dollarchlang

Simple AutoHotKey script to switch keyboard layout when the $ key is pressed. This is particularly useful when writing (La)TeX in right-to-left languages, but when (for example) English is needed in a math environment. Currently, this script has been designed to work with TeXstudio and switches between Persian and British English.

Usage

1. Install [AutoHotKey] 1.
2. Modify the dollarchlang.ahk script as necessary.
3. Run the dollarchlang.ahk script.

Modifying the script

Unless you are using British English and Persian keyboard layouts with TeXstudio only, you will need to make changes to the script:

1. Open dollarchlang.ahk in a text editor.¹
2. Make your changes (see below).
3. Reload the script: find the AutoHotKey icon in the system tray, right-click and choose Reload This Script.

Adding support for other programs

This script has been tested with TeXstudio and it will probably also work with TeXmaker without any modifications (untested).

To make this script work with another program, say, ProgramX, you will need to identify the ahk_class of ProgramX. AutoHotKey comes with a program called AutoIt3 Window Spy which will identify the ahk_class when ProgramX is focussed. In dollarchlang.ahk, find the line

#If WinActive("ahk_class QWidget") || WinActive("ahk_class Qt5QWindowIcon")

and append || WinActive("ahk_class <new_ahk_class>"). It should now read

#If WinActive("ahk_class QWidget") || WinActive("ahk_class Qt5QWindowIcon") || WinActive("ahk_class <new_ahk_class>")

To add support for more programs, just repeat this process.

If you do not want to use TeXstudio, you may append || WinActive("ahk_class Notepad") to use Notepad for testing purposes.

Changing keyboard layouts

For general usage, there are two variables that you can change: NON_ROMAN_KEYBOARD and ROMAN_KEYBOARD which should contain the keyboard layout codes. To change these codes, update the following lines in dollarchlang.ahk with your keyboard layout code (see below):

NON_ROMAN_KEYBOARD = 0429
ROMAN_KEYBOARD = 0809

By default, these are the codes for Persian and British English, respectively. Some common codes are:

Persian:          0429
Arabic:           2401
American English: 0409
British English:  0809

Finding your keyboard layout codes

To find your own keyboard layout codes:

1. Change the line that says DEBUG_MODE := false to DEBUG_MODE := true. This turns on DEBUG_MODE.
2. Reload the script.
3. In TeXstudio (or any program you added in the above section), type a $. This will print a number, e.g. 0409. This is the keyboard code for your current keyboard layout, so change the relevant variable as appropriate.

Remember to reverse step 1 to disable DEBUG_MODE.

More than two keyboard layouts

If you have more than two keyboard layouts, typing a $ will cycle between the two selected layouts NON_ROMAN_KEYBOARD and ROMAN_KEYBOARD.

Known issues and drawbacks

• This script is just a script. It is not smart enough to detect whether you are in math mode (when writing something in (La)TeX) or not. If you wishes to write something entirely in English, French or any other language that works well in math mode, simply disable the script by exiting or pausing it.
• Using double dollars ($$) for math environments will not work. Having said that, one should not use $$ ... $$ anyway; use \[ ... \] instead. See [this question] 2 on TeX.sx.
• \[ ... \] is not supported, nor are the other math environments. This is difficult to overcome because the character \ is not recognised in the Persian keyboard layout.
• Windows-only for now :(

¹ [Notepad++] 3 is a decent text editor on Windows.