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sdornan's avatar
sdornan
Visitor
14 years ago

Delay Category Feed Load

I'm trying to modify the showPosterScreen() function from the video player sample in the SDK for my app.

One thing I've noticed is that Roku will fetch the feed for a focused category even when the user is only focusing on that category on his/her way to another category. For example, if the user moves from category 1 to category 6, Roku fetches the feeds for categories 2 through 5 before the content for category 6 is displayed. This has a big negative effect on my app's performance.

Is there an easy way to delay the fetching of a category feed without it affecting the responsiveness of the UI? Perhaps only fetch the category if the user remains focused on the category for a second or something?

Thanks!


Function showPosterScreen(screen As Object) As Integer

    if validateParam(screen, "roPosterScreen", "showPosterScreen") = false return -1

    m.curCategory = 0
    m.curShow = 0

    initCategoryList()
    categoryList = getCategoryList(m.Categories)
    screen.SetListNames(m.CategoryNames)
    screen.SetContentList(getShowsForCategoryItem(categoryList[m.curCategory]))
    screen.Show()

    while true
        msg = wait(0, screen.GetMessagePort())
        if type(msg) = "roPosterScreenEvent" then
            print "showPosterScreen | msg = "; msg.GetMessage() " | index = "; msg.GetIndex()
            if msg.isListFocused() then
                m.curCategory = msg.GetIndex()
                m.curShow = 0
                'get the list of shows for the currently selected item
                empty_list = CreateObject("roArray", 10, true)
                screen.SetContentList(empty_list)
                screen.ShowMessage("retrieving...")
                screen.SetContentList(getShowsForCategoryItem(categoryList[msg.GetIndex()]))
                screen.SetFocusedListItem(m.curShow)
                print "list focused | current category = "; m.curCategory
            else if msg.isListItemFocused() then
                print "list item focused | current show = "; msg.GetIndex()
            else if msg.isListItemSelected() then
                m.curShow = msg.GetIndex()
                print "list item selected | current show = "; m.curShow
                m.curShow = displayShowDetailScreen(categoryList[m.curCategory], msg.GetIndex())
                screen.setFocusedListItem(m.curShow)
            else if msg.isScreenClosed() then
                return -1
            end if
        end If
    end while

End Function
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7 Replies

  • RokuChris's avatar
    RokuChris
    Roku Employee
    14 years ago
    You probably want to move the content loading logic out of the isListFocused() handler and just set a flag there instead. Then, delay the content load till you're reasonably sure the user has stopped scrolling. viewtopic.php?f=34&t=35345
  • RokuJoel's avatar
    RokuJoel
    Binge Watcher
    14 years ago
    You can use rotimespan, executing mark() on each islistfocused() and loading content after timer.totalmilliseconds()>500 for example.

    There are other approaches, I usually just cache all data in an array so that there is no need to go to the server every time the user changes categories. Usually I ignore the is listselected() event.

    Joel
  • ionatan's avatar
    ionatan
    Roku Guru
    13 years ago
    Thanks, I will try rotimespan. I'm not sure how can be the content loaded after 500 ms, how can I make the script to wait, and just after 500 ms to load the content?!

    Why are you ignoring islistselected()? By "I usually just cache all data in an array" you mean that you are saving the feed in tmp:/ ? Thanks
  • RokuJoel's avatar
    RokuJoel
    Binge Watcher
    13 years ago
    Here's a very rough outline of both caching and delaying category load:


    function posterscreen()
    screen=creatobject("roposterscreen")
    screen.show()
    screen.setlistnames(["zero","one","two","three","four"]]
     'load all content for this screen into a cache variable:
    MycontentarrayCache=getAndParseDataFromMyWebsite()
    screen.setcontentlist(MyContentArrayCache[0])
    timer=createobject("rotimespan")
    timer.mark()
    while true
    msg=wait(1,port)
    if type(msg)="roPosterScreenEvent" then
    timer.mark() 'an event has happened, set a delay before loading data
    if msg.islistfocused() and timer.totalmilliseconds() >500 then
         ndx=msg.getindex()
         screen.setcontentlist(MycontentarrayCache[ndx]) 
    else if msg.islistselected()
         ndx=msg.getindex()
         'do nothing, although you *could* do a 
         'screen.setcontentlist here to override the timer, since this event 
         'indicates the user definitely wants to see this category
    else if msg.islistitemfocused()
         print "a list item is focused!"
    else if msg.islistitemselected()
         print "a list item is selected, do something"
    end if
    end while
    end function


    as far as caching goes, if you have five sections:

    screen.setlistnames(["zero","one","two","three","four"]]

    then you would need to load MycontentarrayCache[0] with an array containing each poster item for section zero, and MycontentarrayCache[1] with an array containing each poster item for section one, etc.

    Hope that is helpful.

    - Joel
  • ionatan's avatar
    ionatan
    Roku Guru
    13 years ago
    I tried this but timer return always 0

    I found the issue. I changed this:

    if type(msg)="roPosterScreenEvent" then
    timer.mark() 'an event has happened, set a delay before loading data
    if msg.islistfocused() and timer.totalmilliseconds() >500 then
         ndx=msg.getindex()
         screen.setcontentlist(MycontentarrayCache[ndx])
    else if msg.islistselected()


    In this


    if type(msg)="roPosterScreenEvent" then
    time_delay = timer.totalmilliseconds()
    timer.mark() 'an event has happened, set a delay before loading data
    if msg.islistfocused() and timer.time_delay  >500 then
         ndx=msg.getindex()
         screen.setcontentlist(MycontentarrayCache[ndx])
    else if msg.islistselected()