1 *rileft.txt* For Vim version 7.3. Last change: 2006 Apr 24
4 VIM REFERENCE MANUAL by Avner Lottem
5 updated by Nadim Shaikli
8 Right to Left display mode for Vim *rileft*
11 These functions were originally created by Avner Lottem:
12 E-mail: alottem@iil.intel.com
15 {Vi does not have any of these commands}
18 {only available when compiled with the |+rightleft| feature}
23 Some languages such as Arabic, Farsi, Hebrew (among others) require the
24 ability to display their text from right-to-left. Files in those languages
25 are stored conventionally and the right-to-left requirement is only a
26 function of the display engine (per the Unicode specification). In
27 right-to-left oriented files the characters appear on the screen from
30 Bidirectionality (or bidi for short) is what Unicode offers as a full
31 solution to these languages. Bidi offers the user the ability to view
32 both right-to-left as well as left-to-right text properly at the same time
33 within the same window. Vim currently, due to simplicity, does not offer
34 bidi and is merely opting to present a functional means to display/enter/use
35 right-to-left languages. An older hybrid solution in which direction is
36 encoded for every character (or group of characters) are not supported either
37 as this kind of support is out of the scope of a simple addition to an
38 existing editor (and it's not sanctioned by Unicode either).
43 o Editing left-to-right files as in the original Vim, no change.
45 o Viewing and editing files in right-to-left windows. File orientation
46 is per window, so it is possible to view the same file in right-to-left
47 and left-to-right modes, simultaneously. (Useful for editing mixed files
48 in which both right-to-left and left-to-right text exist).
50 o Compatibility to the original Vim. Almost all features work in
51 right-to-left mode (see Bugs below).
53 o Backing from reverse insert mode to the correct place in the file
56 o No special terminal with right-to-left capabilities is required. The
57 right-to-left changes are completely hardware independent.
59 o Many languages use and require right-to-left support. These languages
60 can quite easily be supported given the inclusion of their required
61 keyboard mappings and some possible minor code change. Some of the
62 current supported languages include - |arabic.txt|, |farsi.txt| and
71 + 'rightleft' ('rl') sets window orientation to right-to-left.
72 + 'delcombine' ('deco'), boolean, if editing UTF-8 encoded languages,
73 allows one to remove a composing character which gets superimposed
74 on those that proceeded them (some languages require this).
75 + 'rightleftcmd' ('rlc') sets the command-line within certain modes
76 (such as search) to be utilized in right-to-left orientation as well.
78 o Typing backwards *ins-reverse*
80 In lieu of using full-fledged the 'rightleft' option, one can opt for
81 reverse insertion. When the 'revins' (reverse insert) option is set,
82 inserting happens backwards. This can be used to type right-to-left
83 text. When inserting characters the cursor is not moved and the text
84 moves rightwards. A <BS> deletes the character under the cursor.
85 CTRL-W and CTRL-U also work in the opposite direction. <BS>, CTRL-W
86 and CTRL-U do not stop at the start of insert or end of line, no matter
87 how the 'backspace' option is set.
89 There is no reverse replace mode (yet).
91 If the 'showmode' option is set, "-- REVERSE INSERT --" will be shown
92 in the status line when reverse Insert mode is active.
94 o Pasting when in a rightleft window
95 ----------------------------------
96 When cutting text with the mouse and pasting it in a rightleft window
97 the text will be reversed, because the characters come from the cut buffer
98 from the left to the right, while inserted in the file from the right to
99 the left. In order to avoid it, toggle 'revins' before pasting.
104 o Does not handle CTRL-A and CTRL-X commands (add and subtract) correctly
105 when in rightleft window.
107 o Does not support reverse insert and rightleft modes on the command-line.
108 However, functionality of the editor is not reduced, because it is
109 possible to enter mappings, abbreviations and searches typed from the
110 left to the right on the command-line.
112 o Somewhat slower in right-to-left mode, because right-to-left motion is
113 emulated inside Vim, not by the controlling terminal.
115 o When the Athena GUI is used, the bottom scrollbar works in the wrong
116 direction. This is difficult to fix.
118 o When both 'rightleft' and 'revins' are on: 'textwidth' does not work.
119 Lines do not wrap at all; you just get a single, long line.
121 o There is no full bidirectionality (bidi) support.
124 vim:tw=78:ts=8:ft=help:norl: