Mac OS X: How to Create Keyboard Layout and Keybinding

Xah Lee, 2007-12-30, 2010-06-21

This page tells you how to modify Mac OS X's keybinding. You can define your own keys for cursor movement and editing commands. You can also define 【⌥ Opt+‹letter›】 key to insert your favorite set of accented letter or math symbols. (€ £ ¥ ← ↑ ↓ → 「 」 α β λ § ♠ ♣ ♥ ♦ See: Sample Unicode Characters.)

Key Config File

You need to create a file at 〔~/Library/KeyBindings/DefaultKeyBinding.dict〕. Create the “KeyBindings” dir if you don't already have it.

The 〔DefaultKeyBinding.dict〕 file is just a text file, and must be encoded in utf-8. (vast majority of text editors has options to let you chose utf-8 for save.)

The file's content should be key and action pairs, like this:

/* this is comment */
{
‹keycode1› = ‹actionCode1›;
‹keycode2› = ‹actionCode2›;
…
}

‹Keycode› is a string that represent key press.

‹actionCode› represents what to do. Actions may be inserting a character, or text, or moving the cursor to the beginning of line, or page up, or copy and pasting, etc. (The available actions are predefined in OS X)

Simple Example

Create a file at 〔~/Library/KeyBindings/DefaultKeyBinding.dict〕, and put the following content.

/* my keybindings */

{
/* insert Unicode character with Option key down*/
"~a" = ("insertText:", "\U03B1"); /* greek alpha */
"~;" = ("insertText:", "\U2665"); /* heart symbol */

/* move cursor with i j k l keys while Ctrl key down */
"^i" = ("moveUp:");
"^k" = ("moveDown:");
"^j" = ("moveLeft:");
"^l" = ("moveRight:");
}

     i
   j k l

will move the cursor.

Restart a Cocoa application and the new keybinding will take effect in that application. Only applications that uses Cocoa Text System will support this. For example, you can launch TextEdit to test your changes.

Note: the default keybinding config file used by the system is a XML file at: 〔/System/Library/Frameworks/AppKit.framework/Resources/StandardKeyBinding.dict〕. You don't have to do anything with that file. This is for your information only.

Key Syntax

You can define keys with any of ⌘ Cmd, ⌥ Opt, Ctrl, ⇧ Shift keys held down, or any combination of them, or single keys such as b, F2.

For the syntax, see: OS X Keybinding Key Syntax.

Action Code

For each key definition, you need a action code. Action can be inserting a character, a string, moving the cursor by character, word, line, or page up/down, or open file, create new file, ….

For a list of action codes you can use, see: OS X Keybinding Action Code.

Sample File and Misc

Here's a example of defining the Home/End keys to move to the beginning/end of line.

{
"\UF729" = "moveToBeginningOfLine:"; /* home key */
"\UF72B" = "moveToEndOfLine:"; /* end key */
}

Here's example file for inserting Unicode characters with the Opt key. osx_keybinding_dict_unicode_example.txt.

Here's a example of ErgoEmacs Keybinding, one for QWERTY layout and one for Dvorak Keyboard Layout:

• ErgoEmacs_keybinding_os_x_dvorak.dict.txt
• ErgoEmacs_keybinding_os_x_qwerty.dict.txt

You can look at Xcode's keybinding file at 〔/Developer/Applications/Xcode.app/Contents/Resources/PBKeyBinding.dict〕. You can view it here: osx_keybinding_xcode.dict.txt.

Emacs Keybinding

Mac OS X by default support emacs's basic keybindings. They are:

You can add more of emacs's

However, i don't recommend it. Emacs's keys is very inefficient and ergonomically painful. See: Why Emacs's Keyboard Shortcuts are Painful. If you like a efficient keybinding for text editing, you might try: ErgoEmacs Keybinding.

Problems

See: Problems of Mac OS X's Keybinding Scheme DefaultKeyBinding.dict.

References and Resources

Here are some references and related sites.

• Apple Doc. Text System Defaults and Key Bindings @ developer.apple.com…
• Apple Doc. NSResponder Class Reference @ developer.apple.com…
• Customizing the Cocoa Text System (2006-03) By Jacob Rus. @ www.hcs.harvard.edu…
• Mac OS X Key Bindings (2005-04, 2007-05) By Llew Mason. @ http://www.lsmason.com/articles/macosxkeybindings.html

• Technical Note TN2056: Installable Keyboard Layouts @ developer.apple.com…

See also: Mac OS X Keymapping Keybinding Tools.