On Fri, 1 Feb 2013 22:29:56 +0530 Arvind R <arvin...@gmail.com> said:

ummm i'm just testing with slider directly... and i ONLY get change callbacks
when the user drags it around, not when code sets the value... i added tests in
rev83775. i dont get any printfs for changes unless i drag myself. the +.1 -.1
0 and 1 buttons that explicitly set the slider to these values produce no
changed callback...

? fyi - i'm testing svn here...

> Hi,
> 
> The slider emits a "changed"  signal when its internal representation
> of value really changes. It does not know whether the user dragged it
> or internal updates caused the value change. Most internal incremental
> updates when trimmed to the current resolution of the slider, do not
> cause a value change and the signal is not emitted on every "set".
> 
> This behaviour causes a 'feedback-loop' in that the "changed" signal
> from an internal update, being undifferentiated from a "user-drag",
> causes a delayed reposition command to the emotion engine. The result
> is a nice 'track-jump-repeat' which in some extreme cases, a
> 'stuck-in-a-groove' effect.
> 
> The foll. patch is a solution to this problem; and also reduces the
> frequency of slider updates. An alternate solution would be to use
> _smart_callback_del() before actually updating slider in
> elc_player.c:_update_slider(), and re-installing it back - but this
> could open the door to race conditions.
> 
> Arvind
> ---
> 
> diff -uprN a/src/lib/elc_player.c b/src/lib/elc_player.c
> --- a/src/lib/elc_player.c    2013-02-01 21:59:39.000000000 +0530
> +++ b/src/lib/elc_player.c    2013-02-01 21:59:54.000000000 +0530
> @@ -163,12 +163,35 @@ _update_slider(void *data,
>     ELM_PLAYER_DATA_GET(data, sd);
> 
>     seekable = elm_video_is_seekable_get(sd->video);
> +   if (seekable == sd->disabled)
> +    elm_object_disabled_set(sd->slider, !seekable);
> +
>     length = elm_video_play_length_get(sd->video);
> -   pos = elm_video_play_position_get(sd->video);
> 
> -   elm_object_disabled_set(sd->slider, !seekable);
> -   elm_slider_min_max_set(sd->slider, 0, length);
> -   elm_slider_value_set(sd->slider, pos);
> +   if (sd->length != length) {
> +     sd->length = length;
> +     elm_slider_min_max_set(sd->slider, 0, length);
> +   }
> +
> +   if (sd->frames < 0) {
> +     pos = elm_video_play_position_get(sd->video);
> +     if (fabs(sd->pos - pos) > 0.5) {
> +             sd->pos = pos;
> +             sd->frames = 30;
> +             elm_slider_value_set(sd->slider, pos);
> +     }
> +   }
> +}
> +
> +static void
> +_frame_decoded_cb(void *data,
> +               Evas_Object *obj __UNUSED__,
> +               void *event_info __UNUSED__)
> +{
> +   ELM_PLAYER_DATA_GET(data, sd);
> +   /* do not update slider on every frame */
> +   if (--sd->frames < 0)
> +     _update_slider(data, obj, event_info);
>  }
> 
>  static void
> @@ -176,9 +199,24 @@ _update_position(void *data,
>                   Evas_Object *obj __UNUSED__,
>                   void *event_info __UNUSED__)
>  {
> +   /*
> +    * called wnenever the value of the slider is changed.
> +     *  - irespective of user drags
> +     *    or
> +     *    internal increments larger than the slider resolution.
> +     * the 2nd case causes an inadvertent repositioning of stream
> +     * which some engines respond to (xine).
> +     * This is a feedback loop that needs to be broken.
> +     */
> +   double pos;
> +
>     ELM_PLAYER_DATA_GET(data, sd);
> 
> -   elm_video_play_position_set(sd->video, elm_slider_value_get(sd->slider));
> +   pos = elm_slider_value_get(sd->slider);
> +   if (fabs(sd->pos - pos) > 0.25) {
> +     elm_video_play_position_set(sd->video, pos);
> +     sd->pos = pos;
> +   }
>  }
> 
>  static void
> @@ -455,7 +493,7 @@ _elm_player_smart_content_set(Eo *obj, v
>     else elm_layout_signal_emit(obj, "elm,player,pause", "elm");
> 
>     evas_object_smart_callback_add(sd->emotion, "frame_decode",
> -                                  _update_slider, obj);
> +                                  _frame_decoded_cb, obj);
>     evas_object_smart_callback_add(sd->emotion, "frame_resize",
>                                    _update_slider, obj);
>     evas_object_smart_callback_add(sd->emotion, "length_change",
> @@ -495,9 +533,13 @@ _elm_player_smart_add(Eo *obj, void *_pd
>       (priv->slider, _double_to_time, _str_free);
>     elm_slider_units_format_function_set
>       (priv->slider, _double_to_time, _str_free);
> -   elm_slider_min_max_set(priv->slider, 0, 0);
> +   elm_slider_min_max_set(priv->slider, 0, 1);
>     elm_slider_value_set(priv->slider, 0);
>     elm_object_disabled_set(priv->slider, EINA_TRUE);
> +   priv->disabled = EINA_TRUE;
> +   priv->length = 0.0;
> +   priv->frames = 0;
> +   priv->pos = 0.0;
>     evas_object_size_hint_align_set(priv->slider, EVAS_HINT_FILL, 0.5);
>     evas_object_size_hint_weight_set
>       (priv->slider, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
> diff -uprN a/src/lib/elm_widget_player.h b/src/lib/elm_widget_player.h
> --- a/src/lib/elm_widget_player.h     2012-11-26 12:02:53.000000000 +0530
> +++ b/src/lib/elm_widget_player.h     2013-02-01 21:59:54.000000000 +0530
> @@ -33,6 +33,11 @@ struct _Elm_Player_Smart_Data
>     Evas_Object          *rewind;
>     Evas_Object          *stop;
>     Evas_Object          *slider;
> +
> +   Eina_Bool disabled; /* used for only-when-must changes */
> +   double            length;   /*         --- ditto ---           */
> +   short             frames;   /* used to reduce update frequency */
> +   double            pos;      /* inter-callback communication to break
> slider feedback loop */
>  };
> 
>  /**
> 
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-- 
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    ras...@rasterman.com


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