iOS Question A canvas in B4XPages

klaus

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• Mar 29, 2021

• #2

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:

B4X:

Private xpnlGraph As B4XView
Private xcvsGraph As B4XCanvas

And in Sub B4XPage_Created:

B4X:

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

 

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Aldo's

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• Mar 29, 2021

• #3

I try and then I tell you

 

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Aldo's

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• Mar 29, 2021

• #4

This is my code:

B4X:

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.

 

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Semen Matusovskiy

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• Mar 29, 2021

• #5

Add xcvsGraph.Invalidate after xcvsGraph.DrawText

 

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Aldo's

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• Mar 29, 2021

• #6

it works. Thank you very much

 

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klaus

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• Mar 29, 2021

• #7

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

 

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Aldo's

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• Mar 29, 2021

• #8

klaus said:

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

Click to expand...

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

 

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klaus

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• Mar 29, 2021

• #9

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.

 

Last edited: Mar 29, 2021

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Aldo's

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• Mar 29, 2021

• #10

klaus said:

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

Click to expand...

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

 

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klaus

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• Mar 29, 2021

• #11

You are right, it is called cvsGraph.Refresh.

 

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Aldo's

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• Mar 29, 2021

• #12

Thanks for all your answers.

 

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klaus

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• Mar 29, 2021

• #13

Aldo's said:

I think it is also necessary in B4I ...

Click to expand...

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.

 

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