Unicode and Keyboards on Windows

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Unicode and Keyboards on Windows

• Michael KaplanCathy Wissink

Globalization Infrastructure and Font
Technology Windows International Microsoft
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Who is this talk geared towards?

• This is a high-level introduction to keyboards on
  Windows, assuming no prior knowledge.
• Audience
• Developers new to concept
• People who need to understand keyboards enough to
  understand how applications can work with them
• Not completely intended to be a nuts and bolts
  talk

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Keyboards are simple, right?

• Fonts
• Rendering engines
• 135 different locales on Windows
• Custom keyboard layouts
• Turns out they are not so simple!

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Keyboard Layout, defined

• A collection of data for each keystroke and shift
  state combination with a particular keyboard
  driver (DLL)
• In other words, it is not the keyboard hardware
  but the software that connects the hardware to
  the system

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Anatomy of a keystroke

• User presses a key
• Key contains a scan code
• Keyboard layout DLL maps the scan code to a
  virtual key (VK)
• OS sends the VK to the application
• If asked, the DLL maps the VK/shift state to
  characters (if they are assigned)

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(No Transcript)
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Language features

• single character keystrokes
• ligatures
• dead keys
• shift states
• SGCap
• Caps lock key

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Ligatures

• For keyboard layouts, not the same as the
  typographic/linguistic term
• A combination of 2 to 4 UTF-16 code points
  inserted by a single keystroke

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Examples of ligatures on keyboard
Tamil keyboard in the shifted state, showing
linguistic characters Sri, Ksa, and others as
ligatures
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Dead keys

• A combination of two keystrokes to insert a
  single character
• Used often in European languages for diacritics
• Called dead since the first keystroke does not
  appear to do anything
• Not intuitive to people who are not used to them

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Dead key exampleDiaeresis on the Finnish
keyboard

• Input keys
• Type (deadkey)
• Type a
• Type A
• Type o
• Type O
• ...
• Type ltspacegt

• Result
• Nothing
• ä
• Ä
• ö
• Ö
• ...
• (spacing diaeresis)

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Shift states

• Only 47-48 physical keys to work with on the
  keyboard
• Shift states expand that number by many times
• For languages with casing, usually they are cased
  variants of each other
• More shift states available (AltGr, Ctrl)

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The Greek Keyboard, shifted and unshifted
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Caps lock

• Usually intended to be a persistent Shift
  keypress (in other words, it acts like a
  typewriter caps lock)
• Generally used to get at shift state without
  having to press two keys concurrently
• Often used with cased languages
• May do nothing in languages without case, or be
  used for other purposes

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SGCap

• Advanced usage of the Caps Lock key
• Used by Swiss German, Czech, and Hebrew keyboards
• Adds two additional shift states
• Only intuitive to people who understand the
  mechanism

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APIs

• keybd_event
• MapVirtualKeyEx
• OemKeyScan
• SendInput
• ToAsciiEx
• ToUnicodeEx
• VkKeyScanEx
• The APIs allow developers to do the same mappings
  the OS does when moving between scan codes, VKs,
  and characters.

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Factors in keyboard layout creation

• National/regional standard?
• What languages need to be supported?
• Is the set of characters needed for the language
  complete?
• Focus on code points and not glyphs?
• Do all required characters exist in Unicode?
• Consistent use of features such as dead keys,
  ligatures, etc.?

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Where do IMEs fit in?

• For most languages, they dont!
• For CJK languages, even 47 keys X 8 shift states
  is not enough
• Different mechanisms and APIs are used for IME
  interaction
• More information can be found in the Platform SDK
  (http//msdn.microsoft.com/platformsdk)

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FAQs about keyboards

• Does Microsoft make these layouts up?
• How do I add every glyph for my language?
• Dont I need an IME?
• How do I replace the layout for my language if I
  do not like the one provided?
• How do I add my own keyboard layout?

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MSKLCMicrosoft Keyboard Layout Creator

• Create new keyboard layouts
• Brand new layouts
• Modified from existing keyboards
• Deploy the created keyboard layout to NT4,
  Win2000, WinXP, or Win Server 2003 machines
• Save the definition of the keyboard for later
  development

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MSKLC demos
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Other References

• This tutorial's corresponding paper
• Windows Keyboard Layoutshttp//www.microsoft.com/
  globaldev/reference/keyboards.aspx
• Nadine Kano, Developing International Software
  (out of print, but still available on the
  web)http//microsoft.com/globaldev/dis_v1/disv1.a
  sp
• New! Developing International Software , 2nd
  editionhttp//microsoft.com/globaldev/dis_v2/disv
  2.asp
• Internationalization with Visual
  Basichttp//i18nWithVB.com/
• Get on the MSKLC Beta!

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Questions?
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Don't forget to fill out your evaluations!

• Unicode and Keyboards on Windows