Upgrading to Version 2
Contents
Internally, Togl version 2 isn't very different from version 1,
and much of the C interface is the same.
The main difference is that the focus of the Togl API has changed
from being a C API to being a Tcl API.
Which means that the full power of Togl is accessible from Tcl
(the few exceptions are considered bugs).
The biggest change is how the various callback are initialized.
In version 1,
the C API Togl_Set*Func functions had to be used
to setup the callback functions before creating the Togl widget.
And once the callbacks were set for a particular Togl widget,
they could not be changed.
If more than once Togl widget was needed,
the callback functions would need to be reset before each widget creation.
In version 2,
the callbacks are configuration arguments to the widget
and can be updated like any other standard widget configuration option.
See the Tcl API for details.
Version 1 also allowed new subcommands to be added
to the togl widget command via the C API.
This was dropped for a variety of reasons:
there is no exact Tcl equivalent,
there is no standard object-oriented technique
currently in the Tcl core (8.4.13),
it is unclear how to make the API thread safe,
and the internal Tcl C API doesn't support
dynamically changing sets of subcommands.
That said, this functionality might come back, especially when
TIP #257 is implemented.
Instead, in version 2,
create a Tcl function that takes the Togl widget as an argument.
Functions written in C can get the underlying Togl structure handle
with either the Togl_GetToglFromObj
or the Togl_GetToglFromName function,
as appropriate.
This means that there are no special Togl commands, only Tcl commands.
See the C API for details.
The stereo support has been totally revamped.
Some form of stereo is available all of the time.
Tcl support for writing strings has been added.
The font C API has been revised
so that Togl_LoadBitmapFont returns a font object instead an integer
(likewise for Togl_UnloadBitmapFont).
So instead of calling glListBase and glCallLists directly,
use Togl_WriteObj or Togl_WriteChars.
The TOGL_BITMAP_* constants remain for limited backwards
source compatibility and are deprecated.
The acceptable font names are now the same as Tk_GetFont
and the Tk font command on all platforms.
