双缓存技术在 Symbian 中的实现

核心提示：This is a bitmap to which the window server already has a handle. Functionswhich take a window server bitmap are faster than equivalent functions whichtake a CF

This is a bitmap to which the window server already has a handle. Functions

which take a window server bitmap are faster than equivalent functions which

take a CFbsBitmap.

2) iBufDevice为CFbsBitmapDevice类型的对象，CFbsBitmapDevice的官方解释可以简单的理解为管理文字和位图的图形设备：

A graphics device to which a bitmap managed by the font and bitmap server can be drawn.

3) iBufGc为CBitmapContext类型的对象，即位图对象的设备上下文dc，获取了iBufGc后，可以使用CBitmapContext中的方法对位图进行绘制。