Need help with slightly modified Scroll SDK example

I have found that a Roku 1 is a little more sensitive to memory allocation issues: you have to be careful in what order you allocate and de-allocate large bitmaps. I'm not sure that's what is going on with your code, though.

I have also found that you can only allocate/create so many bitmaps on any model before the call to create a bitmap will fail (return invalid). You probably need to do some kind of garbage collection and/or destroy your roScreen and create a new one.

Good luck!
-JT

I believe the key is invalidating the bitmap and the region before creating the new one. In your code, you're creating a new bitmap without invalidating the previous one, so the memory from the previous bitmap is still going to be in use when you try creating the new one. You should also invalidate the region before creating the new bitmap, because it will hold the reference to the previous bitmap open, resulting in the same issue.

Add the following lines immediately after your "NewFile:" label and see if it helps:

bigbm = invalid
backgroundRegion = invalid

"TheEndless" wrote:
I believe the key is invalidating the bitmap and the region before creating the new one. In your code, you're creating a new bitmap without invalidating the previous one, so the memory from the previous bitmap is still going to be in use when you try creating the new one. You should also invalidate the region before creating the new bitmap, because it will hold the reference to the previous bitmap open, resulting in the same issue.

Add the following lines immediately after your "NewFile:" label and see if it helps:

bigbm = invalid
backgroundRegion = invalid

I added those two lines of code and unfortunately it still has the same problems. Debug screen either says the bigbm create failed or or backroundRegion failed.

You probably need to do some kind of garbage collection and/or destroy your roScreen and create a new one.

What kind of statements do i need to use to do some garbage collection, just set the object to invalid? I tried something called RunGarbageCollector() but that didn't help. I'm sure there has got to be a way to do this, roSlideshow is able to go through 25+ image pages without memory error. It would have been even better if roSlideShow supported scrolling, i wouldn't need to create my own. 😄

The last time I had problems with running out of memory, I did a few experiments. It seemed that simply setting a variable to invalid didn't accomplish anything. Running the garbage collector also didn't help much. This was based on printing out the results of RunGarbageCollector(). What did seem to help was to let my roScreen go out of scope completely. Running the garbage collector after that also may have helped, but I don't remember if I tried it both ways.

What I ended up with was creating an underlying roImageCanvas in my main routine and then calling a function that created an roScreen and everything else. After I had created numerous bitmaps and at an opportune time, I'd return back to my main routine, thus allowing the roScreen to close and go out of scope, and then run the garbage collector. Then I'd call the function that created the roScreen again and recreate everything. It' not perfect. If you run my app long enough it will still run out memory. Based on the output of RunGarbageCollector() there are still things that are not getting deallocated, but I felt it was good enough and I didn't bother to try to figure out why things I wasn't using anymore weren't getting cleaned up.

I'm not saying that the roScreen is the problem since obviously anything created in the routine that created the roScreen also goes out scope when the routine returns back to main. I'm using many bitmaps and regions.

Obviously, I don't fully understand what's going on with object allocation/deallocation. That's kind of why I said, "Good luck!". If you figure out anything I'd love to hear about it.

-JT

JT, for what it's worth, my aquarium screensaver never lets the roScreen go out of scope, and it fully refreshes itself (loads all new bitmaps, 30+) every 15 minutes without issue. It does, however, ensure that all other bitmaps and regions go completely out of scope before re-loading, which is why I suggested that might be the issue. It also uses the roCompositor for most of them, so it could be that it has better memory management built into it.

TL;DR Try allocating the msg port right after allocating the roScreen and outside the loop.

This may help in keeping memory from being fragmented.

Here is the reference guide on Garbage Collection. Objects are de-allocated when they are assigned invalid; more precisely: when their reference count goes to zero. RunGarbageCollection() is only necessary to remove circular references. I also thought about setting to invalid (as TheEndless suggested) but wasn't sure in the original statement if the de-allocation occurred before the allocation or vice versa. Setting to invalid certainly removes the ambiguity.

In my experience, the order of allocations / de-allocations make a difference. I presume because of memory fragmentation. Take care to de-allocate everything you've allocated since the bitmap. In the code, you are allocating a msgport after the bitmap. And it's being allocated/de-allocated every loop.

I've tried de-allocating just about everything that can be de-allocated. I just tried to make it more simple by using an array of roRegions and it looks like it can only do 4 items before saying the bitmap 'bmImage' was unable to be created. I find that to be a bit odd that it would stop working that early into it.

UPDATED CODE:

' ******
' ****** Scroll a view around a large plane, double buffered
' ******

Library "v30/bslCore.brs"

Function IsHD()
    di = CreateObject("roDeviceInfo")
    if di.GetDisplayType() = "HDTV" then return true
    return false
End Function

sub main()
    viewComic("ext1:/Comics/Wonder Woman/Wonder Woman 002")
end sub

function viewComic(path as string)
    'Check if the screen is in HD or not.
    if IsHD()
        screen=CreateObject("roScreen", true, 1280, 720)  'try this to see zoom
    else
        screen=CreateObject("roScreen", true)
    endif
    
    
    imagefiles = matchfiles(path,"*.jpg")
    ImageIndex = 0
    
    print imagefiles.count()
    backgroundRegion = [imagefiles.count()]
    
    msgport = CreateObject("roMessagePort")
    screen.SetPort(msgport)

    for i = 0 to imagefiles.count() - 1
        print imagefiles[i]
        bmImage = invalid
        bmImage = CreateObject("roBitmap", path + "/" + imagefiles[i])
        if bmImage = invalid then
            print "bmImage is invalid"
        end if
        backgroundRegion[i]=CreateObject("roRegion", bmImage, 0, 0, screen.getwidth(), screen.getheight())
        if backgroundRegion[i] = invalid then
            print "create region failed"
        end if
    end for
        
NewFile:
    
    'Set background region to that of the image loaded in bigbm.
    'backgroundRegion=CreateObject("roRegion", bigbm, 0, 0, screen.getwidth(), screen.getheight())
    'Check if background region was unable to be loaded.

    
    'Prevent image from overscrolling.  Stops at image edges.
    backgroundRegion[ImageIndex].SetWrap(false)

    'Output image to screen.
    screen.drawobject(0, 0, backgroundRegion[ImageIndex])
    screen.SwapBuffers()
    screen.finish()
    
    movedelta = 16
    if (screen.getwidth() <= 720)
        movedelta = 8
    endif

    codes = bslUniversalControlEventCodes()

    pressedState = -1 ' If > 0, is the button currently in pressed state
    while true
	if pressedState = -1 then
	    msg=wait(0, msgport)   ' wait for a button press
	else
	    msg=wait(1, msgport)   ' wait for a button release or move in current pressedState direction 
	endif
        if type(msg)="roUniversalControlEvent" then
                keypressed = msg.GetInt()
                print "keypressed=";keypressed
                if keypressed=codes.BUTTON_UP_PRESSED then 
                        Zip(screen, backgroundRegion, 0,-movedelta)  'up button pressed
			            pressedState = codes.BUTTON_UP_PRESSED 
                else if keypressed=codes.BUTTON_DOWN_PRESSED then 
                        Zip(screen, backgroundRegion, 0,+movedelta)  ' down button pressed
			            pressedState = codes.BUTTON_DOWN_PRESSED 
			    else if keypressed=codes.BUTTON_RIGHT_PRESSED then 
                        Zip(screen, backgroundRegion, +movedelta,0)  ' right button pressed
                        pressedState = codes.BUTTON_RIGHT_PRESSED 
                else if keypressed=codes.BUTTON_LEFT_PRESSED then 
                        Zip(screen, backgroundRegion, -movedelta, 0)  ' left button pressed
                        pressedState = codes.BUTTON_LEFT_PRESSED 
                else if keypressed = 8 then
                        print "Rewind"
                        if ImageIndex = 0 then
                            'Ignore forward page request if at end of imagelist.
                        else
                            ImageIndex = ImageIndex - 1 
                            GOTO NewFile
                        end if
                else if keypressed = 9 then
                        print "Fast Forward" 
                        if ImageIndex = ImageFiles.count() then
                            'Ignore forward page request if at end of imagelist.
                        else
                            ImageIndex = ImageIndex + 1 
                            GOTO NewFile
                        end if
                else if keypressed=codes.BUTTON_BACK_PRESSED then
		                pressedState = -1
		                exit while
                else if keypressed=codes.BUTTON_UP_RELEASED or keypressed=codes.BUTTON_DOWN_RELEASED or keypressed=codes.BUTTON_RIGHT_RELEASED or keypressed=codes.BUTTON_LEFT_RELEASED then 
		                pressedState = -1
                end if
	else if msg = invalid then
                print "eventLoop timeout pressedState = "; pressedState
                print "ERROR: msg is Invalid"
                if pressedState=codes.BUTTON_UP_PRESSED then 
                        Zip(screen, backgroundRegion, 0,-movedelta)  'up button released
                else if pressedState=codes.BUTTON_DOWN_PRESSED then 
                        Zip(screen, backgroundRegion, 0,+movedelta)  ' down button released
                else if pressedState=codes.BUTTON_RIGHT_PRESSED then 
                        Zip(screen, backgroundRegion, +movedelta,0)  ' right button released
                else if pressedState=codes.BUTTON_LEFT_PRESSED then 
                        Zip(screen, backgroundRegion, -movedelta, 0)  ' left button released
		end if
        end if
    end while

end function

function Zip(screen, region, xd, yd)
    region.Offset(xd,yd,0,0)    
    screen.drawobject(0, 0, region)
    screen.SwapBuffers()
end function

I'm not sure if this would be applicable, but there was a post stating that the maximum size image that can be loaded was reduced to 2048x2048 - perhaps one of your images is larger than that?
What happens if you shuffle or randomize the images - does it always fail for you on the same number in the queue? What do the failing images have in common?

Hmm...I just looked through the dimensions of the images and they are mostly under 2000px by both height and width, even the ones the channel stops at. Also, it didn't matter which comic i was using. Both my Batman 001 comic and my Wonder Woman 002 stop after about 4 images being loaded into the array. I took out the "STOP" command in my code and the debug screen shows the for loop continues to execute but does not have valid roBitmaps after the first four.



Ignore the lower sentences, it doesn't work with random images from Google Images.
If you're curious you could try the updated code out using a folder with 10 random images found on Google Images or something. The only code that would need to be changed is the file path i hard-coded into the viewComic() call.