Multiple roScreen Handling (with double buffering)

Archived
1

Hey Roku Dev Community,

I’m developing a channel with multiple roScreen’s to create custom screens with animation provided by sprites. The issue I’m facing is safely passing off between roScreens. I’ve made attempts that have either resulted in

stack overflow and crashing

inconsistent screen output, randomly returning a blank screen

a complete disaster when attempting to pass off between a double buffered roScreen and another

I know this is easily achieved with template screens by waiting for

msg.isScreenClosed()

indicating the screen has safely closed, then exiting a while true loop, but a similar feature is missing for roScreen.

I have successfully handled passing between single buffered roScreens

Function Main() as void
    
    screen = CreateObject("roScreen", false) ' single buffered roScreen
    screen.Clear(&h662D9100 + 255) 'Roku Purple
    screen.SetAlphaEnable(True)
    
    port = CreateObject("roMessagePort")
    screen.SetMessagePort(port) 'send events to port
    
    catBackground = CreateObject("roBitmap", "pkg:/images/cat-1280x720.jpg")
    if type(catBackground) = "Invalid"
        print "type(catBackground) = Invalid"
    end if
    
    ' update screen
    screen.DrawObject(0, 0, catBackground)
    screen.Finish()
    'screen.Clear(&h0000FF00 + 255)    ' clear screen for new frame, colourBlue on screen will indicate error
    print "displaying cat"
    
    ' user input
    while true
        message = wait(0, port) ' get a message, if available
        if type(message) = "roUniversalControlEvent" then
            buttonAction = message.GetInt()
            'print buttonAction
            if (buttonAction = 0) then
                ' back button - close screen
                print "------ Closed ------"
                return

            else if (buttonAction = 10) then
                ' Info/Options button (*)
                print "* Button Pressed - leaving cat"
                Lion()
                print "Returned to cat"
                screen.DrawObject(0, 0, catBackground)
                screen.Finish()
            endif
        endif
    end while
End Function

Function Lion() as void
    lionBackground = CreateObject("roBitmap", "pkg:/images/lion-1280x720.jpg")
    if type(lionBackground) = "Invalid"
        print "type(lionBackground) = Invalid"
    end if
    
    screen = CreateObject("roScreen", false)
    screen.Clear(&h662D9100 + 255) 'Roku Purple
    screen.SetAlphaEnable(True)
    
    port = CreateObject("roMessagePort")
    screen.SetMessagePort(port) 'send events to port
    
    ' update screen
    screen.DrawObject(0, 0, lionBackground)
    screen.Finish()
    'screen.Clear(&hFF000000 + 255)    ' clear screen for new frame, colourRed on screen will indicate error
    print "displaying lion"
    
    ' user input
    while true
        
        message = wait(0, port) ' get a message, if available
        if type(message) = "roUniversalControlEvent" then
            buttonAction = message.GetInt()
            'print buttonAction
            if (buttonAction = 0) then
                ' back button - close screen
                print "------ Closed ------"
                return
                
            else if (buttonAction = 10) then
                ' Info/Options button (*)
                print "* Button Pressed - leaving lion, returning to main()"
'                print "screen = Invalid"
'                screen = Invalid
                exit while
                
            endif
        endif
    end while
    
End Function

However when implementing with double buffered roScreens, it adds an extra layer of complexity.

I’m looking for a way to efficiently handle the transition between multiple double buffered roScreens. Any help is greatly appreciated.

2

Not aware of any good reason to have more than one roScreen. Just assign whatever you are drawing currently to it.

3

perhaps more advanced use of bitmaps and regions could come into play, and be sent to the single screen and controlled more easily