I'm trying the @Johan SchoemanCanvasView library, with which I make a drawing in an image, the theme is how I can save the image changes.
B4X:
Sub Globals
Private cv1 As CanvasView
Dim b As Bitmap
End Sub
Sub Activity_Create(FirstTime As Boolean)
Activity.LoadLayout("LayoutImageEdit")
b.Initialize(File.DirRootExternal & "/ImagenesAvl/","IMG_20178108230.jpg")
cv1.drawBitmap(b)
cv1.Mode = cv1.MODE_DRAW
cv1.PaintStrokeColor = Colors.Red
cv1.PaintStrokeWidth = 10
End Sub
Sub btnLimpiar_Click
cv1.undo
End Sub
Sub btnGuardar_Click
C.Initialize2(cv1.Bitmap)
Out = File.OpenOutput(File.DirRootExternal & "/ImagenesAvl/", "IMG_20178108230.jpg", False)
C.Bitmap.WriteToStream(Out, 100, "JPEG")
Out.Close
End Sub