Android Question ScrollPosition Not Work

[Artur Martins]

scrollPosition does not work in the following code:

Sub IME_HeightChanged (NewHeight As Int, OldHeight As Int)
    Dim rol_scrol As Int
 
    If NewHeight = 100%y Then
        scroll.Panel.Height = 81%y + 100%y - NewHeight
    Else
        scroll.Panel.Height = 71%y + 100%y - NewHeight
    End If
 
    rol_scrol = posicao_tela - NewHeight
 
    scroll.ScrollPosition = rol_scrol

End Sub

Why?

 

[Cableguy]

Olá Artur

Já tentaste fazer Log(rol_Scrol) para saber qual o valor que lhe esta a ser atribuido?
Onde vais buscar o valor 'posicao_tela'?
Apenas com essa sub nao podemos saber exactamente o que se passa pois estas a usar variaveis que nao sabemos a sua origem.

Hi Artur

Have you tried logging rol_scrol to see its value?
Where do you get 'posicao_tela' value?
With only this sub it's hard to tell where the error lies as you use vars that we don't know their origin.

 

[Artur Martins]

hello cableguy

in a test with logs

rol_scrol the value is 131

after that the scroll.scrollposition value continued to 0

 

[klaus]

What exactly doesn't work ?
I don't understand why you change the height of internal panel of the scrollview ?

 

[Artur Martins]

hello Klaus

In this case my scroll bar remains in the same position after the command scrollPosition.

The Intent of this code is to create a scroll bar at the time the keyboard is turned on, so I can roll this bar and view other views.

 

[klaus]

Try to add a DoEvents after scroll.ScrollPosition = rol_scrol.

 

[Erel]

It is better to use ScrollToNow and avoid the DoEvents call.

 

[klaus]

In the clsWheel class I even needed this to ensure the scrolling:

scvWheel(i).ScrollToNow(ScrollPos(i))
DoEvents
scvWheel(i).ScrollToNow(ScrollPos(i))
DoEvents

 

[Artur Martins]

DoEvents and ScrollToNow not work

 

[klaus]

I'm afraid that we are turning in circle.
You should post a small project showing the problem so we could see what you have done and how and test it.

 

[Artur Martins]

ok I will summarize my project and probably tomorrow will be posting here to continue the discussion

Thanks

 

[Artur Martins]

I can not upload my project in .zip, then follow the code source of the project:

#Region  Project Attributes 
    #ApplicationLabel: B4A Example
    #VersionCode: 1
    #VersionName: 
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified
    #CanInstallToExternalStorage: False
#End Region

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

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.

End Sub

Sub Globals
    Dim painel As Panel
    Dim et_descricao As EditText
    Dim tv_fabric As Label
    Dim IME As IME
    Dim scroll As ScrollView
    Dim posicao_tela As Int
   
End Sub

Sub Activity_Create(FirstTime As Boolean)

    Activity.Color = Colors.RGB(255,112,67)
   
    IME.Initialize("IME")
    IME.AddHeightChangedEvent
   
    scroll.Initialize2(81%y,"scroll")
   
    painel.Initialize("painel")
    painel.Color = Colors.White
   
   
    et_descricao.Initialize("et_descricao")
    et_descricao.Hint = "Descrição"
    et_descricao.ForceDoneButton = True
    et_descricao.SingleLine = True
   
   
    tv_fabric.Initialize("tv_fabric")
    tv_fabric.Text = "Cadastro de fornecedor"
    tv_fabric.Gravity = Gravity.CENTER
    tv_fabric.TextSize = 20
    tv_fabric.Typeface = Typeface.CreateNew(Typeface.MONOSPACE,Typeface.STYLE_BOLD)
   
    painel.AddView(et_descricao,1%x,70%y,98%x,75)
   
    Activity.AddView(tv_fabric,0,0,100%x,9%y)
    Activity.AddView(scroll,0,9%y,100%x,81%y)
    scroll.Panel.AddView(painel,0,0,100%x,81%y)
       
End Sub

Sub IME_HeightChanged (NewHeight As Int, OldHeight As Int)
    Dim rol_scrol As Int
   
    If NewHeight = 100%y Then
        scroll.Panel.Height = 81%y + 100%y - NewHeight
    Else
        scroll.Panel.Height = 71%y + 100%y - NewHeight
    End If
           
    rol_scrol = posicao_tela - (NewHeight - 9%y)
   
    scroll.ScrollToNow(rol_scrol)

End Sub

Sub et_descricao_FocusChanged (HasFocus As Boolean)
    If HasFocus Then
        posicao_tela = et_descricao.Top + et_descricao.Height
    End If
End Sub

Sub Activity_Resume
   
End Sub


Sub Activity_Pause (UserClosed As Boolean)
   
End Sub

sorry for the delay, now I lack time.

 

[klaus]

Why can't you post the project ?
To export the project, as a zip file, use the IDE menu File / Export As Zip and then upload the zip file to the post.

For the height of et_descricao you should use 75dip instead of 75.

There seems to be a problem with scroll position change after a ScrollView.Panel.Heigt change.
Erel, you should have a look at the attached project, it's a modifyed version of the code in post#12.

EDIT: 2012.03.08 Added a modified version after Erels answer.

 

[Erel]

I've changed CallSub2 to CallSubDelayed2 and it seems to solve this issue. The ScrollView new height is not immediately gets updated. It needs to handle the message queue first.

 

[klaus]

Thank you Erel.
The frustrating thing for me is that I was thinking CallSubDelayed2 but put CallSub2 in the code.

 

[Artur Martins]

worked perfectly, Thanks to all