Using-SyncUpdateDC-to-Reduce-Screen-Flicker.md

@@ -34,22 +34,32 @@ Generally, we can use one of the following ways to eliminate this flicker:
    same as the first method.
 1. Use the new synchronous update mechanism introduced in MiniGUI 3.2.x.
 
-This documents describes how to use the synchronous update mechanism to
-reduce the screen flicker.
+This documents describes how to use the new synchronous update mechanism
+to reduce the screen flicker.
 
 ## Principle
 
+Essentially, the new synchronous update mechanism uses a shadow frame
+buffer for MiniGUI, and refresh the content that needs to be updated to
+the screen at one time, by calling `SyncUpdateDC` function.
+
+In this way, we do not need to create and destroy memory DC frequently,
+so we will get a certain degree of performance improvement.
+And the MiniGUI app's code can keep as simple as possible.
+In other words, we can improve the maintainability of the code as well.
 
 ## Usage
 
 - Including option `--enable-syncupdate` when configuring MiniGUI.
-- Using a shadow NEWGAL engine and implementing `UpdateRects` method
+- Using a shadow-like NEWGAL engine and implementing `UpdateRects` method
   of your NEWGAL engine to update the dirty regions to your real
   screen frame buffer.
 - Calling `SyncUpdateDC(HDC_SCREEN)` when you want to update the
   screen. Generally, you can call this function after calling `EndPaint`
   function when handling `MSG_PAINT` message.
 
+## Sample
+
 ## Restrictions
 
 The synchronous update mechanism provides an easy way to reduce