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###############################
TrueType/OpenType Table Modules
###############################
This folder is a subpackage of :py:mod:`fontTools.ttLib`. Each module here is a
specialized TT/OT table converter: they can convert raw data
to Python objects and vice versa. Usually you don't need to
use the modules directly: they are imported and used
automatically when needed by :py:mod:`fontTools.ttLib`. The tables currently
supported are:
.. toctree::
:maxdepth: 1
tables/_a_n_k_r
tables/_a_v_a_r
tables/B_A_S_E_
tables/_b_s_l_n
tables/C_B_D_T_
tables/C_B_L_C_
tables/C_F_F_
tables/C_F_F__2
tables/_c_i_d_g
tables/_c_m_a_p
tables/C_O_L_R_
tables/C_P_A_L_
tables/_c_v_a_r
tables/_c_v_t
tables/D_S_I_G_
tables/E_B_D_T_
tables/E_B_L_C_
tables/F__e_a_t
tables/_f_e_a_t
tables/F_F_T_M_
tables/_f_p_g_m
tables/_f_v_a_r
tables/_g_a_s_p
tables/_g_c_i_d
tables/G_D_E_F_
tables/G__l_a_t
tables/G__l_o_c
tables/_g_l_y_f
tables/G_M_A_P_
tables/G_P_K_G_
tables/G_P_O_S_
tables/G_S_U_B_
tables/_g_v_a_r
tables/_h_d_m_x
tables/_h_e_a_d
tables/_h_h_e_a
tables/_h_m_t_x
tables/H_V_A_R_
tables/J_S_T_F_
tables/_k_e_r_n
tables/_l_c_a_r
tables/_l_o_c_a
tables/_l_t_a_g
tables/L_T_S_H_
tables/M_A_T_H_
tables/_m_a_x_p
tables/M_E_T_A_
tables/_m_e_t_a
tables/_m_o_r_t
tables/_m_o_r_x
tables/M_V_A_R_
tables/_n_a_m_e
tables/_o_p_b_d
tables/O_S_2f_2
tables/_p_o_s_t
tables/_p_r_e_p
tables/_p_r_o_p
tables/_s_b_i_x
tables/S__i_l_f
tables/S__i_l_l
tables/S_I_N_G_
tables/S_T_A_T_
tables/S_V_G_
tables/_t_r_a_k
tables/T_T_F_A_
tables/V_D_M_X_
tables/_v_h_e_a
tables/_v_m_t_x
tables/V_O_R_G_
tables/VTT_related
tables/V_V_A_R_
The Python modules representing the tables have pretty strange names: this is due to the
fact that we need to map TT table tags (which are case sensitive)
to filenames (which on Mac and Win aren't case sensitive) as well
as to Python identifiers. The latter means it can only contain
``[A-Za-z0-9_]`` and cannot start with a number.
:py:mod:`fontTools.ttLib` provides functions to expand a tag into the format used here::
>>> from fontTools import ttLib
>>> ttLib.tagToIdentifier("FOO ")
'F_O_O_'
>>> ttLib.tagToIdentifier("cvt ")
'_c_v_t'
>>> ttLib.tagToIdentifier("OS/2")
'O_S_2f_2'
>>> ttLib.tagToIdentifier("glyf")
'_g_l_y_f'
>>>
And vice versa::
>>> ttLib.identifierToTag("F_O_O_")
'FOO '
>>> ttLib.identifierToTag("_c_v_t")
'cvt '
>>> ttLib.identifierToTag("O_S_2f_2")
'OS/2'
>>> ttLib.identifierToTag("_g_l_y_f")
'glyf'
>>>
Eg. the 'glyf' table converter lives in a Python file called::
_g_l_y_f.py
The converter itself is a class, named ``table_`` + expandedtag. Eg::
class table__g_l_y_f:
etc.
Note that if you _do_ need to use such modules or classes manually,
there are two convenient API functions that let you find them by tag::
>>> ttLib.getTableModule('glyf')
<module 'ttLib.tables._g_l_y_f'>
>>> ttLib.getTableClass('glyf')
<class ttLib.tables._g_l_y_f.table__g_l_y_f at 645f400>
>>
ttProgram: TrueType bytecode assembler/disassembler
---------------------------------------------------
.. automodule:: fontTools.ttLib.tables.ttProgram
:inherited-members:
:members:
:undoc-members:
Contributing your own table convertors
--------------------------------------
To add support for a new font table that fontTools does not currently implement,
you must subclass from :py:mod:`fontTools.ttLib.tables.DefaultTable.DefaultTable`.
It provides some default behavior, as well as a constructor method (``__init__``)
that you don't need to override.
Your converter should minimally provide two methods::
class table_F_O_O_(DefaultTable.DefaultTable): # converter for table 'FOO '
def decompile(self, data, ttFont):
# 'data' is the raw table data. Unpack it into a
# Python data structure.
# 'ttFont' is a ttLib.TTfile instance, enabling you to
# refer to other tables. Do ***not*** keep a reference to
# it: it will cause a circular reference (ttFont saves
# a reference to us), and that means we'll be leaking
# memory. If you need to use it in other methods, just
# pass it around as a method argument.
def compile(self, ttFont):
# Return the raw data, as converted from the Python
# data structure.
# Again, 'ttFont' is there so you can access other tables.
# Same warning applies.
If you want to support TTX import/export as well, you need to provide two
additional methods::
def toXML(self, writer, ttFont):
# XXX
def fromXML(self, (name, attrs, content), ttFont):
# XXX
.. automodule:: fontTools.ttLib.tables
:inherited-members:
:members:
:undoc-members:
|
