It has become apparent that I will need to use roScreen in my program instead of roImageCanvas in order to speed up my program. My program makes heavy use of roImageCanvas, specifically the setLayer, clearLayer and swapLayer, in addition to the ability to setLayer something on an already occupied layer to overwrite what is already on that layer. I was wondering if there was a way for roScreen to reproduce any/all of these effects, and how I should go about changing my program to use roScreen, since I have never used it before.

Probably the biggest thing to realize is that if you double buffer the screen, you will have to redraw every object, every time. This will result in good clean movement if you optimize any calculations outside of the redraw loop. Double buffering is recommended so that you do not see "screen tears" during redraw, which happens when a draw occurs partially in two different frame refresh periods.You will most likely have a similar wait() loop that checks for universal event type that differentiates press and release. If you must have faster speed, then search the forums on the wait / sleep bug on Roku 2 devices that cause an extra 15-20ms delay. It's possible to get rid of that delay by using timers and polling message port(s) in a tight loop.I hope that helps!

It helps somewhat. Is there anywhere can I find a very simple example of a program using roScreen for reference?

The 3.0 SDK has a sample roScreen app called "Snake"

DrawRect() takes 5 arguments, not 4, the fifth being the color you want your rect to be. http://sdkdocs.roku.com/display/RokuSDK ... ntegerrgba

I threw together a little demo last night for you:you can download it here: https://www.box.com/shared/93202d2c60d4bf2effd1 In terms of the SDK examples, check out BS2Dtest and simple2d for some more ideas of what you can do, including collision detection, scaling etc. There aren't yet any examples of integrating 2DAPIs with video playback, but we should have some soon.The action takes place in the while loops:'lets say you have a set of images you want to draw as layers. You would draw them to the screen in the order in which they should appear, and you would keep redrawing them as often as possible:sub main()screen=createobject("roscreen",true)screen.setalphaenable(false)image1=createobject("robitmap","pkg:/images/imageone.png")image2=createobject("robitmap","pkg:/images/imagetwo.png")image3=createobject("robitmap","pkg:/images/imagethree.png")'lets set up some positions for these images:obj1={posx:200,posy:200}obj2={posx:400,posy:400}obj3={posx:600,posy:600}timer=createobject("rotimespan")timer.mark()while timer.totalseconds() <15 'exit this loop after 15 seconds. screen.clear(&h000000FF) 'clear screen to blackscreen.setalphaenable(false) 'disable alpha for this draw, since the object is not transparentscreen.drawobject(obj1.posx,obj1.posy,image1)screen.setalphaenable(true) 're enable for transparent imagesscreen.drawobject(obj2.posx,obj2.posy,image2)screen.drawobject(obj3.posx,obj3.posy,image3)screen.setalphaenable(false)screen.swapbuffers() 'display the completed draw on screen'move objectsif obj1.posx > 0 then obj1.posx=obj1.posx-1if obj1.posy > 0 then obj1.posy=obj1.posy-1if obj2.posx > 0 then obj2.posx=obj2.posx-1if obj2.posy > 0 then obj2.posy=obj2.posy-1if obj3.posx > 0 then obj3.posx=obj3.posx-1if obj3.posy > 0 then obj3.posy=obj3.posy-1end while'If one of the layers has transparancy, and you want the layer below to show through the transparant section, you would enable transprancy for that image when drawing to the screen.'Another approach with roScreen is to create Sprites, which are images designed to be moved around the screen, typically as objects in a game, but they can be used for almost anything.'lets create some sprites. first we need to create a compositor:compositor=createobject("rocompositor")'now we need to tell it where to draw and the background color:compositor.setdrawto(screen,&h000000FF)'To create a sprite, first we create a bitmap image, as we did beforebmp1=createobject("roBitmap", "pkg:/images/alien1.png")'then we create a region from that bitmap:reg1=createobject("roregion", bmp1,0,0,bmp1.getwidth(),bmp1.getheight())bmp2=createobject("roBitmap", "pkg:/images/alien2.png")reg2=createobject("roregion", bmp2,0,0,bmp2.getwidth(),bmp2.getheight())bmp3=createobject("roBitmap", "pkg:/images/alien3.png")reg3=createobject("roregion", bmp3,0,0,bmp3.getwidth(),bmp3.getheight())'from those three regions, we will create our sprites:spr1=compositor.newsprite(200,200,reg1,0) 'create a sprite on layer 0spr2=compositor.newsprite(250,250,reg2,1) 'create a sprite on layer 1spr3=compositor.newsprite(350,350,reg3,2) 'create a sprite on layer 3'to make it easier to work with them, we are going to put them into an array:sprArr=[spr1,spr2,spr3]'we can actually store data inside a sprite! lets put our x and y positions into an Associative Array and store in our sprite:for each sprite in sprarrsprite.setdata({xpos:sprite.getx(),ypos:sprite.gety()})end for'Ok, now lets make a little routine that moves them randomly around the screen:bounds={}bounds.x=screen.getwidth()bounds.y=screen.getheight()screen.setalphaenable(true) 'enable transparency'Lets set up a timer to control movement:movetimer=createobject("rotimespan")movetimer.mark()'lets reset the timer we used for the while loop:timer.mark()for each sprite in sprarrdata=sprite.getdata()data.movex=(rnd(3)-2)data.movey=(rnd(3)-2)sprite.setdata(data)movetimer.mark()end forwhile timer.totalseconds() < 60screen.clear(&h000000ff)if movetimer.totalmilliseconds() > 500 thenfor each sprite in sprarrdata=sprite.getdata()xr=(rnd(3)-2)yr=(rnd(3)-2)if xr <>0 then data.movex=xrif yr <>0 then data.movey=yrsprite.setdata(data)movetimer.mark()end forend if'move spritesfor each sprite in sprarrdata=sprite.getdata()x=data.xposy=data.yposx=x+data.movexy=y+data.moveyif x > bounds.x then x=0-sprite.getregion().getbitmap().getwidth()if y > bounds.y then y=0-sprite.getregion().getbitmap().getheight()if x < 0-sprite.getregion().getbitmap().getwidth() then x=bounds.xif y < 0-sprite.getregion().getbitmap().getheight() then y=bounds.ysprite.moveto(x,y)sprite.setdata({xpos:x,ypos:y,movex:data.movex,movey:data.movey})end forcompositor.drawall() 'draw all sprites even if they have not moved or changedscreen.swapbuffers() 'swap screen buffers to display completed drawingend whileend subJoel

Changing From roImageCanvas to roScreen questions

17 Replies

RokuJoel
Binge Watcher
14 years ago
You can use Adobe Photoshop or the gIMP which is free, or another graphic editor that allows you to manipulate images in .png format.

- Joel
kbenson
Visitor
14 years ago
It's worth noting (just in case you are using it) that rotation in roScreen is not equivalent to rotation in roImageCanvas. Last time I checked, roScreen could only rotate by 90 degree increments.

P.S. We would *happily* write a compatibility library so you could use roScreen like roImageCanvas if rotation was fixed, as we would be doing it anyway to fix KidPaint. Really, the only thing that's kept KidPaint from being fixed from the buggy implementation that exists using multiple (many!) canvases is that the rotation we need can't be achieved through roScreen. We would actually implement rotation ourselves (albeit slowly) if we could convert both directions between bytearray and roBitmap, but that's missing as well last time I checked. In fact that's what blocked us getting a very low-end (slow) VNC client working (the TCP server that speaks the protocol is written already...).
RokuJoel
Binge Watcher
14 years ago
Since 4.5 or so firmware, you can rotate to any angle.

- Joel
kbenson
Visitor
14 years ago
"RokuJoel" wrote:
Since 4.5 or so firmware, you can rotate to any angle.

Hmm, then I guess I have some work to do, don't I? 😉
TheEndless
Roku Guru
14 years ago
"kbenson" wrote:
"RokuJoel" wrote:
Since 4.5 or so firmware, you can rotate to any angle.

Hmm, then I guess I have some work to do, don't I? 😉

I was actually testing this out the other day.. don't get your hopes up too high... 😉
Also, still limited to 90 degree rotations on the Roku 1.
kbenson
Visitor
14 years ago
"TheEndless" wrote:
"kbenson" wrote:
"RokuJoel" wrote:
Since 4.5 or so firmware, you can rotate to any angle.

Hmm, then I guess I have some work to do, don't I? 😉

I was actually testing this out the other day.. don't get your hopes up too high... 😉
Also, still limited to 90 degree rotations on the Roku 1.

Actually, I just checked some old email, and I was notified about this. I think the lack of arbitrary rotation angles on the Roku 1 that caused me to not go forward with creating a roImageCanvas shim. So, first, sorry to Roku for shooting my mouth off about it not being supported, that's what I get for not paying attention.

Second, since I said I would work on implementing the an roImageCanvas to roScreen shim if they provided rotation, I'll at least try. 🙂
Sike1234
Visitor
10 years ago
Guys

I'm working on a Scene Graph project and I have to overlay a non-transparent image over video while it is playing.
I saw this example and believe it is a great place to start. Looking at the 2DVideoLayers example (note : great example )

I changed the object from roScreen to roSGScreen ... and ran into some issues.

orig = screen=createobject("roscreen",true)
new screen=createobject("roSGScreen",true)

I made some changes and did some debugging to find that I get stuck on line 119 screen.setalphaenable(true) 'enable transparency

roSGScreen does not have this method and I was wondering what the equivalent for setaplhaenable(true) might be using the roSGScreen object ?

Ran into some issues and wanted to ask someone if I'm going in the right direction.

Also trying to use roVideoPlayer instead of roVideoScreen.... and then use roImageCanvas to paint the image on top of the video.

Any suggestions / help

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Changing From roImageCanvas to roScreen questions

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