B4J Question Canvas to Image is not showing the Lines

[Swissmade]

Hi all,

I have a Canvas where I draw some lines on it.
When I save the Snapshot to a file I get nicely the Lines.
Code Snipper.

  img = cvs.Snapshot
  Dim Out As OutputStream
  Out = File.OpenOutput("c:\","Hello" & x1 & ".png",False)
  img.WriteToStream(Out)
  Out.Close
'Here I get the Drawing Lines from the cvs.Snapshot in a file
  gxIMG.SetImage(img)
'When I do this directly I don't See any line.

I don't need the file I like to have the Lines directly in the Image.
Saving the Image and Load again is no option because of performance.
Maybe some Refresh issues??
Hope anybody can help.

 

[Daestrum]

Does the image that you saved have the correct dimensions, I seem to recall a problem with images ending up at 1 x 1 pixel, but can't remember if it was related to canvas snapshots.

 

[Erel]

I've tried this code and it works:

Sub Process_Globals
   Private fx As JFX
   Private MainForm As Form
   Private cvs As Canvas
   Private iv As ImageView
End Sub

Sub AppStart (Form1 As Form, Args() As String)
   MainForm = Form1
   MainForm.Show
   cvs.Initialize("csv")
   MainForm.RootPane.AddNode(cvs, 0, 0, 100, 100)
   cvs.DrawCircle(50, 50, 20, fx.Colors.Red, True, 0)
   iv.Initialize("iv")
   MainForm.RootPane.AddNode(iv, 0, 100, 100, 100)
   iv.SetImage(cvs.Snapshot)
End Sub

You will see two red circles.

 

[Swissmade]

Does the image that you saved have the correct dimensions, I seem to recall a problem with images ending up at 1 x 1 pixel, but can't remember if it was related to canvas snapshots.

Yes the Image has the same dimension.

 

[Swissmade]

Hi Erel,
After your code has the same issue, I go to debug this and I found the problem.
The Event what is giving me the coordinates for the line is fired two times.
First with the coordinates where I see the lines and second without so the line is go away.
Happy to see that this is the problem and I can fix this.

To Explain what I'm doing.
I have build a library in Java to read License Plates. The Library build around a ANPR SDK I use already for about 10 Years.
The old Application I try to replace is written in VB6.
Working very fast and precisely.

After a plate is found, there will be all the coordinates to draw the line around the Plate.
Erel I think this is the first Application for ANPR in B4J



Many thanks for all your help in this.

 

[Swissmade]

It is not a error or bug the Library is doing what I ask.
I can read more then one plate on a Image so when the second read has not a second plate , I get the Image and zero coordinates back.

In the meantime its solved. just one boolean and its working fast with Lines.

 

[Swissmade]

Problem [SOLVED]