Android Question To erase drown lines on the preview image

[Urishev]

Hello! How to erase drawn lines on the preview image of the camera?
Here is the code:
Sub Camera1_Preview (PreviewPic() AsByte)
'get the preview image
IfDateTime.Now > lastPreviewSaved + IntervalMs Then
Dim jpeg() AsByte = camEx.PreviewImageToJpeg(PreviewPic, 70)
lastPreviewSaved = DateTime.Now
DiminAsInputStream
in.InitializeFromBytesArray(jpeg, 0, jpeg.Length)
bmp1.Initialize2(in)
in.Close
EndIf

'draw the line
Dim cvs1 AsCanvas
Dim img1 AsImageView
img1.Initialize (bmp1)
Activity.AddView (img1,0%x,0%y,100%x,100%y)
cvs1.Initialize(img1)
cvs1.DrawLine((X1,Y1,X2,Y2, Colors.Blue,2dip)
EndSub

'to erase drawn line?

 

[Erel]

Please use [code]code here...[/code] tags when posting code.

What exactly are you trying to implement?

 

[Urishev]

I want to draw and erase lines on the camera image preview.
To draw it turns out, to erase - no.
When there is a ordinary image to erase lines by using the reboot the image (img.Bitmap = LoadBitmap(...)
In this case, the image is a camera preview.
How to erase drawn lines on the preview image of the camera?

 

[wonder]

To my knowledge, you can't erase anything that has been drawn in the Canvas...
By the way, the canvas is sloooooow, better to use a LibGDX (or any other OpenGL) transparent surface over the camera preview.

If you need me to elaborate further on how to construct such an algorithm, just let me know.

 

[Erel]

Your code looks wrong. Are you creating a new canvas for each preview frame? You will run out memory.

The simplest way to draw and erase is to use two layers. Draw the bitmap on one layer and make the drawings on a layer above it. This way you will be able to erase drawings.

 

[Urishev]

Thank you, the hint understood, I will try.

 

[Urishev]

Thanks again! Did it!
The “technical” answer to my problem found in example SourceCode/Layers.

 

[klaus]

The “technical” answer to my problem found in example SourceCode/Layers.

It seems worth spending time to read the Guides (the B4A User's Guide in this case).

 

[Urishev]

Why not change the picture size? Use CameraExClass
Sub Camera1_Ready (Success As Boolean)
If Success Then
camEx.StartPreview
camEx.SetPictureSize(800, 600)
camEx.CommitParameters
Else
ToastMessageShow("Cannot open camera.", True)
End If
End Sub
What's wrong?

 

[Erel]

Please start a new thread for a new question.