DSA and RBackupWindow铪铪铪

         DSA和RBackupWindow是Symbian中的两种屏幕画图方法,但是它们之间到底有什么区别呢?各自的优点和缺点又是什么呢?我们在写程序的时候该如何取舍呢? 
        下面是我从Nokia Forum上摘录下来的观点:
①

        RBackupWindow is for fast graphics which do not need to be updated when other windows are overlapping. Does not need to be full screen as this is a window, which is used as framebuffer. Almost as fast as direct fraw with CFbsScreenDevice. All drawing can be done to CFbsBitmap, which gives some freedom to use different draw methods, Fast and safe way to draw to screen if used correctly( needs a trick with thread priorities). Automatically fills drawbuffer regions to screen when obstructing windows disappear.

         The 2D example on the forum nokia is also using the RBackupWindow.
         I never used DSA but I think most of the people are using this method to draw. Any expert on this can give any advices?
         译文:RBackupWindow是一种当其它窗口覆盖时不需要更新的快速图形画法.作为一个framebuffer,这个窗口不需要全屏显示.几乎和DSA一样快速.
②
       做为Symbian游戏的两个比较经典的例子程序:FrozenBubble和Example2D
       FrozenBubble用DSA做为屏幕画法,而Example2D却用RBackupWindow做为屏幕画法.而事实上运行这两个游戏,并没感觉到其中速度有明显的差别.既然没差别,Symbian为什么要搞出来这两个屏幕画法.实在是搞不清楚.