Why should I do manual double buffering?

Question

I am working on a game in C# (either 2.0 or 3.5 havn't decided yet). The game will be played on a map with a hexagonal grid. I appreciate that the UI for this map should use double buffering (lots of layers, so slow drawing). I know that I can enable double buffering through a style, or create my own buffer and handle it myself. Most recomendations I find on the web are to handle it yourself. I am wondering why? Obviously this allows me to avoid the assumptions that are inherent in the control double buffering, but I do not know what those assumptions are.

Again, I am not looking for code to explain how to double buffer my control, but rather why I would build this myself instead of using the double buffering style and allowing the CLR/Control class to handle it?

Answer 1

From MS:

For graphically intensive applications such as animation, you can sometimes improve performance by using a dedicated BufferedGraphicsContext instead of the BufferedGraphicsContext provided by the BufferedGraphicsManager. This enables you to create and manage graphics buffers individually, without incurring the performance overhead of managing all the other buffered graphics associated with your application, though the memory consumed by the application will be greater.

EDIT: I also found this article from Bob Powell which may be helpful:

Manual double buffering can be useful if you don't want the system so make assumptions for you such as whether the background is opaque or transparent or perhaps if you want to create a more complex buffering system. There are a few simple rules that you need to follow to get manual double buffering right.

First, don’t create a new back-buffer every draw cycle. Only create or destroy the bitmap when the window's client size changes. Second, only create a bitmap of the size you need. Clearing pixels takes time and so if there are more pixels than you need, you're just wasting processor cycles. Lastly, use the simplest draw method to copy the bitmap to the screen. DrawImageUnscaled is the way to go here.

EDIT: Another reason is that you may want the application to control buffering, not the controls themselves.

Source: Pro .NET 2.0 Windows Forms and custom controls in C#.