When to delete GDI objects, in particular, bitmaps

Question

I recently learned about the need to dispose of GDI objects because the GC does not care about them like other objects in C #. I have bitmaps that I would like to get throughout my life forms, but I'm not sure about some things ...

• When recreating a bitmap object, do I need to delete the original object first? I do not think, but I thought I would check. For instance:

  // Global
  Bitmap bmp;
  
  // In form constructor...
  bmp = new Bitmap(source);
  
  // In a function...
  if(bmp != null) {
    bmp.Dispose
    bmp = null
  }
  bmp = new Bitmap(source2);
  
  // On paint (if bmp not null)...
  DrawImage(bmp, rectangle);
  

• Since I want to save bitmaps for the life time of the form, can I just get rid of them in the form closing event?

• Is there a better alternative than saving raster images? Creating each bitmap from a file and removing paint is too slow. Using Image instead of Bitmap reduces image quality.

Thanks in advance!

Answer 1

• "Dispose". .
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Bitmap , using, :

using (Bitmap myBitmap = new Bitmap(src))
{
  //Do stuff with the temp bitmap
}