Re: how input method editors work

FROM : Douglas Davidson
DATE : Tue Apr 05 23:01:17 2005

On Apr 5, 2005, at 1:46 PM, Daniel Child wrote:

> Now, however, I am thoroughly confused. On the one hand, some 
> people are suggesting that IMEs can only be done using Carbon. 
> (That suggestion admittedly put me in a temporary state of shock, 
> since I know nothing about Carbon and reckoned I'd been wasting my 
> time learning Cocoa.) Now, all the "NS" class methods and protocols 
> you mention seem to be in Cocoa, but you refer me to (Carbon) TSM 
> documentation.
>
> So should I write my model in Cocoa (for the linguistic data) with 
> a Carbon plugin, or is it just the opposite (Carbon base with Cocoa 
> plugin). Or am I totally off the mark? Is MVC an inappropriate 
> paradigm? And to interact with the character palette (which seems 
> to to have a very modern feel => Cocoa-based?) would you use the 
> Carbon or Cocoa API?
>


Cocoa and Carbon aren't really two entirely different things; they 
interact and work together, sharing a great deal of common 
functionality.  When you write an input method, remember that it will 
potentially run as a plugin in every application on the system, 
Carbon or Cocoa.  The way that the input method communicates with its 
host application is through a Carbon interface, TSM.  The way that 
the UI elements in the host application communicate with the input 
method is different depending on whether the app is Carbon or Cocoa; 
Cocoa views like NSTextView use NSTextInput to communicate with input 
methods, and Cocoa under the hood handles the translation between 
this and TSM.

I know of no particular reason why you shouldn't write your input 
method using Cocoa for as much of it as you choose.  There may be 
some quirks associated with displaying Cocoa windows in a Carbon 
application, that you might run into when your input method was 
loaded into a Carbon application, if your input method puts up 
windows of its own--check the documentation on Carbon-Cocoa interaction.

Douglas Davidson