[PD-dev] update to [cnv] help to document arguments

[Mathieu Bouchard]

On Mon, 26 Nov 2007, Hans-Christoph Steiner wrote:

> Hmmm, upon thinking about this, this makes me think that the
> tkwidgets library should include the tk canvas primitives like
> "rectangle", "arc", "polygon", "line", etc.  The idea would be a
> simple access to Tk drawing rather, which is a different mission than
> Pd's graphical data structures. You can read more the Tk canvas here:
> http://tcl.tk/man/tcl8.4/TkCmd/canvas.htm
> I would love to have collaborators to develop tkwidgets library
> completely, for example, the canvas.

If you make a generic wrapper for all tk widget constructors, that 
includes all the methods of the tk objects, then you will have support for 
this automatically, by sending a "create line ..." message to a [tkcanvas] 
pd object. Your tkwidgets library could define a single anything-method 
for all its classes at once (just like GridFlow does in its inter-language 
interface).

Generally you should pass arguments from server to client unchanged, but 
you may want to make a few exceptions, like if the creation $1 doesn't 
start with a dot, your external would consider it as a relative path and 
would prepend ".x12345678.c." only to that argument. However, supporting 
relative paths in general would require a lot more code, as various 
options of various commands take only absolute widget paths, and the 
pattern isn't regular - the constructor's $1 is just the most common case.

Just make sure you create the tk object id in the server, so that you 
don't have to pass it back to the server, which you shouldn't do anyway 
because you want to support messages sent from [loadbang] and stuff.

The more difficult part is to get the values back and figuring out what's 
the best way to handle them. Do you know how an object would be used? For 
example, [tkentry], how does it return the symbol to the server?

   a) automatically, which is then automatically output at an outlet

   b) automatically, which would then be output upon bang

   c) manually, upon bang, and the symbol is output when it arrives to the
      server (which is implicitly like [delay])

   d) manually, upon query-commands such as [$entry get 0 end] in tk; then
      a generic mechanism sends back from the client every return value of
      every command.

   e) any combination of the above, as options offered to the user

Note that a variant of (d) would have to be offered anyway for handling 
error messages. Error messages have to round-trip through the server so 
that "find again" works.

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| Mathieu Bouchard - tél:+1.514.383.3801, Montréal QC Canada