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January 28th, 2013, 08:52 AM
#1
Error in registering windowsclass
The following code it taken from msdn library but it is failing to compile.
the following code has a header where all the variables used here are stored in header App.h.
please help me with this, i cannot really go further without this problem resolved.
The following lines are giving trouble:
Code:
DialogBox(pApp->getInstance(), MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, pApp->About);
error: 'App::About': function call missing argument list; use '&App::About' to create a pointer to member
Code:
wcex.lpfnWndProc = &App::WndProc;
error: '=' : cannot convert from 'LRESULT (__stdcall App::* )(HWND,UINT,WPARAM,LPARAM)' to 'WNDPROC'
There is no context in which this conversion is possible
(Removing &did not help)
Here is the complete code:
Code:
#include "stdafx.h"
#include "App.h"
App::App(void)
{
}
App::~App(void)
{
}
//Initializing variables
BOOL App::Init(HINSTANCE hInstance, int cmd)
{
hInst = hInstance; // Store instance handle in our global variable
// Initialize global strings
LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadString(hInstance, IDC_FIRSTPAINT, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
// Perform application initialization:
if (!InitInstance (cmd))
{
return FALSE;
}
return true;
}
// FUNCTION: InitInstance(HINSTANCE, int)
//
// PURPOSE: Saves instance handle and creates main window
//
// COMMENTS:
//
// In this function, we save the instance handle in a global variable and
// create and display the main program window.
//
BOOL App::InitInstance(int nCmdShow)
{
HWND hWnd;
hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInst, this);
if (!hWnd)
{
return FALSE;
}
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
//Function to run the message loop for the class
int App::RunMessageLoop()
{
MSG msg;
HACCEL hAccelTable;
hAccelTable = LoadAccelerators(hInst, MAKEINTRESOURCE(IDC_FIRSTPAINT));
// Main message loop:
while (GetMessage(&msg, NULL, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int) msg.wParam;
}
//
// FUNCTION: MyRegisterClass()
//
// PURPOSE: Registers the window class.
//
ATOM App::MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEX wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = &App::WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInst;
wcex.hIcon = LoadIcon(hInst, MAKEINTRESOURCE(IDI_FIRSTPAINT));
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCE(IDC_FIRSTPAINT);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassEx(&wcex);
}
//
// FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
// PURPOSE: Processes messages for the main window.
//
// WM_COMMAND - process the application menu
// WM_PAINT - Paint the main window
// WM_DESTROY - post a quit message and return
//
//
LRESULT CALLBACK App::WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
App* pApp;
if (message == WM_CREATE)
{
LPCREATESTRUCT pcs = (LPCREATESTRUCT)lParam;
pApp = (App *)pcs->lpCreateParams;
::SetWindowLongPtrW(hWnd,GWLP_USERDATA,PtrToUlong(pApp));
return TRUE;
}
else
{
pApp = reinterpret_cast<App *>(static_cast<LONG_PTR>(::GetWindowLongPtrW(hWnd,GWLP_USERDATA)));
if (!pApp)
return DefWindowProc(hWnd, message, wParam, lParam);
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
switch (message)
{
case WM_COMMAND:
wmId = LOWORD(wParam);
wmEvent = HIWORD(wParam);
// Parse the menu selections:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(pApp->getInstance(), MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, pApp->About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
break;
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code here...
EndPaint(hWnd, &ps);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
}
// Message handler for about box.
INT_PTR CALLBACK App::About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(lParam);
switch (message)
{
case WM_INITDIALOG:
return (INT_PTR)TRUE;
case WM_COMMAND:
if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
{
EndDialog(hDlg, LOWORD(wParam));
return (INT_PTR)TRUE;
}
break;
}
return (INT_PTR)FALSE;
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