[Dev] external display programming in tizen

Boram Park boram1288.park at samsung.com
Tue Oct 7 15:01:47 GMT 2014


Currently tizen platform doesn't seem to have any programming guide for 
external display.
So I want to raise issue about how tizen platform supports external display.

Below previous mails are what I and Carsten are thinking about external 
I hope to get more scenarios and opinion about external display from you 


On 10/06/2014 07:36 PM, Carsten Haitzler wrote:
> i see you've basically taken e's model of the world here. :)
> what i think here is that it's a "leaky abstraction". it has , imho, 
> far too much detailed information in it.
> in my opinion the application has to ask for high level stuff.  or 
> let's start with simple high-level and work down when/if needed.
> my reasoning - so you plug in an external screen, you create a new 
> window and mark it for "media display". what do we do whent he screne 
> is unplugged? delete the window? move it back to the main screen? and 
> message the app? we have to figure out lifecycle on connect and 
> disconenct of vsarious monitors of various classes. what if external 
> screen reconfigures to be lower res? what if it switches between 
> fullscreen media mode and "desktop multi-window mode"... this requires 
> a lot more than the below even in the most advanced modes.
> so to keep simplicity down, we should have some high level usage 
> models first.
> 1. i want to display this like a video on a tv. when the tv is no 
> longer there please delete the window as it has no use otherwise.
> this requires events to let you know a tv-style desktop/screen exists 
> somewhere (has been created), or has been deleted. it requires 
> querying if such a tv screen exists at all at any time. it requires 
> you create a window and then attahc a property that says that that 
> window is for tv purposes. the behaviro for this window would be 
> defined to be:
> 1. it can be resized at any time (tv changes resolution).
> 2. it can be deleted any time (tv screen/desktop is disconnected by 
> the user)
> 3. the window will FILL this screen at all times in fullscreen mode
> the apple docs do bring up an intersting point i have forgotten about 
> since my amiga days back in the 1980's - overscan. there should be 
> some property that indicates if you handle overscan or not (and the 
> screen/window will be adjusted accordingly).
> note that upstream efl has stuff like requesting noblanking of a 
> screen on a per elm window basis already (and handles it for x1 - 
> nothing in wl land yet), so this is separate.
> this case should handle the cases of playback of movies/tv etc., 
> handle games on external screens etc.
> 2. i want to display this specifically as a mobile ui window OR 
> specifically as a desktop ui window.
> this would be used to indicate your app is really only destined for 
> these 2 environments (exclusively). this means that if a mobile ui 
> dekstop/screen vanishes and there is no other screen/desktop to 
> migrate the window to, and it says "i am mobile ONLY" then the widnow 
> is deleted. the same for desktop (but inverted). if you do not give 
> this hint on a window, it should be assumed your window can display on 
> either mobile or desktop ui's, and it will resized/scaled/adjusted to 
> be on either screen as the user sees fit, as they attached/disconnect 
> screens and request windows to move between them. your profile and 
> scaling factors may change etc. etc. on the fly.
> 3. i PREFER mobile or PREFER desktop mode, but will migrate if i have to.
> here an app - eg like an office app (ms office, libreoffice etc.) that 
> would want to be on a desktop for productivity, but CAN switch to 
> mobile mode if it has to. the idea here is that the moment a "desktop" 
> screen/desktop is enabled/attached, the window migrates to this 
> desktop/screen right away. when it is disconnected app migrates to the 
> "closest thing you have" - might be mobile screen. there is also the 
> other - where it wants mobiule mode, but will live with being in a 
> window if it has to on a desktop display and no mobile display is there.
> can we list more usage scenarios/models to cover. i really think we 
> should do this FIRST.
> On 10/06/2014 04:54 PM, Boram Park wrote:
>> Hello Carten
>> Currently I'm trying to find out how we.. tizen platform can support 
>> external display things easily for application developer.
>> I think strongly and technically tizen platform needs to offer this 
>> kind of guide to tizen application developers. So I and my team had 
>> discussion about this. And I want to share our proposal with you.
>> [proposal]
>> Elementary seems proper module to implement this functionality 
>> because it's most high level library to create GUI and app developers 
>> are more familiar with it than other modules.
>> Of course, other GUI toolkit, such like GTK, doesn't have this kind 
>> of functionality.
>> But I believe it must be very convenient and useful in not only 
>> mobile world but also desktop world for app developer.
>> The concept of proposal is "A developer can connect elm_win to 
>> elm_desk. Then eom_win will be shown in elm_desk which is on external 
>> display."
>> When e_desk is created and destroyed, elm_desk will be also added and 
>> removed. So it won't have any dependency with window system.
>> --- structure 
>> ------------------------------------------------------------------------------------------
>> typedef struct {
>>     int zone_id
>>     int x, y, w, h
>>     Eina_List *desks
>> } Elm_Zone
>> typedef struct {
>>     int desk_id
>>     Elm_Zone *zone
>>     char *profile  //mobile | desktop | tv | ...
>>     char *extinfo  //mirror | extended | ...
>> } Elm_Desk
>> --- connecting elm_win to elm_desk 
>> ----------------------------------------------------------
>> Elm_Zone *zone;
>> Elm_Desk *desk;
>> Eina_List *zones = elm_zone_get_info_get ()
>> EINA_LIST_FOREACH (zones, l, zone)
>> {
>>     EINA_LIST_FOREACH (zone->desktops, ll, desktop)
>>     {
>>         if (!strcmp(desktop->profile, "mobile") && 
>> !strcmp(desktop->extinfo, "mirror"))
>>         {
>>             Evas_Object *win = elm_win_add()
>>             elm_win_desk_set (win, desk)
>>             ...
>>         }
>>     }
>> }
>> ---- handling events 
>> -----------------------------------------------------------------------------
>> evas_object_smart_callback_add(win, "desk.added", _win_desk_added_cb, 
>> NULL)
>> evas_object_smart_callback_add(win, "desk.removed", 
>> _win_desk_added_cb, NULL)
>> evas_object_smart_callback_add(win, "desk.changed", 
>> _win_desk_added_cb, NULL)
>> static void
>> _win_desk_added_cb(void *data, Evas_Object *obj, void *event)
>> {
>>     Elm_Desktop_Event *ev = event;
>>     Elm_desk *desk = ev->desk;
>>     if (!strcmp(desktop->profile, "mobile") && 
>> !strcmp(desktop->extinfo, "mirror"))
>>     {
>>         Evas_Object *win = elm_win_add()
>>         elm_win_desk_set (win, desk)
>>         ...
>>     }
>> }
>> Regards
>> Boram
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Boram Park<boram1288.park at samsung.com>

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