Android Question VisibleRangeChanged problems with imagedownloader

Carlos marin · Jun 29, 2018

hello experts I'm looking in the forums to clear a doubt and I can not find an answer.
with this code I download images from the server but I do not know how to fit it to my code.

Code: Copy

links.Put(img2, "http://www.miweb.com/solodomi/aliados/"&id_emp&"/productos/"&cd.id&".png")
CallSubDelayed2(ImageDownloader, "Download", links)

i use VisibleRangeChanged to load my customlistview

Code: Copy

Private Sub CreateItem(Width As Int, Title As String, id  As String, nombre  As String, descripcion  As String, precio  As String, items  As String )
    Dim p As B4XView = xui.CreatePanel("")
    Dim height As Int = 155dip
    If GetDeviceLayoutValues.ApproximateScreenSize < 4.5 Then height = 170dip
    Dim cd As CardData
    cd.Initialize
    cd.Title = Title
    cd.id = id
    cd.nombre = nombre
    cd.descripcion = descripcion
    cd.precio = precio
    cd.items = items
    p.SetLayoutAnimated(0, 0, 0, Width, height)
    CLV.Add(p, cd)
End Sub

Code: Copy

Sub CLV_VisibleRangeChanged (FirstIndex As Int, LastIndex As Int)
    Dim ExtraSize As Int = 20
   
    For i = 0 To CLV.Size - 1
        Dim p As B4XView = CLV.GetPanel(i)
        If i > FirstIndex - ExtraSize And i < LastIndex + ExtraSize Then
            'visible+
            If p.NumberOfViews = 0 Then
                Dim cd As CardData = CLV.GetValue(i)
                p.LoadLayout("CellItem2")
                lblnombre.Text = cd.nombre
                lbldescripcion.Text = cd.descripcion
                lblprecio.Text = cd.precio
                If miclase.pantalladip = "Gama-baja" Then
                    lblnombre.TextSize = 10
                    lbldescripcion.TextSize = 9
                    lblprecio.TextSize = 13
                    lblpeso.TextSize = 12
                End If
               ImgCpanel.SetBackgroundImage(LoadBitmapSample(File.DirAssets,"PnlProdMesa.png",25%x,25%y))
                btnmas.Tag = cd.id & "-" & cd.nombre & "-" & cd.descripcion & "-" & cd.precio & "-" & cd.items
                img2.Tag = cd.id & "-" & cd.nombre  & "-" & cd.descripcion & "-" & cd.precio & "-" & cd.items
                img2.Visible = True
                'CallSubDelayed2(ImageDownloader, "Download", links)
                fuente
            End If
        Else
            'Not visible
            If p.NumberOfViews > 0 Then
                p.RemoveAllViews
            End If
        End If
    Next
End Sub

where I insert the code ImageDownloader?, what is the correct and optimized way? any help

Peter Simpson · Jun 29, 2018

Hello @Carlos marin,
That's all wrong for integrating lazy loading.

You do not need the 'CreateItem Sub' sub anymore, I suggest that you read Erel's tutorial again. You only need to integrate a part of the original 'CreateItem Sub' into 'FillList2 Sub'.

Enjoy...

Carlos marin · Jun 29, 2018

Hello Peter, I do not understand what you are saying, I did it following this tutorial, the only thing I need to know is how to upload images from the Internet. I use the imagedownloader. and I tried to adapt it in filllist2 without success

(my CreateItem = FillList2 if you mean that)

Code: Copy

 links.Put (img2, "[URL]http://www.miweb.com/solodomi/aliados/[/URL]"&id_emp&"/productos/"&cd.id&".png")
CallSubDelayed2 (ImageDownloader, "Descargar", enlaces)

Carlos marin · Jun 29, 2018

I tried this but I do not get the result I need

Code: Copy

Type CardData ( bm As ImageView)
Sub FillList2
    '...code
    cd.bm.Initialize("")
    cd.bm.Width = 130dip
    cd.bm.Height = 100dip
    cd.bm.Bitmap = LoadBitmapSample(File.DirAssets, "icofood2.jpg",15%x,15%y)
    links.Put(cd.bm, "http://www.miweb.com/solodomi/aliados/"&id_emp&"/productos/"&cd.id&".png")
End Sub

now in the VisibleRangeChanged I call the downloader

Code: Copy

Sub CLV_VisibleRangeChanged (FirstIndex As Int, LastIndex As Int)
    Dim ExtraSize As Int = 10
 
    For i = 0 To CLV.Size - 1
        Dim p As B4XView = CLV.GetPanel(i)
        If i > FirstIndex - ExtraSize And i < LastIndex + ExtraSize Then
            'visible+
            If p.NumberOfViews = 0 Then
                Dim cd As CardData = CLV.GetValue(i)
                '**************** this code is similar to the code in CreateItem from the

'code......
     
                CallSubDelayed2(ImageDownloader, "Download", links)
      
'code.......
            End If
        Else
            'Not visible
            If p.NumberOfViews > 0 Then
                p.RemoveAllViews
            End If
        End If
    Next
End Sub

and this are the results... (see pictures)
only uploads some images, when I scroll, is this the correct way?

Erel · Jul 1, 2018

I recommend you to start with a simpler approach. Create all items in Activity_Create.

Use VisibleRangeChanged to load the bitmaps. You can also remove invisible bitmaps. Make sure to call Job.GetBitmapResize to avoid loading large images. You might need to modify ImageDownloader for this.

Carlos marin · Jul 1, 2018

Erel said:
I recommend you to start with a simpler approach. Create all items in Activity_Create.

Use VisibleRangeChanged to load the bitmaps. You can also remove invisible bitmaps. Make sure to call Job.GetBitmapResize to avoid loading large images. You might need to modify ImageDownloader for this.

thanks Erel for answering. some example of how to load the bitmap?, the way I do it is not correct, but I do not see in any post how to do it. I have no idea how to do it

(all the Items I bring from a query from mysql server)

and now i try this!

Code: Copy

Type CardData ( bm As ImageView)
Sub FillList2
    '...code
    cd.bm.Initialize("")
    cd.bm.Bitmap = LoadBitmapSample(File.DirAssets, "icofood2.jpg",15%x,15%y)
    links.Put(cd.bm, "http://www.miweb.com/solodomi/aliados/"&id_emp&"/productos/"&cd.id&".png")
    CallSubDelayed2(ImageDownloader, "Download", links)
    p.SetLayoutAnimated(0, 0, 0, Width, height)

End Sub

in the VisibleRangeChanged

Code: Copy

Sub CLV_VisibleRangeChanged (FirstIndex As Int, LastIndex As Int)
    Dim ExtraSize As Int = 10
 
    For i = 0 To CLV.Size - 1
        Dim p As B4XView = CLV.GetPanel(i)
        If i > FirstIndex - ExtraSize And i < LastIndex + ExtraSize Then
            'visible+
            If p.NumberOfViews = 0 Then
                Dim cd As CardData = CLV.GetValue(i)
                '**************** this code is similar to the code in CreateItem from the

'code......
   
                img2.Bitmap = cd.bm.Bitmap
     
'code.......
            End If
        Else
            'Not visible
            If p.NumberOfViews > 0 Then
                p.RemoveAllViews
            End If
        End If
    Next
End Sub

the view is very stable but the images are only shown when I scroll down.
what is missing me??

Erel · Jul 2, 2018

This is how I would have done it:
1. Remove ImageDownloader. You don't need it.
2.

Code: Copy

Sub CLV_VisibleRangeChanged (FirstIndex As Int, LastIndex As Int)
    Dim ExtraSize As Int = 10
 
    For i = 0 To CLV.Size - 1
        Dim p As B4XView = CLV.GetPanel(i)
        If i > FirstIndex - ExtraSize And i < LastIndex + ExtraSize Then
            'visible+
            If p.NumberOfViews = 0 Then
                Dim cd As CardData = CLV.GetValue(i)
                '**************** this code is similar to the code in CreateItem from the

'code......
                Dim j As HttpJob
                Dim iv As ImageView = img2 'must be a local variable
                j.Initialize("", Me)
                j.Download(...)
                Wait For (j) JobDone(j As HttpJob) 
                if j.Success Then
 iv.Bitmap = j.GetBitmapResize(...)
 End If
 j.Release
                
     
'code.......
            End If
        Else
          'start simple. Don't remove anything
        End If
    Next
End Sub

Carlos marin · Jul 3, 2018

Erel said:

This is how I would have done it:
1. Remove ImageDownloader. You don't need it.
2.

Code: Copy

Sub CLV_VisibleRangeChanged (FirstIndex As Int, LastIndex As Int)
    Dim ExtraSize As Int = 10
 
    For i = 0 To CLV.Size - 1
        Dim p As B4XView = CLV.GetPanel(i)
        If i > FirstIndex - ExtraSize And i < LastIndex + ExtraSize Then
            'visible+
            If p.NumberOfViews = 0 Then
                Dim cd As CardData = CLV.GetValue(i)
                '**************** this code is similar to the code in CreateItem from the

'code......
                Dim j As HttpJob
                Dim iv As ImageView = img2 'must be a local variable
                j.Initialize("", Me)
                j.Download(...)
                Wait For (j) JobDone(j As HttpJob)
                if j.Success Then
 iv.Bitmap = j.GetBitmapResize(...)
 End If
 j.Release
               
    
'code.......
            End If
        Else
          'start simple. Don't remove anything
        End If
    Next
End Sub

It was just what I needed, Erel thank you very much! you're the best

Carlos marin · Jul 4, 2018

Hi Experts. working with VisibleRangeChanged and the code that Erel gave me, two things happen to me (when the user leaves the view quickly)
1. HttpJob takes a while to complete if the user leaves the activity, when HttpJob completes this it returns me to the original activity
2. I get an error

Code: Copy

java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0

my solution but sometimes the application stops with this error(see image). Any suggestions?

Code: Copy

StopService(HttpUtils2Service)

Erel · Jul 4, 2018

Please post error messages as text instead of screenshot.

Carlos marin said:
my solution but sometimes the application stops with this error(see image). Any suggestions?

This is a bad solution.

You should instead make the request from the starter service.

Carlos marin · Jul 4, 2018

Hi Erel this the error code:

Code: Copy

line 633: topService(HttpUtils2Service)

Error ocurred on line:633(productos)
java.lang.ClassCastException: anywheresoftware.b4a.samples.httputils2.httpjob cannot be cast to android.content.Intent

the user always leaves the view quickly this calls the event Activity_KeyPress how to control from here?

Erel · Jul 5, 2018

At this point it is better if you start a new thread and post the full error message and the relevant code.

Carlos marin · Jul 5, 2018

sure Erel I'm going to do it. Thanks

Android Question VisibleRangeChanged problems with imagedownloader

Carlos marin

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Peter Simpson

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Carlos marin

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Erel

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Erel

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Carlos marin

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