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Re: [e-users] elm_player: interference of slider with playback
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From: Carsten H. (T. R. <ra...@ra...> - 2013-02-08 09:48:25
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On Fri, 1 Feb 2013 22:29:56 +0530 Arvind R <arv...@gm...> 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) ra...@ra...
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