Android Question [B4X] B4XPages - destroy page to trigger B4XPage_Created again

Alexander Stolte · Jun 15, 2020

Hey,

i have a display problem, i take a image from the camera, then i open a new page to load the image to edit it.
If I would now load the image in the "appear" sub, you will see the old image, until the new one is loaded and all the settings on the page are still there because the page was not destroyed. Another problem is when I load the image in the "appear" sub, if the user briefly leaves the app and comes back, then the image would be loaded again.

So how i can destroy the page?

Thanks

Erel · Jun 15, 2020

Why aren't you setting the image from the camera page directly? Set it before you show the next page.

Pages are not destroyed. If you want to reset the UI then create a Reset sub in the page and configure the UI as needed. You can remove all views (Root.RemoveAllView) and load them again if you like.

Alexander Stolte · Jun 15, 2020

Erel said:
Why aren't you setting the image from the camera page directly? Set it before you show the next page.

Because the page was not loaded before, I know with "AddPageAndCreate" I can load the page directly, but if the user doesn't take a new image, then I don't need the page, so this would be an unnecessary operation or page that is loaded and not needed.
Maybe a "CreatePage" function would help, so I could preload the next page if it has not yet been created, load the image before displaying the page.

Erel said:
Pages are not destroyed. If you want to reset the UI then create a Reset sub in the page and configure the UI as needed.

But then you would also have to make sure that the custom views can be reset. So I would have to add the "Reset" function to my "AS Draw" to reset the painted and the image.

Erel · Jun 16, 2020

Alexander Stolte said:
Because the page was not loaded before, I know with "AddPageAndCreate" I can load the page directly, but if the user doesn't take a new image, then I don't need the page

This is a preoptimization thinking. Creating a panel with a few views will take less than a few milliseconds. Nothing to be bothered about.

Alexander Stolte said:
But then you would also have to make sure that the custom views can be reset. So I would have to add the "Reset" function to my "AS Draw" to reset the painted and the image.

As I said, you have two options:
1. Reset the layout.
2. Remove the layout and load it again.

Both are simple and don't require dealing with the class instance state being lost.

Alexander Stolte · Jun 16, 2020

Erel said:
2. Remove the layout and load it again.

I have decided to go for the second option.

But it needs some config.

B4X:

Sub Class_Globals
Private justinbackground As Boolean = False
Private pageclosed As Boolean = True
End Sub

Private Sub B4XPage_Appear
pageclosed = True
    If justinbackground = False Then
    'LoadLayout
    End If
End Sub

Private Sub B4XPage_Background
    pageclosed = False
    justinbackground = True
End Sub

Private Sub B4XPage_Disappear
    Sleep(0)
    If pageclosed = True Then
        justinbackground = False
        Root.RemoveAllViews
    End If
End Sub

The code prevents the layout from being reset if the user moves the app to the background and then continues the process.
If the user goes back, the layout is reset.

incendio · Jan 20, 2021

In my case, I have these codes to handle this situation

B4X:

Sub B4XPage_Appear
    Root.RemoveAllViews
    Root.LoadLayout("mylay")
    'others codes from B4XPage_Created move to this sub
End Sub

Android Question [B4X] B4XPages - destroy page to trigger B4XPage_Created again

Alexander Stolte

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Alexander Stolte

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Alexander Stolte

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incendio

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