VALIGN=TOP>009F</TD><TD VALIGN=TOP>ffiLigGlyphID</TD><TD>GlyphArray[0]</TD></TR>
<TR><TD VALIGN=TOP>00A5</TD><TD VALIGN=TOP>fiLigGlyphID</TD><TD>GlyphArray[1]<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>LigGlyph</STRONG><BR>fiLigGlyph</TD><TD VALIGN=BOTTOM>LigGlyph table definition</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>CaretCount, equals the number of components - 1</TD></TR>
<TR><TD VALIGN=TOP>000E</TD><TD VALIGN=TOP>CaretFI</TD><TD>CaretValue[0]<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>LigGlyph</STRONG><BR>ffiLigGlyph</TD><TD VALIGN=BOTTOM>LigGlyph table definition</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>CaretCount, equals the number of components - 1</TD></TR>
<TR><TD VALIGN=TOP>0006</TD><TD VALIGN=TOP>CaretFFI1</TD><TD>CaretValue[0]</TD></TR>
<TR><TD VALIGN=TOP>000E</TD><TD VALIGN=TOP>CaretFFI2</TD><TD>CaretValue[1]<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>CaretValueFormat1</STRONG><BR>CaretFI</TD><TD VALIGN=BOTTOM>CaretValue table definition</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>CaretValueFormat design units only</TD></TR>
<TR><TD VALIGN=TOP>025B</TD><TD VALIGN=TOP>603</TD><TD>Coordinate X or Y value<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>CaretValueFormat1</STRONG><BR>CaretFFI1</TD><TD VALIGN=BOTTOM>CaretValue table definition</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>CaretValueFormat design units only</TD></TR>
<TR><TD VALIGN=TOP>025B</TD><TD VALIGN=TOP>603</TD><TD>Coordinate X or Y value<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>CaretValueFormat1</STRONG><BR>CaretFFI2</TD><TD VALIGN=BOTTOM>CaretValue table definition</TD></TR>
<TR><TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>CaretValueFormat design units only</TD></TR>
<TR><TD VALIGN=TOP>04B6</TD><TD VALIGN=TOP>1206</TD><TD>Coordinate X or Y value</TD></TR>
</TABLE>&nbsp;&nbsp;

<H4>Example 5: CaretValueFormat2 Table</H4>
<P>Example 5 shows a CaretValueFormat2 table that specifies a ligature caret coordinate in terms of a contour point index on a specific glyph. The final position of the caret depends on the location of the contour point on the glyph after hinting.

<BR>&nbsp;<BR><FONT SIZE=5>Example 5</FONT>

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<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>CaretValueFormat2</STRONG><BR>Caret1</TD><TD VALIGN=BOTTOM>CaretValue table definition</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>CaretValueFormat contour point</TD></TR>
<TR><TD VALIGN=TOP>000D</TD><TD VALIGN=TOP>13</TD><TD>CaretValuePoint contour point index</TD></TR>
</TABLE>&nbsp;&nbsp;

<H4>Example 6: CaretValueFormat3 Table</H4>
<P>In Example 6, the CaretValueFormat3 table defines a caret position in design units, but includes a Device table to adjust the X or Y coordinate for the point size and resolution of the output font. Here, the Device table specifies pixel adjustments for font sizes from 12 ppem to 17 ppem.

<BR>&nbsp;<BR><FONT SIZE=5>Example 6</FONT>

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<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>CaretValueFormat3</STRONG><BR>Caret3</TD><TD VALIGN=BOTTOM>CaretValue table definition</TD></TR>
<TR><TD VALIGN=TOP>0003</TD><TD VALIGN=TOP>3</TD><TD>CaretValueFormat design units plus Device table</TD></TR>
<TR><TD VALIGN=TOP>04B6</TD><TD VALIGN=TOP>1206</TD><TD>Coordinate X or Y value, design units</TD></TR>
<TR><TD VALIGN=TOP>0006</TD><TD VALIGN=TOP>CaretDevice</TD><TD>offset to Device table<HR></TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>DeviceTableFormat2</STRONG><BR>CaretDevice</TD><TD VALIGN=BOTTOM>Device Table definition</TD></TR>
<TR><TD VALIGN=TOP>000C</TD><TD VALIGN=TOP>12</TD><TD>StartSize</TD></TR>
<TR><TD VALIGN=TOP>0011</TD><TD VALIGN=TOP>17</TD><TD>EndSize</TD></TR>
<TR><TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>DeltaFormat</TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>1</TD><TD>increase 12ppm by 1 pixel</TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>1</TD><TD>increase 13ppm by 1 pixel</TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>1</TD><TD>increase 14ppm by 1 pixel</TD></TR>
<TR><TD VALIGN=TOP>1111</TD><TD VALIGN=TOP>1</TD><TD>increase 15ppm by 1 pixel</TD></TR>
<TR><TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>2</TD><TD>increase 16ppm by 1 pixel</TD></TR>
<TR><TD VALIGN=TOP>2200</TD><TD VALIGN=TOP>2</TD><TD>increase 17ppm by 1 pixel</TD></TR>
</TABLE>


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Last updated 03 September 1996

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