QUERY.CPP
/*
* QUERY.CPP
* Demonstration of QueryInterface and different techniques to
* implement multiple interfaces.
*
* Copyright (c)1993-1995 Microsoft Corporation, All Rights Reserved
*
* Kraig Brockschmidt, Microsoft
* Internet : kraigb@microsoft.com
* Compuserve: >INTERNET:kraigb@microsoft.com
*/
#define INITGUIDS
#include <windows.h>
#include "query.h"
/*
* WinMain
*
* Purpose:
* Main entry point of application.
*/
int PASCAL WinMain(HINSTANCE hInst, HINSTANCE hInstPrev
, LPSTR pszCmdLine, int nCmdShow)
{
MSG msg;
PAPP pApp;
pApp=new CApp(hInst, hInstPrev, nCmdShow);
if (NULL==pApp)
return -1;
if (pApp->Init())
{
while (GetMessage(&msg, NULL, 0,0 ))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
delete pApp;
return msg.wParam;
}
/*
* QueryWndProc
*
* Purpose:
* Standard window class procedure.
*/
LRESULT APIENTRY QueryWndProc(HWND hWnd, UINT iMsg, WPARAM wParam
, LPARAM lParam)
{
PAPP pApp;
HRESULT hr;
BOOL fRes;
ISampleOne *pISampleOne;
ISampleTwo *pISampleTwo;
const UINT CCHTEMP=80;
TCHAR szTemp[CCHTEMP];
COMMANDPARAMS(wID, wCode, hWndMsg);
pApp=(PAPP)GetWindowLong(hWnd, QUERYWL_STRUCTURE);
switch (iMsg)
{
case WM_NCCREATE:
pApp=(PAPP)(((LPCREATESTRUCT)lParam)->lpCreateParams);
SetWindowLong(hWnd, QUERYWL_STRUCTURE, (LONG)pApp);
return (DefWindowProc(hWnd, iMsg, wParam, lParam));
case WM_DESTROY:
PostQuitMessage(0);
break;
case WM_COMMAND:
switch (wID)
{
case IDM_OBJECTCREATE1:
if (NULL!=pApp->m_pIUnknown)
pApp->m_pIUnknown->Release();
fRes=CreateObject1(&pApp->m_pIUnknown);
pApp->Message(fRes ? TEXT("Object 1 created")
: TEXT("Object 1 creation failed"));
break;
case IDM_OBJECTCREATE2:
if (NULL!=pApp->m_pIUnknown)
pApp->m_pIUnknown->Release();
fRes=CreateObject2(&pApp->m_pIUnknown);
pApp->Message(fRes ? TEXT("Object 2 created")
: TEXT("Object 2 creation failed"));
break;
case IDM_OBJECTCREATE3:
if (NULL!=pApp->m_pIUnknown)
pApp->m_pIUnknown->Release();
fRes=CreateObject3(&pApp->m_pIUnknown);
pApp->Message(fRes ? TEXT("Object 3 created")
: TEXT("Object 3 creation failed"));
break;
case IDM_OBJECTRELEASE:
if (NULL==pApp->m_pIUnknown)
{
pApp->Message(TEXT("There is no object"));
break;
}
if (0==pApp->m_pIUnknown->Release())
{
pApp->m_pIUnknown=NULL;
pApp->Message(TEXT("Object released"));
}
break;
case IDM_OBJECTGETMESSAGE:
if (NULL==pApp->m_pIUnknown)
{
pApp->Message(TEXT("There is no object"));
break;
}
hr=pApp->m_pIUnknown->QueryInterface
(IID_ISampleOne, (PPVOID)&pISampleOne);
if (FAILED(hr))
{
pApp->Message(TEXT("Failed to get ISampleOne"));
break;
}
hr=pISampleOne->GetMessage(szTemp, CCHTEMP);
pApp->Message(SUCCEEDED(hr) ? szTemp
: TEXT("ISampleOne::GetMessage failed"));
//m_pIUnknown is still valid after this Release
pISampleOne->Release();
break;
case IDM_OBJECTGETSTRING:
if (NULL==pApp->m_pIUnknown)
{
pApp->Message(TEXT("There is no object"));
break;
}
hr=pApp->m_pIUnknown->QueryInterface
(IID_ISampleTwo, (PPVOID)&pISampleTwo);
if (FAILED(hr))
{
pApp->Message(TEXT("Failed to get ISampleTwo"));
break;
}
hr=pISampleTwo->GetString(szTemp, CCHTEMP);
pApp->Message(SUCCEEDED(hr) ? szTemp
: TEXT("ISampleTwp::GetString failed"));
//m_pIUnknown is still valid after this Release
pISampleTwo->Release();
break;
case IDM_OBJECTEXIT:
PostMessage(hWnd, WM_CLOSE, 0, 0L);
break;
}
break;
default:
return (DefWindowProc(hWnd, iMsg, wParam, lParam));
}
return 0L;
}
/*
* CApp::CApp
* CApp::~CApp
*
* Constructor Parameters:
* hInst HINSTANCE of the Application from WinMain
* hInstPrev HINSTANCE of a previous instance from WinMain
* nCmdShow UINT specifying how to show the app window,
* from WinMain.
*/
CApp::CApp(HINSTANCE hInst, HINSTANCE hInstPrev
, UINT nCmdShow)
{
//Initialize WinMain parameter holders.
m_hInst =hInst;
m_hInstPrev =hInstPrev;
m_nCmdShow =nCmdShow;
m_hWnd=NULL;
m_pIUnknown=NULL;
return;
}
CApp::~CApp(void)
{
//Release the object if we still have it.
ReleaseInterface(m_pIUnknown);
return;
}
/*
* CApp::Init
*
* Purpose:
* Initializes an CApp object by registering window classes,
* creating the main window, and doing anything else prone to
* failure. If this function fails the caller should guarantee
* that the destructor is called.
*
* Parameters:
* None
*
* Return Value:
* BOOL TRUE if successful, FALSE otherwise.
*/
BOOL CApp::Init(void)
{
WNDCLASS wc;
if (!m_hInstPrev)
{
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = QueryWndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = CBWNDEXTRA;
wc.hInstance = m_hInst;
wc.hIcon = LoadIcon(m_hInst, TEXT("Icon"));
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wc.lpszMenuName = MAKEINTRESOURCE(IDR_MENU);
wc.lpszClassName = TEXT("QUERY");
if (!RegisterClass(&wc))
return FALSE;
}
m_hWnd=CreateWindow(TEXT("QUERY"), TEXT("QueryInterface Demo")
, WS_MINIMIZEBOX | WS_OVERLAPPEDWINDOW
,35, 35, 350, 250, NULL, NULL, m_hInst, this);
if (NULL==m_hWnd)
return FALSE;
ShowWindow(m_hWnd, m_nCmdShow);
UpdateWindow(m_hWnd);
return TRUE;
}
/*
* CApp::Message
*
* Purpose:
* Displays a message in the client area of the window. This is
* just to centralize the call to simpify other code.
*
* Parameters:
* psz LPTSTR to the string to display.
*
* Return Value:
* None
*/
void inline CApp::Message(LPTSTR psz)
{
HDC hDC;
RECT rc;
hDC=GetDC(m_hWnd);
GetClientRect(m_hWnd, &rc);
SetBkColor(hDC, GetSysColor(COLOR_WINDOW));
SetTextColor(hDC, GetSysColor(COLOR_WINDOWTEXT));
/*
* We'll just be sloppy and clear the whole window as
* well as write the string with one ExtTextOut call.
* No word wrapping here...
*/
ExtTextOut(hDC, 0, 0, ETO_OPAQUE, &rc, psz, lstrlen(psz), NULL);
ReleaseDC(m_hWnd, hDC);
return;
}