一个不完整的总结性程序

int Game_Init(void *parms = NULL, int num_parms = 0)
{
// this is called once after the initial window is created and
// before the main event loop is entered, do all your initialization
// here

// create IDirectDraw interface 7.0 object and test for error   创建DirectDraw主对象
if (FAILED(DirectDrawCreateEx(NULL, (void **)&lpdd, IID_IDirectDraw7, NULL)))
   return(0);

// set cooperation to full screen
if (FAILED(lpdd->SetCooperativeLevel(main_window_handle,
                                      DDSCL_FULLSCREEN | DDSCL_ALLOWMODEX |
                                      DDSCL_EXCLUSIVE | DDSCL_ALLOWREBOOT)))
   {
   // error
   return(0);
   } // end if

// set display mode to 640x480x8
if (FAILED(lpdd->SetDisplayMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP,0,0)))
   {
   // error
   return(0);
   } // end if

// clear ddsd and set size
memset(&ddsd,0,sizeof(ddsd));
ddsd.dwSize = sizeof(ddsd);

// enable valid fields
ddsd.dwFlags = DDSD_CAPS;

// request primary surface
ddsd.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE;

// create the primary surface    创建主显示表面
if (FAILED(lpdd->CreateSurface(&ddsd, &lpddsprimary, NULL)))
   {
   // error
   return(0);
   } // end if

// build up the palette data array  初始化调色板
for (int color=1; color < 255; color++)
    {
    // fill with random RGB values
    palette[color].peRed   = rand()%256;
    palette[color].peGreen = rand()%256;
    palette[color].peBlue  = rand()%256;

    // set flags field to PC_NOCOLLAPSE
    palette[color].peFlags = PC_NOCOLLAPSE;
    } // end for color

// now fill in entry 0 and 255 with black and white
palette[0].peRed   = 0;
palette[0].peGreen = 0;
palette[0].peBlue  = 0;
palette[0].peFlags = PC_NOCOLLAPSE;

palette[255].peRed   = 255;
palette[255].peGreen = 255;
palette[255].peBlue  = 255;
palette[255].peFlags = PC_NOCOLLAPSE;

// create the palette object
if (FAILED(lpdd->CreatePalette(DDPCAPS_8BIT | DDPCAPS_ALLOW256 |
                                DDPCAPS_INITIALIZE,
                                palette,&lpddpal, NULL)))
{
// error
return(0);
} // end if

// finally attach the palette to the primary surface  调色板与主表面关联
if (FAILED(lpddsprimary->SetPalette(lpddpal)))
    {
    // error
    return(0);
    } // end if

// return success or failure or your own return code here
return(1);

} // end Game_Init

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

int Game_Main(void *parms = NULL, int num_parms = 0)
{
// this is the main loop of the game, do all your processing
// here

// for now test if user is hitting ESC and send WM_CLOSE
if (KEYDOWN(VK_ESCAPE))
   SendMessage(main_window_handle,WM_CLOSE,0,0);

// plot 1000 random pixels to the primary surface and return
// clear ddsd and set size, never assume it's clean
memset(&ddsd,0,sizeof(ddsd));
ddsd.dwSize = sizeof(ddsd);

/////获取对内存的控制权限

if (FAILED(lpddsprimary->Lock(NULL, &ddsd,
                   DDLOCK_SURFACEMEMORYPTR | DDLOCK_WAIT,
                   NULL)))
   {
   // error
   return(0);
   } // end if

// now ddsd.lPitch is valid and so is ddsd.lpSurface

// make a couple aliases to make code cleaner, so we don't
// have to cast
int mempitch        = (int)ddsd.lPitch;
UCHAR *video_buffer = (UCHAR *)ddsd.lpSurface;

// plot 1000 random pixels with random colors on the
// primary surface, they will be instantly visible
for (int index=0; index < 1000; index++)      //////绘制像素
    {
    // select random position and color for 640x480x8
    UCHAR color = rand()%256;
    int x = rand()%640;
    int y = rand()%480;

    // plot the pixel
    video_buffer[x+y*mempitch] = color; //////说明color是系统硬件那个调色板的索引      

    } // end for index

// now unlock the primary surface
if (FAILED(lpddsprimary->Unlock(NULL)))
   return(0);

// sleep a bit
Sleep(30);

// return success or failure or your own return code here
return(1);

} // end Game_Main

////////////////////////////////////////////////////////////清理原则：后创建的指针先释放

int Game_Shutdown(void *parms = NULL, int num_parms = 0)
{
// this is called after the game is exited and the main event
// loop while is exited, do all you cleanup and shutdown here

// first the palette
if (lpddpal)
   {
   lpddpal->Release();
   lpddpal = NULL;
   } // end if

// now the primary surface
if (lpddsprimary)
   {
   lpddsprimary->Release();
   lpddsprimary = NULL;
   } // end if

// now blow away the IDirectDraw4 interface
if (lpdd)
   {
   lpdd->Release();
   lpdd = NULL;
   } // end if

// return success or failure or your own return code here
return(1);

} // end Game_Shutdown