Android Question drawing an arc

[FrankDev]

Hello,

I would like to draw an arc in the header of an activity.
What is the best way to do this?
A huge circle whose centre is negatively above the top of the activity ?

Regards Frank

 

[William Lancee]

Yes. Use B4XCanvas and B4XPath. Of course as a custom header you use full screen, no title, and add your own decorations.

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Dim headerPanel As B4XView = xui.CreatePanel("")
    headerPanel.Color = xui.Color_Red
    Root.AddView(headerPanel, 0, 0, Root.width, .075 * Root.height)
    Dim cv As B4XCanvas
    cv.initialize(headerPanel)
   
    Dim radius As Float = 2 * Root.Width
    Dim path As B4XPath
    path.InitializeArc(headerPanel.width/2, -radius + headerPanel.height - 5dip, radius, 70, 40)
    cv.DrawPath(path, xui.Color_Blue, True, 0)
       
End Sub

 

[TILogistic]

just a small adjustment, as requested.

    Dim headerPanel As B4XView = xui.CreatePanel("")
    headerPanel.Color = xui.Color_Transparent
    Root.AddView(headerPanel, 0, 0, Root.width, .20 * Root.height)

and

headerPanel.SendToBack

 

[FrankDev]

hello @William Lancee ,

yes... that's exactly how I imagined it

Best regards
Frank

 

[William Lancee]

And a small adjustment by me.

Don't forget to invalidate the cv on Android when the drawing is done.
I almost always do, and have to track it down.

 

[FrankDev]

hi @William Lancee

I need this to draw a header on several activities.

Do I do this for each page ?

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Dim headerPanel As B4XView = xui.CreatePanel("")
    headerPanel.Color = xui.Color_Red
    Root.AddView(headerPanel, 0, 0, Root.width, .075 * Root.height)
    Dim cv As B4XCanvas
    cv.initialize(headerPanel)
  
    Dim radius As Float = 2 * Root.Width
    Dim path As B4XPath
    path.InitializeArc(headerPanel.width/2, -radius + headerPanel.height - 5dip, radius, 70, 40)
    cv.DrawPath(path, xui.Color_Blue, True, 0)
    
     invalidate.cv ''?????   <----------------------------------------------------------
      
End Sub

 

[William Lancee]

Yes, each activity and on each page that you want it, BUT only once for each.

Are you using B4XPages? It will save you a lot of headaches.
There is only one activity (and you won't need a header there), a simple life cycle, and lots of pages (each can be thought of as screen/form).
The code above should be put in the B4XPage_Created sub of each page.

If you are not using B4XPages, then you need to modify the code by using "Activity" instead of "Root" and put the code in each Activity.
Put it in Activity_Create, but not just the first time. It needs to be done each time the Activity is created (which happens when Resumed after a Pause)
That's why B4XPages is better.

P.S. You will need the XUI library.

And it is:

cv.Invalidate

 

[FrankDev]

Hello @oparra,

Thank you very much.
Exactly... I needed it transparent.

best regards
Frank