Portable Compiled Format (PCF) font is a bitmap font format originating from X11 Window System. It matches BDF format (which is text-based) closely, but instead being binary and platform-independent (as opposed to previously used SNF binary format) due to introduced features to handle different endianness and bit order.
The overall composition of the format is straightforward: it's more or less classic directory of type-offset-size pointers, pointing to what PCF format calls "tables". Each table carries a certain piece of information related to the font (metadata properties, metrics, bitmaps, mapping of glyphs to characters, etc).
This page hosts a formal specification of Portable Compiled Format (PCF) font using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
digraph {
rankdir=LR;
node [shape=plaintext];
subgraph cluster__pcf_font {
label="PcfFont";
graph[style=dotted];
pcf_font__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="magic_pos">0</TD><TD PORT="magic_size">4</TD><TD></TD><TD PORT="magic_type">magic</TD></TR>
<TR><TD PORT="num_tables_pos">4</TD><TD PORT="num_tables_size">4</TD><TD>u4le</TD><TD PORT="num_tables_type">num_tables</TD></TR>
<TR><TD PORT="tables_pos">8</TD><TD PORT="tables_size">16</TD><TD>Table</TD><TD PORT="tables_type">tables</TD></TR>
<TR><TD COLSPAN="4" PORT="tables__repeat">repeat num_tables times</TD></TR>
</TABLE>>];
subgraph cluster__table {
label="PcfFont::Table";
graph[style=dotted];
table__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="type_pos">0</TD><TD PORT="type_size">4</TD><TD>u4le→Types</TD><TD PORT="type_type">type</TD></TR>
<TR><TD PORT="format_pos">4</TD><TD PORT="format_size">4</TD><TD>Format</TD><TD PORT="format_type">format</TD></TR>
<TR><TD PORT="len_body_pos">8</TD><TD PORT="len_body_size">4</TD><TD>u4le</TD><TD PORT="len_body_type">len_body</TD></TR>
<TR><TD PORT="ofs_body_pos">12</TD><TD PORT="ofs_body_size">4</TD><TD>u4le</TD><TD PORT="ofs_body_type">ofs_body</TD></TR>
</TABLE>>];
table__inst__body [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="body_pos">ofs_body</TD><TD PORT="body_size">...</TD><TD>switch (type)</TD><TD PORT="body_type">body</TD></TR>
</TABLE>>];
table__inst__body_body_switch [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#F0F2E4">case</TD><TD BGCOLOR="#F0F2E4">type</TD></TR>
<TR><TD>:types_properties</TD><TD PORT="case0">Properties</TD></TR>
<TR><TD>:types_bdf_encodings</TD><TD PORT="case1">BdfEncodings</TD></TR>
<TR><TD>:types_swidths</TD><TD PORT="case2">Swidths</TD></TR>
<TR><TD>:types_glyph_names</TD><TD PORT="case3">GlyphNames</TD></TR>
<TR><TD>:types_bitmaps</TD><TD PORT="case4">Bitmaps</TD></TR>
</TABLE>>];
subgraph cluster__swidths {
label="PcfFont::Table::Swidths";
graph[style=dotted];
swidths__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="format_pos">0</TD><TD PORT="format_size">4</TD><TD>Format</TD><TD PORT="format_type">format</TD></TR>
<TR><TD PORT="num_glyphs_pos">4</TD><TD PORT="num_glyphs_size">4</TD><TD>u4le</TD><TD PORT="num_glyphs_type">num_glyphs</TD></TR>
<TR><TD PORT="swidths_pos">8</TD><TD PORT="swidths_size">4</TD><TD>u4le</TD><TD PORT="swidths_type">swidths</TD></TR>
<TR><TD COLSPAN="4" PORT="swidths__repeat">repeat num_glyphs times</TD></TR>
</TABLE>>];
}
subgraph cluster__properties {
label="PcfFont::Table::Properties";
graph[style=dotted];
properties__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="format_pos">0</TD><TD PORT="format_size">4</TD><TD>Format</TD><TD PORT="format_type">format</TD></TR>
<TR><TD PORT="num_props_pos">4</TD><TD PORT="num_props_size">4</TD><TD>u4le</TD><TD PORT="num_props_type">num_props</TD></TR>
<TR><TD PORT="props_pos">8</TD><TD PORT="props_size">9</TD><TD>Prop</TD><TD PORT="props_type">props</TD></TR>
<TR><TD COLSPAN="4" PORT="props__repeat">repeat num_props times</TD></TR>
<TR><TD PORT="padding_pos">...</TD><TD PORT="padding_size">((num_props & 3) == 0 ? 0 : (4 - (num_props & 3)))</TD><TD></TD><TD PORT="padding_type">padding</TD></TR>
<TR><TD PORT="len_strings_pos">...</TD><TD PORT="len_strings_size">4</TD><TD>u4le</TD><TD PORT="len_strings_type">len_strings</TD></TR>
<TR><TD PORT="strings_pos">...</TD><TD PORT="strings_size">len_strings</TD><TD>BytesWithIo</TD><TD PORT="strings_type">strings</TD></TR>
</TABLE>>];
subgraph cluster__prop {
label="PcfFont::Table::Properties::Prop";
graph[style=dotted];
prop__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="ofs_name_pos">0</TD><TD PORT="ofs_name_size">4</TD><TD>u4le</TD><TD PORT="ofs_name_type">ofs_name</TD></TR>
<TR><TD PORT="is_string_pos">4</TD><TD PORT="is_string_size">1</TD><TD>u1</TD><TD PORT="is_string_type">is_string</TD></TR>
<TR><TD PORT="value_or_ofs_value_pos">5</TD><TD PORT="value_or_ofs_value_size">4</TD><TD>u4le</TD><TD PORT="value_or_ofs_value_type">value_or_ofs_value</TD></TR>
</TABLE>>];
prop__inst__name [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="name_pos">ofs_name</TD><TD PORT="name_size">...</TD><TD>str(UTF-8)</TD><TD PORT="name_type">name</TD></TR>
</TABLE>>];
prop__inst__str_value [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="str_value_pos">value_or_ofs_value</TD><TD PORT="str_value_size">...</TD><TD>str(UTF-8)</TD><TD PORT="str_value_type">str_value</TD></TR>
</TABLE>>];
prop__inst__int_value [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>int_value</TD><TD>value_or_ofs_value</TD></TR>
</TABLE>>];
}
}
subgraph cluster__bdf_encodings {
label="PcfFont::Table::BdfEncodings";
graph[style=dotted];
bdf_encodings__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="format_pos">0</TD><TD PORT="format_size">4</TD><TD>Format</TD><TD PORT="format_type">format</TD></TR>
<TR><TD PORT="min_char_or_byte2_pos">4</TD><TD PORT="min_char_or_byte2_size">2</TD><TD>u2le</TD><TD PORT="min_char_or_byte2_type">min_char_or_byte2</TD></TR>
<TR><TD PORT="max_char_or_byte2_pos">6</TD><TD PORT="max_char_or_byte2_size">2</TD><TD>u2le</TD><TD PORT="max_char_or_byte2_type">max_char_or_byte2</TD></TR>
<TR><TD PORT="min_byte1_pos">8</TD><TD PORT="min_byte1_size">2</TD><TD>u2le</TD><TD PORT="min_byte1_type">min_byte1</TD></TR>
<TR><TD PORT="max_byte1_pos">10</TD><TD PORT="max_byte1_size">2</TD><TD>u2le</TD><TD PORT="max_byte1_type">max_byte1</TD></TR>
<TR><TD PORT="default_char_pos">12</TD><TD PORT="default_char_size">2</TD><TD>u2le</TD><TD PORT="default_char_type">default_char</TD></TR>
<TR><TD PORT="glyph_indexes_pos">14</TD><TD PORT="glyph_indexes_size">2</TD><TD>u2le</TD><TD PORT="glyph_indexes_type">glyph_indexes</TD></TR>
<TR><TD COLSPAN="4" PORT="glyph_indexes__repeat">repeat (((max_char_or_byte2 - min_char_or_byte2) + 1) * ((max_byte1 - min_byte1) + 1)) times</TD></TR>
</TABLE>>];
}
subgraph cluster__glyph_names {
label="PcfFont::Table::GlyphNames";
graph[style=dotted];
glyph_names__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="format_pos">0</TD><TD PORT="format_size">4</TD><TD>Format</TD><TD PORT="format_type">format</TD></TR>
<TR><TD PORT="num_glyphs_pos">4</TD><TD PORT="num_glyphs_size">4</TD><TD>u4le</TD><TD PORT="num_glyphs_type">num_glyphs</TD></TR>
<TR><TD PORT="names_pos">8</TD><TD PORT="names_size">4</TD><TD>StringRef</TD><TD PORT="names_type">names</TD></TR>
<TR><TD COLSPAN="4" PORT="names__repeat">repeat num_glyphs times</TD></TR>
<TR><TD PORT="len_strings_pos">...</TD><TD PORT="len_strings_size">4</TD><TD>u4le</TD><TD PORT="len_strings_type">len_strings</TD></TR>
<TR><TD PORT="strings_pos">...</TD><TD PORT="strings_size">len_strings</TD><TD>BytesWithIo</TD><TD PORT="strings_type">strings</TD></TR>
</TABLE>>];
subgraph cluster__string_ref {
label="PcfFont::Table::GlyphNames::StringRef";
graph[style=dotted];
string_ref__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="ofs_string_pos">0</TD><TD PORT="ofs_string_size">4</TD><TD>u4le</TD><TD PORT="ofs_string_type">ofs_string</TD></TR>
</TABLE>>];
string_ref__inst__value [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="value_pos">ofs_string</TD><TD PORT="value_size">...</TD><TD>str(UTF-8)</TD><TD PORT="value_type">value</TD></TR>
</TABLE>>];
}
}
subgraph cluster__bitmaps {
label="PcfFont::Table::Bitmaps";
graph[style=dotted];
bitmaps__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="format_pos">0</TD><TD PORT="format_size">4</TD><TD>Format</TD><TD PORT="format_type">format</TD></TR>
<TR><TD PORT="num_glyphs_pos">4</TD><TD PORT="num_glyphs_size">4</TD><TD>u4le</TD><TD PORT="num_glyphs_type">num_glyphs</TD></TR>
<TR><TD PORT="offsets_pos">8</TD><TD PORT="offsets_size">4</TD><TD>u4le</TD><TD PORT="offsets_type">offsets</TD></TR>
<TR><TD COLSPAN="4" PORT="offsets__repeat">repeat num_glyphs times</TD></TR>
<TR><TD PORT="bitmap_sizes_pos">...</TD><TD PORT="bitmap_sizes_size">4</TD><TD>u4le</TD><TD PORT="bitmap_sizes_type">bitmap_sizes</TD></TR>
<TR><TD COLSPAN="4" PORT="bitmap_sizes__repeat">repeat 4 times</TD></TR>
</TABLE>>];
}
}
subgraph cluster__format {
label="PcfFont::Format";
graph[style=dotted];
format__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="padding1_pos">0</TD><TD PORT="padding1_size">2b</TD><TD>b2</TD><TD PORT="padding1_type">padding1</TD></TR>
<TR><TD PORT="scan_unit_mask_pos">0:2</TD><TD PORT="scan_unit_mask_size">2b</TD><TD>b2</TD><TD PORT="scan_unit_mask_type">scan_unit_mask</TD></TR>
<TR><TD PORT="is_most_significant_bit_first_pos">0:4</TD><TD PORT="is_most_significant_bit_first_size">1b</TD><TD>BitsType1(BigBitEndian)</TD><TD PORT="is_most_significant_bit_first_type">is_most_significant_bit_first</TD></TR>
<TR><TD PORT="is_big_endian_pos">0:5</TD><TD PORT="is_big_endian_size">1b</TD><TD>BitsType1(BigBitEndian)</TD><TD PORT="is_big_endian_type">is_big_endian</TD></TR>
<TR><TD PORT="glyph_pad_mask_pos">0:6</TD><TD PORT="glyph_pad_mask_size">2b</TD><TD>b2</TD><TD PORT="glyph_pad_mask_type">glyph_pad_mask</TD></TR>
<TR><TD PORT="format_pos">1</TD><TD PORT="format_size">1</TD><TD>u1</TD><TD PORT="format_type">format</TD></TR>
<TR><TD PORT="padding_pos">2</TD><TD PORT="padding_size">2</TD><TD>u2le</TD><TD PORT="padding_type">padding</TD></TR>
</TABLE>>];
}
}
pcf_font__seq:tables_type -> table__seq [style=bold];
pcf_font__seq:num_tables_type -> pcf_font__seq:tables__repeat [color="#404040"];
table__seq:format_type -> format__seq [style=bold];
table__seq:ofs_body_type -> table__inst__body:body_pos [color="#404040"];
table__inst__body:body_type -> table__inst__body_body_switch [style=bold];
table__inst__body_body_switch:case0 -> properties__seq [style=bold];
table__inst__body_body_switch:case1 -> bdf_encodings__seq [style=bold];
table__inst__body_body_switch:case2 -> swidths__seq [style=bold];
table__inst__body_body_switch:case3 -> glyph_names__seq [style=bold];
table__inst__body_body_switch:case4 -> bitmaps__seq [style=bold];
table__seq:type_type -> table__inst__body:body_type [color="#404040"];
swidths__seq:format_type -> format__seq [style=bold];
swidths__seq:num_glyphs_type -> swidths__seq:swidths__repeat [color="#404040"];
properties__seq:format_type -> format__seq [style=bold];
properties__seq:props_type -> prop__seq [style=bold];
properties__seq:num_props_type -> properties__seq:props__repeat [color="#404040"];
properties__seq:num_props_type -> properties__seq:padding_size [color="#404040"];
properties__seq:num_props_type -> properties__seq:padding_size [color="#404040"];
properties__seq:len_strings_type -> properties__seq:strings_size [color="#404040"];
properties__seq:strings_type -> bytes_with_io__seq [style=bold];
prop__seq:ofs_name_type -> prop__inst__name:name_pos [color="#404040"];
prop__seq:value_or_ofs_value_type -> prop__inst__str_value:str_value_pos [color="#404040"];
prop__seq:value_or_ofs_value_type -> prop__inst__int_value [color="#404040"];
bdf_encodings__seq:format_type -> format__seq [style=bold];
bdf_encodings__seq:max_char_or_byte2_type -> bdf_encodings__seq:glyph_indexes__repeat [color="#404040"];
bdf_encodings__seq:min_char_or_byte2_type -> bdf_encodings__seq:glyph_indexes__repeat [color="#404040"];
bdf_encodings__seq:max_byte1_type -> bdf_encodings__seq:glyph_indexes__repeat [color="#404040"];
bdf_encodings__seq:min_byte1_type -> bdf_encodings__seq:glyph_indexes__repeat [color="#404040"];
glyph_names__seq:format_type -> format__seq [style=bold];
glyph_names__seq:names_type -> string_ref__seq [style=bold];
glyph_names__seq:num_glyphs_type -> glyph_names__seq:names__repeat [color="#404040"];
glyph_names__seq:len_strings_type -> glyph_names__seq:strings_size [color="#404040"];
glyph_names__seq:strings_type -> bytes_with_io__seq [style=bold];
string_ref__seq:ofs_string_type -> string_ref__inst__value:value_pos [color="#404040"];
bitmaps__seq:format_type -> format__seq [style=bold];
bitmaps__seq:num_glyphs_type -> bitmaps__seq:offsets__repeat [color="#404040"];
}