iOS Question A canvas in B4XPages

[Aldo's]

Hi, I have a B4 XPages project. I didn't understand how to create a B4XCanvas on a sub page. In Designer it doesn't let me add it. Can you help me?

 

[klaus]

You need to add a Panel in the Designer and declare it as a B4XView. Then in the code link the B4XCanvas to the Panel.
Something like this:

Private xpnlGraph As B4XView
Private xcvsGraph As B4XCanvas

And in Sub B4XPage_Created:

Private Sub B4XPage_Created (Root1 As B4XView)
    xcvsGraph.Initialize(xpnlGraph)

 

[Aldo's]

I try and then I tell you

 

[Aldo's]

This is my code:

Sub Class_Globals
    Private Root As B4XView
    Private xui As XUI
    Private pnlGraph As B4XView
    Private xcvsGraph As B4XCanvas
End Sub

'Initializes the object. You can add parameters to this method if needed.
Public Sub Initialize
    
End Sub

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.LoadLayout("CantoLO")
    B4XPages.SetTitle(Me, Main.sCanto)
    xcvsGraph.Initialize(pnlGraph)
    xcvsGraph.DrawText("prova di scrittura con DrawText", 20, 50, Font.DEFAULT, xui.Color_Blue, "LEFT")
End Sub

opens the new page but does not execute the DrawText.

 

[Semen Matusovskiy]

Add xcvsGraph.Invalidate after xcvsGraph.DrawText

 

[Aldo's]

it works. Thank you very much

 

[klaus]

Did you have a look at the B4X Booklets ?
And more specifically the B4X Graphics booklet.

 

[Aldo's]

Did you have a look at the B4X Booklets ?
And more specifically the B4X Graphics booklet.

Yes, but the .Invalidate it isn't shown in the individual examples.
I read superficially.

 

[klaus]

I added a small chapter in the B4X Graphics booklet to highlight it.
It is only needed in B4A or XUI.
Edit: In B4i it is called Refresh instead of Invalidate.

 

[Aldo's]

I added a small chapter in the B4X Graphics booklet to highlight it.
It is only needed in B4A or XUI.

I think it is also necessary in B4I ...
it didn't work before.

 

[klaus]

You are right, it is called cvsGraph.Refresh.

 

[Aldo's]

Thanks for all your answers.

 

[klaus]

I think it is also necessary in B4I ...

Just to clarify.
Perhaps I misread your post.
In pure B4i, with a B4i Canvas, it is needed with cvsGraph.Refresh.
In B4i, with a B4XCanvas, it is needed with cvsGraph.Invalidate.