NewImage = OldImage overwrites old image

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Private ReadOnly oldimage As Image = .....

Private Sub drawnewimage()
Dim newimage As Image = oldimage
*Draw over newimage*
End Sub

*Display old image*
The old image gets overwritten. How do copy instead of overwrite?

Posted 14-Aug-15 18:36pm

StanGertrudeMeier

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Sergey Alexandrovich Kryukov · Accepted Answer · 2015-08-14T18:48:00

The question makes little sense because it is based on not understanding one of the most fundamental concept, reference types. Assignment copies references, not objects themselves. You don't "overwrite" anything, you just copy reference to the same object and then modify the same object.

What you want is called cloning. Please see, for example, https://msdn.microsoft.com/en-us/library/system.drawing.image.clone%28v=vs.110%29.aspx[^].

However, understanding the problem is much more important than the solution, including this trivial solution. First of all, you should understand clearly what happens in your example. Be careful: you cannot really successfully do any programming before you perfectly understand reference and value types, and probably a lot more.

—SA