COM

All COM objects are inherited from a common base class.

class IUnkown // abstract base class

{ public:

// get ptr to interface

virtual HRESULT __stdcall QueryInterface(<parms>) =0;

// inc object count

virtual ULONG __stdcall AddRef()=0;

// dec count & release obj resources

virtual ULONG __stdcall Release()=0;

}

// __stdcall forces parm onto the stack in right to left order

INTERFACES

IUnknown: baseclass w/vitual functions that get set to match your hardware at init.

IDirectDraw: represents the video card, sets video mode, interfaces to other modules

IDirectDrawSurface: represents video memory/drawing surface, but surfaces can also be created in main memory

IDirectDrawPallette: represents color palette associated with each drawing surface

IDirectDrawClipper: represents a DD clipper (a set of rectangles that DD can draw into), manages the clipping areas

Create a DD object

HRESULT DirectDrawCreateEx(<video id>,<ptr>,<NULL>);

returns DD_OK if it works, videoID = NULL selects curr driver

ptr = address of DD obj

LPDIRECTDRAW7 lpdd;

if (DirectDrawCreateEx(NULL, (void **)&lpdd, NULL) != DD_OK)

// ERROR

now lpdd->function(<parms>); calls DD functions

after you are done with the object you must de-allocate

lpdd->Release();

SET COPERATION LEVEL W/WINDOWS

HRESULT SetCooperativeLevel(<hWnd>, <flags>);

flags:

DDSCL_ALLOWMODEX	mode x (320X220 or 320X240) must be used w/full & exclusive
DDSCL_ALLOWREBOOT	allow ctr/alt/del in fullscreen
DDSCL_EXCLUSIVE	exclusive access, must be used w/fullscreen
DDSCL_FULLSCREEN	DD does whole screen w/o windows
DDSCL_NORMAL	act as a normal window
DDSCL_NOWINDOWSCHANGES	DD can’t minimize or restore app on activation

To do a fullscreen application:

lpdd->SetCooperativeLevel(hWnd, DDSCL_ALLOEMODEX | DDSCL_FULLSCREEN | DDSCLEXCLUSIVE | DDSCL_ALLOWREBOOT);

SETTING VIDEO MODE

lpdd->SetDisplayMode(<width>,<height>,<bits>,0,0);

bits is bits per pixel

if (lpdd->SetDisplayMode(640,480,8)!=DD_OK)

// ERROR

you can change video mode any time in a pgm, but avoid it

DDSurfaces

DD refers to displayable memory as surfaces.

· The Primary Surface is directly mapped to the video memory on the card (VRAM).

· Surfaces can be any size but the primary must be same as the resolution in use.

· Can create in RAM or VRAM

· All surfaces have the same depth & color properties as the primary.

Typical windows program has

· Primary surface

· Secondary surface – backBuffer for animation

· Offscreen surfaces – hold bitmaps or sprites for fast display

Complete Example:

// Creates a DirectDraw object and changes display

// INCLUDES

#define WINDOWS_LEAN_AND_MEAN

#include <windows.h> // include important windows stuff

#include <windowsx.h>

#include <mmsystem.h>

#include <iostream.h> // include important C/C++ stuff

#include <conio.h>

#include <stdlib.h>

#include <malloc.h>

#include <memory.h>

#include <string.h>

#include <stdarg.h>

#include <stdio.h>

#include <math.h>

#include <io.h>

#include <fcntl.h>

#include <ddraw.h> // directX includes

// DEFINES

// defines for windows

#define WINDOW_CLASS_NAME "WINXCLASS" // class name

#define WINDOW_WIDTH 320 // size of window

#define WINDOW_HEIGHT 200

// MACROS

// these read the keyboard asynchronously

#define KEY_DOWN(vk_code)((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)

#define KEY_UP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1)

// PROTOTYPES

int GameInit(void *parms=NULL);

int GameShutdown(void *parms=NULL);

int GameMain(void *parms=NULL);

// GLOBALS

HWND mainWindowHandle = NULL; // save the window handle

HINSTANCE mainInstance = NULL; // save the instance

char buffer[80]; // used to print text

LPDIRECTDRAW lpdd; // pointer to direct draw object

// FUNCTIONS

LRESULT CALLBACK WindowProc(HWND hwnd,UINT msg,

WPARAM wparam, LPARAM lparam)

{ // this is the main message handler of the system

PAINTSTRUCT ps; // used in WM_PAINT

HDC hdc; // handle to a device context

// what is the message

switch(msg)

{ case WM_CREATE:

{ // do initialization stuff here

return(0);

} break;

case WM_PAINT:

{ // start painting

hdc = BeginPaint(hwnd,&ps);

// end painting

EndPaint(hwnd,&ps);

return(0);

} break;

case WM_DESTROY:

{ // kill the application

PostQuitMessage(0);

return(0);

} break;

default:break;

} // end switch

// process any messages that we didn't take care of

return (DefWindowProc(hwnd, msg, wparam, lparam));

} // end WinProc

// *************** WINMAIN ****************

int WINAPI WinMain(HINSTANCE hinstance,HINSTANCE hprevinstance,

LPSTR lpcmdline, int ncmdshow)

{ WNDCLASS winclass; // this will hold the class we create

HWND hwnd; // generic window handle

MSG msg; // generic message

HDC hdc; // generic dc

PAINTSTRUCT ps; // generic paintstruct

// first fill in the window class stucture

winclass.style = CS_DBLCLKS | CS_OWNDC |

CS_HREDRAW | CS_VREDRAW;

winclass.lpfnWndProc = WindowProc;

winclass.cbClsExtra = 0;

winclass.cbWndExtra = 0;

winclass.hInstance = hinstance;

winclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);

winclass.hCursor = LoadCursor(NULL, IDC_ARROW);

winclass.hbrBackground = GetStockObject(BLACK_BRUSH);

winclass.lpszMenuName = NULL;

winclass.lpszClassName = WINDOW_CLASS_NAME;

// register the window class

if (!RegisterClass(&winclass))

return(0);

// create the window

if (!(hwnd = CreateWindow(WINDOW_CLASS_NAME, "WinX Game Console",

WS_OVERLAPPEDWINDOW | WS_VISIBLE, 0,0, WINDOW_WIDTH,

WINDOW_HEIGHT, NULL, NULL, hinstance, NULL)))

return(0);

// save the window handle and instance in a global

mainWindowHandle = hwnd;

mainInstance = hinstance;

// perform all game console specific initialization

GameInit();

// enter main event loop

while(1)

{

if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))

{ // test if this is a quit

if (msg.message == WM_QUIT)

break;

// translate any accelerator keys

TranslateMessage(&msg);

// send the message to the window proc

DispatchMessage(&msg);

} // end if

// main game processing goes here

GameMain();

} // end while

// shutdown game and release all resources

GameShutdown();

// return to Windows like this

return(msg.wParam);

} // end WinMain

// WINX GAME PROGRAMMING CONSOLE FUNCTIONS

int GameInit(void *parms)

{ // this function is where you do all the initialization

// for your game

// create object and test for error

if (DirectDrawCreate(NULL,&lpdd,NULL)!=DD_OK)

return(0);

// set cooperation level to windowed mode normal

if ((lpdd->SetCooperativeLevel(mainWindowHandle,

DDSCL_ALLOWMODEX | DDSCL_FULLSCREEN |

DDSCL_EXCLUSIVE | DDSCL_ALLOWREBOOT))!=DD_OK)

return(0);

// set the display mode

if ((lpdd->SetDisplayMode(640,480,8))!=DD_OK)

return(0);

// return success

return(1);

} // end GameInit

int GameShutdown(void *parms)

{ // this function is where you shutdown your game and

// release all resources that you allocated

// release the directdraw object

if (lpdd!=NULL)

lpdd->Release();

// return success

return(1);

} // end GameShutdown

int GameMain(void *parms)

{ // check of user is trying to exit

if (KEY_DOWN(VK_ESCAPE) || KEY_DOWN(VK_SPACE))

PostMessage(mainWindowHandle, WM_DESTROY,0,0);

// return success

return(1);

} // end GameMain