[PD] [PD-dev] tkwidgets

[Jonathan Wilkes]

----- Original Message -----
> From: Martin Peach <martin.peach at sympatico.ca>
> To: Jonathan Wilkes <jancsika at yahoo.com>
> Cc: András Murányi <muranyia at gmail.com>; pd-list <pd-list at iem.at>
> Sent: Friday, August 26, 2011 2:30 PM
> Subject: Re: [PD] [PD-dev] tkwidgets
> 
> On 2011-08-26 11:31, Jonathan Wilkes wrote:
>>  It might be a good idea to list the problems with tcl/tk so we can weigh
>>  them against the difficulty of using a different GUI toolkit. The
>>  problems I see are:
>>  * difficult to implement a decent zoom function for a canvas
>>  * can't display png without the Img library (included in 8.6)
>>  * can't do alpha transparency
>> 
>>  Of the three I listed, I'm mostly interested in the first as it means
>>  that (without prior planning) it's hard to take a patch you've been
>>  working on at font size 10 and display it adequately over a projector,
>>  for example. (If there's a work around I'd like to know it.)
>> 
>>  I'd like to hear others, but I'm mostly interested in problems with
>>  tcl/tk >= 8.5 as the GUI.
>> 
> 
> * Because tcl/tk is an interpreted language it is a lot slower than a compiled 
> language: you have a script in ASCII that has to go through a processor that 
> interprets the script to call a lower-level machine that actually does the work, 
> while Qt is compiled so it does what you ask it directly, more or less.
> * tcl/tk behaves differently on the three main platforms. See the problems with 
> font sizing for instance.

You cannot guarantee the exact same font metrics across platforms, no matter 
what toolkit you use, because they depend on the font rendering engine of that 
particular platform.  I checked this out in qt documentation, and the solution 
was the same as it should be for tcl/tk: have a loop where you measure the 
width of your text at font size x and increment x until it fits the box without 
overlapping.

Other than the font, however, the vector drawings on a tk canvas are 
the same across platforms.



> 
> Martin
>