[PD-dev] adding a built-in [change] object to the built-in GUI objects

[Jonathan Wilkes]

----- Original Message -----

> From: Hans-Christoph Steiner <hans at at.or.at>
> To: "pd-dev at iem.at List" <pd-dev at iem.at>
> Cc: 
> Sent: Friday, November 30, 2012 11:20 PM
> Subject: [PD-dev] adding a built-in [change] object to the built-in GUI objects
> 
> 
> Lots of patches use the built-in GUI objects for displays, and often a fast 
> stream of events is hooked straight up to the GUI object, causing the GUI object 
> to send many pointless updates, like draw commands when the number hasn't 
> changed, or multiple draw commands per screen refresh cycle.

The multiple draw commands per screen refresh cycle seems like the more common
source of needless draw commands.

> 
> I propose to only send the GUI update commands when the relevant value has 
> changed.  I think this should apply to both the main element, like the slider 
> knob, and the label for that GUI object, since that's often used as a 
> display.  The code change is pretty simple, but I was wondering if people 
> thought there could be any problems caused by this

At the end of hslider_set, why not just check if x->x_value==(int)(100.0*g + 0.49999)
before assigning it?  If its already equal just return.

> 
> Here is the needed change, for example, for the hslider knob:
> 
> index b352fb9..88681fc 100644
> --- a/src/g_all_guis.h
> +++ b/src/g_all_guis.h
> @@ -185,6 +185,7 @@ typedef struct _hslider
>      t_iemgui x_gui;
>      int      x_pos;
>      int      x_val;
> +    int      x_prev_val;
>      int      x_center;
>      int      x_thick;
>      int      x_lin0_log1;
> index 470771a..e1a3c83 100644
> --- a/src/g_hslider.c
> +++ b/src/g_hslider.c
> @@ -33,7 +33,7 @@ static t_class *hslider_class;
> static void hslider_draw_update(t_gobj *client, t_glist *glist)
> {
>      t_hslider *x = (t_hslider *)client;
> -    if (glist_isvisible(glist))
> +    if (glist_isvisible(glist) && x->x_val != x->x_prev_val)
>      {
>          int r = text_xpix(&x->x_gui.x_obj, glist) + (x->x_val + 
> 50)/100;
>          int ypos=text_ypix(&x->x_gui.x_obj, glist);
> @@ -57,6 +57,7 @@ static void hslider_draw_update(t_gobj *client, t_glist 
> *glist)
>                  x->x_thick = 0;
>              }
>          }
> +        x->x_prev_val = x->x_val;
>      }
> }
> 
> 
> 
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