base.htm

TrueType字库标准文档

<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>BaseCoordFormat design units only</TD></TR>
<TR>
<TD VALIGN=TOP>06D8</TD><TD VALIGN=TOP>1752</TD><TD>Coordinate Y value, in design units increased Max extent beyond default Cyrillic script and Russian language max extents</TD></TR>
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<H4>Example 4B: Min/Max Extents For Cyrillic Script and Russian Feature</H4>
<P>A particular language system does not need to define min/max extent coordinates if its extents match the default extents defined for the script. However, an obscure or infrequently used feature within the language system may require feature-specific extent values for proper rendering. 

<P>Example 4B shows the MinMax and FeatMinMaxRecord table definitions for this situation. The example also includes a BaseScript table, but not a BaseValues tables since it is not relevant in this example. The example shows horizontal text layout extents for the Cyrillic script and feature-specific extents for one feature in the Russian language system. Much of the data is repeated from Example 4A and modified here for comparison. 

<P>The BaseScript table includes a DefaultMinMax table for the Cyrillic script and a BaseLangSysRecord that defines a BaseLangSysTag and an offset to a MinMax table for the Russian language. The MinMax table includes a FeatMinMaxRecord and specifies a FeatMinMaxCount, but both the MinCoord and MaxCoord offsets in the MinMax table are set to NULL since no language-specific extent values are defined for Russian. The FeatMinMaxRecord defines the min/max coordinates for the Russian feature and specifies the correct FeatureTableTag.

<BR>&nbsp;<BR><FONT SIZE=5>Example 4B</font>
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<TH BGCOLOR="#C0C0C0">Hex Data</TH><TH BGCOLOR="#C0C0C0">Source</TH><TH BGCOLOR="#C0C0C0">Comments</TH></TR>
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<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseScript</STRONG><BR>HorizCyrillicBaseScriptTable</TD><TD VALIGN=BOTTOM>BaseScript table definition Cyrillic script</TD></TR>
<TR>
<TD VALIGN=TOP>0000</TD><TD VALIGN=TOP>NULL</TD><TD>offset to BaseValues table</TD></TR>
<TR>
<TD VALIGN=TOP>000C</TD><TD VALIGN=TOP>HorizCyrillicDefaultMinMaxTable</TD><TD>offset to DefaultMinMax table for default script extents</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>BaseLangSysCount<BR>BaseLangSysRecord[0] for Russian feature-specific-extents</TD></TR>
<TR>
<TD VALIGN=TOP>52555320</TD><TD VALIGN=TOP>&quot;RUS &quot;</TD><TD>BaseLangSysTag = Russian</TD></TR>
<TR>
<TD VALIGN=TOP>001A</TD><TD VALIGN=TOP>HorizRussianMinMaxTable</TD><TD>offset to MinMax table for feature-specific extents<HR></TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>MinMax</STRONG><BR>HorizCyrillicDefaultMinMaxTable</TD><TD VALIGN=BOTTOM>DefaultMinMax table definition Cyrillic script</TD></TR>
<TR>
<TD VALIGN=TOP>0006</TD><TD VALIGN=TOP>HorizCyrillicMinCoordTable</TD><TD>MinCoord offset to BaseCoord table</TD></TR>
<TR>
<TD VALIGN=TOP>000A</TD><TD VALIGN=TOP>HorizCyrillicMaxCoordTable</TD><TD>MaxCoord offset to BaseCoord table</TD></TR>
<TR>
<TD VALIGN=TOP>0000</TD><TD VALIGN=TOP>0</TD><TD>FeatMinMaxCount, no default feature extents<BR>FeatMinMaxRecord[], no FeatMinMaxRecords</TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseCoordFormat1</STRONG><BR>HorizCyrillicMinCoordTable</TD><TD>BaseCoord table definition default Cyrillic Min     extent coordinate</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>BaseCoordFormat design units only</TD></TR>
<TR>
<TD VALIGN=TOP>FF38</TD><TD VALIGN=TOP>-200</TD><TD>Coordinate Y value, in design units<HR></TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseCoordFormat1</STRONG><BR>HorizCyrillicMaxCoordTable</TD><TD VALIGN=BOTTOM>BaseCoord table definition default Cyrillic Min 	    extent coordinate</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>BaseCoordFormat design units only</TD></TR>
<TR>
<TD VALIGN=TOP>0674</TD><TD VALIGN=TOP>1652</TD><TD>Coordinate Y value, in design units<HR></TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>MinMax</STRONG><BR>HorizRussianMinMaxTable</TD><TD VALIGN=BOTTOM>MinMax table definition for Russian feature no extent differences for 
Russian language itself</TD></TR>
<TR>
<TD VALIGN=TOP>0000</TD><TD VALIGN=TOP>NULL</TD><TD>offset to Min BaseCoord table not defined, matches default</TD></TR>
<TR>
<TD VALIGN=TOP>0000</TD><TD VALIGN=TOP>NULL</TD><TD>offset to Max BaseCoord table not defined, matches default</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>FeatMinMaxCount, FeatMinMaxRecord[0] in alphabetical order</TD></TR>
<TR>
<TD VALIGN=TOP>696E7467</TD><TD VALIGN=TOP>&quot;intg&quot;</TD><TD>FeatureTableTag integral math sign Feature must be same as Tag in FeatureList</TD></TR>
<TR>
<TD VALIGN=TOP>000E</TD><TD VALIGN=TOP>HorizRussianFeatureMinCoordTable</TD><TD>MinCoord offset to BaseCoord table</TD></TR>
<TR>
<TD VALIGN=TOP>0012</TD><TD VALIGN=TOP>HorizRussianFeatureMaxCoordTable</TD><TD>MaxCoord offset to BaseCoord table<HR></TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseCoordFormat1</STRONG><BR>HorizRussianFeatureMinCoordTable</TD><TD VALIGN=BOTTOM>BaseCoord table definition Russian Feature Min extent coordinate</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>BaseCoordFormat, design units only</TD></TR>
<TR>
<TD VALIGN=TOP>FED8</TD><TD VALIGN=TOP>-296</TD><TD>Coordinate Y value, in design units increased Min extent beyond default Cyrillic Min extent</TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseCoordFormat1</STRONG><BR>HorizRussianFeatureMaxCoordTable</TD><TD VALIGN=BOTTOM>BaseCoord table definition, Russian feature Max extent 
coordinate</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>BaseCoordFormat design units only</TD></TR>
<TR>
<TD VALIGN=TOP>06D8</TD><TD VALIGN=TOP>1752</TD><TD>Coordinate Y value, in design units, increased Max extent beyond default Cyrillic Max extent</TD></TR>
</TABLE>
&nbsp;&nbsp;


<H4>Example 5: BaseCoordFormat1 Table</H4>
<P>Example 5 illustrates BaseCoordFormat1, which specifies single coordinate values in design units only. The font uses 2,048 design units/em. The example defines the default minimum extent coordinate for a math script.

<BR>&nbsp;<BR><FONT SIZE=5>Example 5</font>
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<TH BGCOLOR="#C0C0C0">Hex Data</TH><TH BGCOLOR="#C0C0C0">Source</TH><TH BGCOLOR="#C0C0C0">Comments</TH></TR>
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<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseCoordFormat1</STRONG><BR>HorizMathMinCoordTable</TD><TD VALIGN=BOTTOM>Definition of BaseCoord table for Math Min coordinate</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>BaseCoordFormat, design units only</TD></TR>
<TR>
<TD VALIGN=TOP>FEE8</TD><TD VALIGN=TOP>-280</TD><TD>Coordinate Y value, in design units</TD></TR>
</TABLE>
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<H4>Example 6: BaseCoordFormat2 Table</H4>
<P>Example 6 illustrates the BaseCoord Format 2. Like Example 5, it specifies the minimum extent coordinate for a math script. With this format, the coordinate value depends on the final position of a specific contour point on one glyph, the integral math symbol, after hinting. Again, the value is in design units (2,048 units/em).

<BR>&nbsp;<BR><FONT SIZE=5>Example 6</font>
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<TH BGCOLOR="#C0C0C0">Hex Data</TH><TH BGCOLOR="#C0C0C0">Source</TH><TH BGCOLOR="#C0C0C0">Comments</TH></TR>
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<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseCoordFormat2</STRONG><BR>HorizMathMinCoordTable</TD><TD VALIGN=BOTTOM>BaseCoord table definition for Math Min coordinate</TD></TR>
<TR>
<TD VALIGN=TOP>0002</TD><TD VALIGN=TOP>2</TD><TD>BaseCoordFormat design units plus contour point</TD></TR>
<TR>
<TD VALIGN=TOP>FEE8</TD><TD VALIGN=TOP>-280</TD><TD>Coordinate Y value, in design units</TD></TR>
<TR>
<TD VALIGN=TOP>0128</TD><TD VALIGN=TOP>IntegralSignGlyphID</TD><TD>ReferenceGlyph math integral sign</TD></TR>
<TR>
<TD VALIGN=TOP>0043</TD><TD VALIGN=TOP>67</TD><TD>BaseCoordPoint glyph contour point index</TD></TR>
</TABLE>
&nbsp;&nbsp;


<H4>Example 7: BaseCoordFormat3 Table</H4>
<P>Example 7 illustrates the BaseCoord Format 3. Like Examples 5 and 6, it specifies the minimum extent coordinate for a math script in design units (2,048 units/em). This format, however, uses a Device table to modify the coordinate value for the point size and resolution of the output font. Here, the Device table defines pixel adjustments for font sizes from 11 ppem to 15 ppem. The adjustments add one pixel at each size.

<BR>&nbsp;<BR><FONT SIZE=5>Example 7</font>
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<TH BGCOLOR="#C0C0C0">Hex Data</TH><TH BGCOLOR="#C0C0C0">Source</TH><TH BGCOLOR="#C0C0C0">Comments</TH></TR>
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<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>BaseCoordFormat3</STRONG><BR>HorizMathMinCoordTable</TD><TD VALIGN=BOTTOM>BaseCoord table definition for Math Min coordinate</TD></TR>
<TR>
<TD VALIGN=TOP>0003</TD><TD VALIGN=TOP>3</TD><TD>BaseCoordFormat design units plus device table</TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>-280</TD><TD>Coordinate Y value, in design units</TD></TR>
<TR>
<TD VALIGN=TOP>000C</TD><TD VALIGN=TOP>HorizMathMinCoordDeviceTable</TD><TD>Offset to Device table<HR></TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP><STRONG>DeviceTableFormat1</STRONG><BR>HorizMathMinCoordDeviceTable</TD><TD VALIGN=BOTTOM>Device table definition for MinCoord</TD></TR>
<TR>
<TD VALIGN=TOP>000B</TD><TD VALIGN=TOP>11</TD><TD>StartSize -11 ppem</TD></TR>
<TR>
<TD VALIGN=TOP>000F</TD><TD VALIGN=TOP>15</TD><TD>EndSize -15 ppem</TD></TR>
<TR>
<TD VALIGN=TOP>0001</TD><TD VALIGN=TOP>1</TD><TD>DeltaFormat signed 2 bit value, 8 values per uint16</TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>1</TD><TD>Increase 11ppem by 1 pixel</TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>1</TD><TD>Increase 12ppem by 1 pixel</TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>1</TD><TD>Increase 13ppem by 1 pixel</TD></TR>
<TR>
<TD VALIGN=TOP>&nbsp;</TD><TD VALIGN=TOP>1</TD><TD>Increase 14ppem by 1 pixel</TD></TR>
<TR>
<TD VALIGN=TOP>5540</TD><TD VALIGN=TOP>1</TD><TD>Increase 15ppem by 1 pixel</TD></TR>
</TABLE>

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Last updated 05 September 1996

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