1                 How to add a new font encoding to wxWidgets
2                 ===========================================
3
4I. Introduction
5---------------
6
7 wxWidgets has built in support for a certain number of font encodings (which
8is synonymous with code sets and character sets for us here even though it is
9not exactly the same thing), look at include/wx/fontenc.h for the full list.
10This list is far from being exhaustive though and if you have enough knowledge
11about an encoding to add support for it to wxWidgets, this tech note is for
12you!
13
14 A word of warning though: this is written out of my head and is surely
15incomplete. Please correct the text here, especially if you detect problems
16when you try following it.
17
18 Also note that I completely ignore all the difficult issues of support for
19non European languages in the GUI (i.e. BiDi and text orientation support).
20
21
22II. The receipt
23---------------
24
25Suppose you want to add support for Klingon to wxWidgets. This is what you'd
26have to do:
27
281. include/wx/fontenc.h: add a new wxFONTENCODING_KLINGON enum element, if
29   possible without changing the values of the existing elements of the enum
30   and be careful to now make it equal to some other elements -- this means
31   that you have to put it before wxFONTENCODING_MAX
32
332. wxFONTENCODING_MAX must be the same as the number of elements in 3
34   (hopefully) self explanatory arrays in src/common/fmapbase.cpp:
35   a) gs_encodings
36   b) gs_encodingDescs
37   c) gs_encodingNames
38
39   You must update all of them, e.g. you'd add wxFONTENCODING_KLINGON,
40   "Klingon (Star Trek)" and "klingon" to them in this example. The latter
41   name should ideally be understandable to both Win32 and iconv as it is used
42   to convert to/from this encoding under Windows and Unix respectively.
43   Typically any reasonable name will be supported by iconv, if unsure run
44   "iconv -l" on your favourite Unix system. For the list of charsets
45   supported under Win32, look under HKEY_CLASSES_ROOT\MIME\Database\Charset
46   in regedit. Of course, being consistent with the existing encoding names
47   wouldn't hurt neither.
48
493. Normally you don't have to do anything else if you've got support for this
50   encoding under both Win32 and Unix. If you haven't, you should modify
51   wxEncodingConverter to support it (this could be useful anyhow as a
52   fallback for systems where iconv is unavailable). To do it you must:
53   a) add a new table to src/common/unictabl.inc: note that this file is auto
54      generated so you have to modify misc/unictabl script instead (probably)
55   b) possibly update EquivalentEncodings table in src/common/encconv.cpp
56      if wxFONTENCODING_KLINGON can be converted into another one
57      (losslessly only or not?)
58
594. Add a unit test (see tn0017.txt) for support of your new encoding (with
60   time we should have a wxCSConv unit test so you would just add a case to
61   it for wxFONTENCODING_KLINGON) and test everything on as many different
62   platforms as you can.
63
64
65=== EOF ===
66
67Author:  VZ
68Version: $Id: tn0018.txt 27090 2004-05-04 08:27:20Z JS $
69