[PD-dev] canvas_* functions and using glist_getcanvas()

[Hans-Christoph Steiner]

Sounds like you are saying that calls to canvas_fixlinesfor()  
shouldn't have calls to glist_getcanvas() in them.  It seems not very  
straightforward, for example, the iemguis included in Pd-vanilla have  
this:

canvas_fixlinesfor(glist_getcanvas(x->x_gui.x_glist), (t_text*)x);

.hc

On Jul 14, 2010, at 3:15 PM, Miller Puckette wrote:

> I think glist_getcanvas() is only appropriate when getting or changing
> properties that are inherited from the containing canvas (whether  
> visible
> or not, for example) -- and many canvas_whatever(canvas, object) or
> glist_whatever(canvas, object) calls assume tha the oject is indeed  
> in that
> glist itself (glist is synonym for canvas) and will crash if not.
>
> cheers
> Miller
>
> On Wed, Jul 14, 2010 at 01:17:41PM -0400, Hans-Christoph Steiner  
> wrote:
>>
>> I've noticed that in GUI objects, its quite common to call the
>> canvas_* functions using glist_getcanvas().  I also just found out
>> that this causes a crash in [envgen] when this is done for
>> canvas_deletelinesfor().  See bug:
>>
>> http://sourceforge.net/tracker/index.php?func=detail&aid=2842897&group_id=55736&atid=478070
>>
>> So it seems to me that glist_getcanvas() should not be called on the
>> glist before sending it to one of these canvas functions.  I was
>> wondering if this is kind of a blanket rule, and we should be  
>> removing
>> the glist_getcanvas() calls in GUI objects.  For example:
>>
>> unauthorized/cooled~/cooled~.c:
>> canvas_deletelinesfor( glist_getcanvas(glist), (t_text *)z);
>> unauthorized/cooled~/cooled~.c:
>> canvas_fixlinesfor( glist_getcanvas( x->x_glist ), (t_text*)x );
>>
>> In ggee/gui/w_envgen.h, I fixed the crasher by replacing:
>>
>>    canvas_deletelinesfor(glist_getcanvas(glist), x);
>>
>> with this:
>>
>>    canvas_deletelinesfor(glist, x);
>>
>> .hc
>>
>> ----------------------------------------------------------------------------
>>
>> "Free software means you control what your computer does. Non-free
>> software means someone else controls that, and to some extent  
>> controls
>> you." - Richard M. Stallman
>>
>>
>>
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