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roquoonewbie's avatar
roquoonewbie
Visitor
14 years ago

EnableBackButton does not work unless AddButton is used

I think there is a bug with the roMessageDialog object. Specifically, I cannot get the back button event unless I also add a button to the dialog.

I do not want to have any button on the dialog, but I do want the user to be able to press back to quit the dialog. However, in the below code, the only way I can get the event is if I include a dummy button. Can anyone confirm they see the same? Can Roku confirm this is a bug?


Function testBackButton() As Void

port = CreateObject("roMessagePort")
dialog = CreateObject("roMessageDialog")
dialog.SetMessagePort(port)
dialog.SetText("Testing Back Button")
dialog.EnableBackButton(true)
dialog.AddButton(1, "Go Back") 'This line must be present otherwise back button event never occurs
dialog.Show()

while true
dlgMsg = wait(0, port)
if type(dlgMsg) = "roMessageDialogEvent"
Dbg("EVENT RECEIVED") 'Never gets executed unless AddButton is included above
if dlgMsg.isScreenClosed() or dlgMsg.isButtonPressed()
exit while
end if
end if
end while

End Function
Roku Developer Program

19 Replies

  • TheEndless's avatar
    TheEndless
    Channel Surfer
    14 years ago
    If you don't want buttons, then you might want the roOneLineDialog, but I don't think it supports the back button, so moot point.
  • roquoonewbie's avatar
    roquoonewbie
    Visitor
    14 years ago
    Yes, kind of a moot point. I want a title and text in the dialog, but no on screen buttons, so that is why roMessageDialog is a good fit. I didn't include the text in my example because it does not impact the resulting behavior either way.

    I don't understand why the remote control back button event has any dependency at all on the presence of on-screen buttons.

    Do you see the same?

    I have a Roku 2.
  • roquoonewbie's avatar
    roquoonewbie
    Visitor
    14 years ago
    I should probably describe the use case here a bit more. When the user selects a specific poster, I need to get a lot of metadata from the web before I can proceed to building the next screen. Sometimes, that can take a long time (depending on network and server conditions). So I present a "Please wait" dialog while I am getting the info.

    Right now, the user is "stuck" on this dialog screen with no way to back out. I want to give them a way to cancel the request and go back to where they were.

    Is there a Roku "best practice" or example around this, given that the back button does not seem to work?
  • RokuMarkn's avatar
    RokuMarkn
    Visitor
    14 years ago
    Why not just put a "cancel" button on the dialog? That seems more discoverable by the user than Back. Especially since some users don't have a Back button on their remote.

    --Mark
  • roquoonewbie's avatar
    roquoonewbie
    Visitor
    14 years ago
    I think that is the route I have to go. Is there any sample code that demonstrates how to kick off some web requests, while listening for an event (whether that is a back button or on screen button event), and canceling the web request process to go back a screen if one of those events happen?

    I am having trouble killing the web request process when I get the event.
  • TheEndless's avatar
    TheEndless
    Channel Surfer
    14 years ago
    "roquoonewbie" wrote:
    I think that is the route I have to go. Is there any sample code that demonstrates how to kick off some web requests, while listening for an event (whether that is a back button or on screen button event), and canceling the web request process to go back a screen if one of those events happen?

    I am having trouble killing the web request process when I get the event.

    I think you want to look at roUrlTransfer.AsyncGetToString and roUrlTransfer.AsyncCancel. Listen on the same port as your message dialog, and you should be good to go. Take a look at the http_get_to_string_with_timeout function in the urlUtils.brs file in the videoplayer SDK app for an example.
  • roquoonewbie's avatar
    roquoonewbie
    Visitor
    14 years ago
    Here is an example of what I mean. I want to kick off the function called "doStuffThatTakesAWhile" while I show a "Please Wait" dialog. If the user cancels the request before the "stuff that takes a while" completes, I want it to stop executing that code. But when I set it up as shown below, the output I print shows that doStuffThatTakesAWhile() completes all of its logic before the event handler even gets the message that the customer clicked cancel. The odd thing is that the dialog does in fact close on the screen when I press cancel...long before the line is logged that "User canceled out of dialog".


    Output:

    ------ Running ------
    Got to beginning of doStuffThatTakesAWhile Function
    This line should not get executed if user presses back in less than 10 seconds!
    User canceled out of dialog



    Function testBackButton() As Void

        port = CreateObject("roMessagePort")
        dialog = CreateObject("roMessageDialog")
        dialog.SetMessagePort(port)
        dialog.SetText("Please Wait")
        dialog.EnableBackButton(true)
        dialog.AddButton(1, "Go Back")
        dialog.Show()

    	while true
    		dlgMsg = wait(10, port)
    		if type(dlgMsg) = "roMessageDialogEvent" then
    			if dlgMsg.isScreenClosed() or dlgMsg.isButtonPressed()
    				Dbg("User canceled out of dialog")
    				exit while
    			end if
    		else if dlgMsg = invalid then
    			doStuffThatTakesAWhile()	
    		endif
        end while

    End Function

    Function doStuffThatTakesAWhile() as Void
    	Print("Got to beginning of doStuffThatTakesAWhile Function")
    	sleep(10000)
    	Print("This line should not get executed if user presses back or cancel in less than 10 seconds!")
    End Function
  • RokuJoel's avatar
    RokuJoel
    Binge Watcher
    14 years ago
    Don't make your "DoStuff" function separate from your dialog function. instead, integrate the "stuff" with the loop that waits for input.

    - Joel
  • roquoonewbie's avatar
    roquoonewbie
    Visitor
    14 years ago
    Why is that necessary? And how would it help? Besides being completely impractical (because the "stuff that takes a while" in my actual code calls all kinds of re-usable HTTP, URL, and XML functions), I don't see how that would change the result at all either way.

    Confirmed...same result if I move the 3 lines of sample code into the event loop.


    Output:

    ------ Running ------
    Got to beginning of doStuffThatTakesAWhile Function
    This line should not get executed if user presses back in less than 10 seconds!
    User canceled out of dialog



    	while true
    		dlgMsg = wait(10, port)
    		if type(dlgMsg) = "roMessageDialogEvent" then
    			if dlgMsg.isScreenClosed() or dlgMsg.isButtonPressed()
    				Dbg("User canceled out of dialog")
    				exit while
    			end if
    		else if dlgMsg = invalid then
    			Print("Got to beginning of doStuffThatTakesAWhile Function")
    			sleep(10000)
    			Print("This line should not get executed if user presses back in less than 10 seconds!")	
    		endif
        end while
  • renojim's avatar
    renojim
    Community Streaming Expert
    14 years ago
    You're basically giving the user 10ms to press the back button. You need to use an roTimespan object and check every 10ms if 10 seconds have passed. Each time through the loop you have to do a part/i] of the stuff that takes a while. If your stuff can't be broken up, then you don't have much choice but to do it all and put up a "please wait" message. I'll leave the details to the interested reader.

    -JT