Android Code Snippet [B4XPages]Dynamically switching screen orientation while using B4XPages

bparent · Dec 2, 2021

The idea is to detect orientation dynamically and when it changes - restart the App so that B4XPages is initialized with the new orientation.
The App state can be saved and reloaded.

Update: It is tested with Android 11 but there may be problems under Android 12, I am investigating.
Update: It is now tested with Android 12 and works fine.
https://www.b4x.com/android/forum/t...-8-it-works-in-android-7-0.136393/post-863493

The Main Module

B4X:

#Region  Project Attributes
    #ApplicationLabel: TestOrient
    #VersionCode: 1
    #VersionName:
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified   'IMPORTANT
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
#End Region

'#BridgeLogger: True

Sub Process_Globals
    Public ActionBarHomeClicked As Boolean
    Public MyAppState As Map

    Private accelerometer As PhoneSensors    'include Phone library
    Private accValues() As Float
    Private LastOrientation As Int
    Private checkOrientation As Timer
 
    Private rp As RuntimePermissions        'include RuntimePermissions library
    Private myDir As String
    Dim ser As B4XSerializator                'include RandomAccessFile library
End Sub

Sub Globals
End Sub

Sub Activity_Create(FirstTime As Boolean)
    MyAppState.Initialize
    myDir = rp.GetSafeDirDefaultExternal("")
    If FirstTime = False Then MyAppState = ser.ConvertBytesToObject(File.ReadBytes(myDir, "MyAppState.dat"))

    Dim ph As Phone
    Dim orientation As String = "Landscape"
    If Activity.width < Activity.Height Then
        ph.SetScreenOrientation(7)
        LastOrientation = 7
        orientation = "portrait"
    Else
        ph.SetScreenOrientation(6)
        LastOrientation = 6
    End If
    Log("Activity started with orientation: " & orientation)
    accelerometer.Initialize(accelerometer.TYPE_ACCELEROMETER)
    checkOrientation.Initialize("chkOrient", 333)
    checkOrientation.Enabled = True

    Dim pm As B4XPagesManager
    pm.Initialize(Activity)
End Sub

Sub chkOrient_Tick
    accelerometer.StartListening("Accelerometer")
    Sleep(100)
    accelerometer.StopListening
End Sub

'The method for sensing orientation change is extracted from @emexes:
'https://www.b4x.com/android/forum/t...-with-portrait-orientation.106872/post-669094
Private Sub Accelerometer_SensorChanged (Values() As Float)
    checkOrientation.Enabled = False
    accValues = Values
    Dim X As Float = accValues(0)
    Dim Y As Float = accValues(1)
    Dim ThisOrientation As Int = LastOrientation
    If Abs(Y) > 7 Then ThisOrientation = 7
    If Abs(X) > 7 Then ThisOrientation = 6
    If ThisOrientation <> LastOrientation Then
        File.WriteBytes(myDir, "MyAppState.dat", ser.ConvertObjectToBytes(MyAppState))
        Activity.Finish
        StartActivity(Me)
        LastOrientation = ThisOrientation
    Else
        checkOrientation.Enabled = True
    End If
End Sub

'Template version: B4A-1.01
#Region Delegates

Sub Activity_ActionBarHomeClick
    ActionBarHomeClicked = True
    B4XPages.Delegate.Activity_ActionBarHomeClick
    ActionBarHomeClicked = False
End Sub

Sub Activity_KeyPress (KeyCode As Int) As Boolean
    Return B4XPages.Delegate.Activity_KeyPress(KeyCode)
End Sub

Sub Activity_Resume
    B4XPages.Delegate.Activity_Resume
End Sub

Sub Activity_Pause (UserClosed As Boolean)
    B4XPages.Delegate.Activity_Pause
End Sub

Sub Activity_PermissionResult (Permission As String, Result As Boolean)
    B4XPages.Delegate.Activity_PermissionResult(Permission, Result)
End Sub

Sub Create_Menu (Menu As Object)
    B4XPages.Delegate.Create_Menu(Menu)
End Sub

#if Java
public boolean _onCreateOptionsMenu(android.view.Menu menu) {
     processBA.raiseEvent(null, "create_menu", menu);
     return true;
 
}
#End If
#End Region

'Program code should go into B4XMainPage and other pages.

The B4XMainPage Module

B4X:

#Region Shared Files
#CustomBuildAction: folders ready, %WINDIR%\System32\Robocopy.exe,"..\..\Shared Files" "..\Files"
'Ctrl + click to sync files: ide://run?file=%WINDIR%\System32\Robocopy.exe&args=..\..\Shared+Files&args=..\Files&FilesSync=True
#End Region

'Ctrl + click to export as zip: ide://run?File=%B4X%\Zipper.jar&Args=Project.zip

Sub Class_Globals
    Private Root As B4XView
    Private xui As XUI
    Private Label1 As Label
End Sub

Public Sub Initialize
End Sub

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.LoadLayout("MainPage")
 
    If Main.MyAppState.size = 0 Then            'The first orientation
        Main.MyAppState.Put("OrientationCount", 1)
    Else
        Main.MyAppState.Put("OrientationCount", 1 + Main.MyAppState.Get("OrientationCount"))
    End If
    Label1.Text = IIf(Root.Width>Root.Height, "Now Landscape", "Now Portrait") & " Change # " & Main.MyAppState.Get("OrientationCount").As(Int)
End Sub

I am getting error on this line
Label1.Text = IIf(Root.Width>Root.Height, "Now Landscape", "Now Portrait") & " Change # " & Main.MyAppState.Get("OrientationCount").As(Int)
that Int is not a valid indentifier.

William Lancee · Dec 2, 2021

If you have an earlier version of B4A, then break the line up.

B4X:

Dim n As int = Main.MyAppState.Get("OrientationCount")

If Root.Width>Root.Height then
    Label1.Text = "Now Landscape"  & " Change # " & n
Else
   Label1.Text = "Now Portrait"  & " Change # " & n
End If

bparent · Dec 3, 2021

William Lancee said:
If you have an earlier version of B4A, then break the line up.

B4X:

Dim n As int = Main.MyAppState.Get("OrientationCount") If Root.Width>Root.Height then Label1.Text = "Now Landscape" & " Change # " & n Else Label1.Text = "Now Portrait" & " Change # " & n End If

Thanks, I upgraded from 10.xx to 11.00 and now don't get the error message anymore. I am running Android 11 and get portrait changes, but never any landscape number or change.

William Lancee · Dec 3, 2021

Are you using a real device? Yes you are since you can't rotate your simulator.

There are two parameters that may be sensitive to the speed and/or sensors of the device.
In above code one is 333, the interval between checking orientation.
The other is 100 which is the period in which to detect rotations from the sensors. It may be too small.

bparent · Dec 4, 2021

William Lancee said:
Are you using a real device? Yes you are since you can't rotate your simulator.

There are two parameters that may be sensitive to the speed and/or sensors of the device.
In above code one is 333, the interval between checking orientation.
The other is 100 which is the period in which to detect rotations from the sensors. It may be too small.

Latest results:
First of all I am running Android version 12 with One UI version 4.0 . I changed the 100 parameter to 300 and it now I see the portrait and landscape screens with their respective change #.

Thanks.

William Lancee · Dec 4, 2021

Thank you for testing, I will change the parameter.

Android Code Snippet [B4XPages]Dynamically switching screen orientation while using B4XPages

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