C语言实现黑客帝国绿色字流效果

#include <windows.h>

#define ID_TIMER    1
#define STRMAXLEN  25 //一个显示列的最大长度
#define STRMINLEN  8  //一个显示列的最小长度

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
typedef struct tagCharChain //整个当作屏幕的一个显示列,这是个双向列表
{
        struct tagCharChain *prev; //链表的前个元素
        TCHAR  ch;                  //一个显示列中的一个字符
        struct tagCharChain *next; //链表的后个元素
}CharChain, *pCharChain;

typedef struct tagCharColumn
{
        CharChain *head, *current, *point;
        int x, y, iStrLen; //显示列的开始显示的x,y坐标,iStrLen是这个列的长度
        int iStopTimes, iMustStopTimes; //已经停滞的次数和必须停滞的次数,必须停滞的次数是随机的
}CharColumn, *pCharColumn;

int main(HINSTANCE hInstance, HINSTANCE hPrevInstance,PSTR szCmdLine, int iCmdShow)
{
        static TCHAR szAppName[] = TEXT ("matrix") ;
        HWND            hwnd ;
        MSG            msg ;
        WNDCLASS    wndclass ;

        wndclass.style                = CS_HREDRAW | CS_VREDRAW ;

        wndclass.lpfnWndProc        = WndProc ;
        wndclass.cbClsExtra        = 0 ;
        wndclass.cbWndExtra        = 0 ;
        wndclass.hInstance        = hInstance ; 
 
        wndclass.hIcon                = LoadIcon (NULL, IDI_APPLICATION) ;
        wndclass.hCursor        = LoadCursor (NULL, IDC_ARROW) ;
        wndclass.hbrBackground        = (HBRUSH) GetStockObject (BLACK_BRUSH) ;
        wndclass.lpszMenuName        = NULL ;
        wndclass.lpszClassName        = szAppName ;

        if(!RegisterClass (&wndclass))
        {
            MessageBox (NULL, TEXT ("此程序必须运行在NT下!"), szAppName, MB_ICONERROR) ;
            return 0;
        }

        hwnd = CreateWindow (szAppName, NULL,
                            WS_DLGFRAME | WS_THICKFRAME | WS_POPUP,
                            0, 0,
                            GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN),
                            NULL, NULL, hInstance,
                            NULL) ;

        ShowWindow (hwnd, SW_SHOWMAXIMIZED) ; //最大化显示
        UpdateWindow (hwnd) ;
        ShowCursor(FALSE); //隐藏鼠标光标
        
        srand ((int) GetCurrentTime ()) ; //初始化随机数发生器
        while (GetMessage (&msg, NULL, 0, 0))