TOTWGPG

Brian Jones · 2001-12-12T22:31:28

Hello, I am at the latter part of the second chapter in this book. I've made a program that opens two different windows, based on two different classes. // Two Windows.cpp : Defines the entry point for the application. // DEMO2_5.CPP - Creates two windows based on the same // window class // INCLUDES /////////////////////////////////////////////// #define WIN32_LEAN_AND_MEAN // just say no to MFC #include <windows.h> // include all the windows headers #include <windowsx.h> // include useful macros #include <stdio.h> #include <math.h> #include <stdafx.h> // DEFINES //////////////////////////////////////////////// // defines for windows #define WINDOW_CLASS_NAME "WINCLASS1" #define WINDOW_CLASS_NAME2 "WINCLASS2" // GLOBALS //////////////////////////////////////////////// HWND hWindow1 = NULL; HWND hWindow2 = NULL; // 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 success return(0); } break; case WM_PAINT: { // simply validate the window hdc = BeginPaint(hwnd,&ps); // you would do all your painting here EndPaint(hwnd,&ps); // return success return(0); } break; case WM_DESTROY: { // kill the application, this sends a WM_QUIT message if( hwnd == hWindow1 ) hWindow1 = NULL; if( hwnd == hWindow2 ) hWindow2 = NULL; if((!hWindow1) && (!hWindow2) ) PostQuitMessage(0); // return success 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) { WNDCLASSEX winclass; // this will hold the class we create WNDCLASSEX winclass2; MSG msg; // generic message // first fill in the window class stucture winclass.cbSize = sizeof(WNDCLASSEX); 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 = (HBRUSH)GetStockObject(BLACK_BRUSH); winclass.lpszMenuName = NULL; winclass.lpszClassName = WINDOW_CLASS_NAME; winclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION); // winclass2 struct winclass2.cbSize = sizeof(WNDCLASSEX); winclass2.style = CS_DBLCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW; winclass2.lpfnWndProc = WindowProc; winclass2.cbClsExtra = 0; winclass2.cbWndExtra = 0; winclass2.hInstance = hinstance; winclass2.hIcon = LoadIcon(NULL, IDI_APPLICATION); winclass2.hCursor = LoadCursor(NULL, IDC_ARROW); winclass2.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); winclass2.lpszMenuName = NULL; winclass2.lpszClassName = WINDOW_CLASS_NAME2; winclass2.hIconSm = LoadIcon(NULL, IDI_APPLICATION); // register the window class if (!RegisterClassEx(&winclass)) return(0); // register the window2 class if (!RegisterClassEx(&winclass2)) return(0); // create the first window if (!(hWindow1 = CreateWindowEx(NULL, // extended style WINDOW_CLASS_NAME, // class "Window 1 Based on WINCLASS1", // title WS_OVERLAPPEDWINDOW | WS_VISIBLE, 0,0, // initial x,y 400,400, // initial width, height NULL, // handle to parent NULL, // handle to menu hinstance,// instance of this application NULL))) // extra creation parms return(0); // create the second window if (!(hWindow2 = CreateWindowEx(NULL, // extended style WINDOW_CLASS_NAME2, // class "Window 2 Based on WINCLASS2", // title WS_OVERLAPPEDWINDOW | WS_VISIBLE, 100,100, // initial x,y 400,400, // initial width, height NULL, // handle to parent NULL, // handle to menu hinstance,// instance of this application NULL))) // extra creation parms return(0); // enter main event loop, but this time we use PeekMessage() // instead of GetMessage() to retrieve messages while(TRUE) { // test if there is a message in queue, if so get it 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 } // end while // return to Windows like this return(msg.wParam); } // end WinMain /////////////////////////////////////////////////////////// It executes perfectly, but I'm not sure how WindowProc works. How does it know which window need to be repainted? I'm my code, it doesn't appear to know the handle of either window. Somebody please help so I can move on to the next chapter. Edited by - Brian Jones on December 12, 2001 5:24:02 PM Edited by - Brian Jones on December 12, 2001 5:28:01 PM

For Beginners

Started by Brian Jones December 12, 2001 04:16 PM

9 comments, last by Brian Jones 22 years, 4 months ago

Oluseyi

2,123

December 12, 2001 10:31 PM

quote:Original post by Brian Jones
I still don''t get it. Do that handle to a window point to NULL when a WM_DESTROY message is sent to that window?

You need to pay attention to what you read.

Can you see where hWindow1

or hWindow2 is set to NULL? And then the code checks to see if they are both NULL?

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Thanks to Kylotan for the idea!

TOTWGPG

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