为什么不直接用窗口过程函数，而用DispatchMessage()

[Felix常温]

在消息循环中，dispatchmessage()的功能是调用窗口过程函数，但为什么不直接写窗口过程函数呢，是不是还有其它用处！！请高手解怎么答！

[zyq5945]

dispatchmessage()的在这个地方直接调用函数是可以的，这样设计估计就是面向对象的思想，一个部分作一件事，一个部分负责一个功能，尽量不要牵扯到其他部分的功能。

#include <Windows.h>
#include <stdio.h>

LRESULT CALLBACK WinSunProc(HWND hwnd,UINT uMsg,WPARAM wParam,LPARAM lParam);
HWND hwnd;

void WMBUTTON()
{
					
	MessageBox(hwnd,"mouse clicked","message",MB_ICONINFORMATION);
	HDC hdc;
	hdc = GetDC(hwnd);
	TextOut(hdc,0,0,"http://www.sunxin.org",strlen("http://www.sunxin.org"));
	ReleaseDC(hwnd,hdc);

}

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpcmdLine,int nShowCmd)
{
	WNDCLASS wndcls;
	
	wndcls.cbClsExtra = 0;
	wndcls.cbWndExtra = 0;
	wndcls.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
	wndcls.hCursor = LoadCursor(NULL,MAKEINTRESOURCE(IDC_CROSS));
	wndcls.hIcon = LoadIcon(NULL,MAKEINTRESOURCE(IDI_INFORMATION));
	wndcls.hInstance = hInstance;
	wndcls.lpfnWndProc = WinSunProc;
	wndcls.lpszClassName = "Sunxin2006";
	wndcls.lpszMenuName = NULL;
	wndcls.style = CS_HREDRAW | CS_VREDRAW;

	RegisterClass(&wndcls);

//	HWND hwnd;

	hwnd = CreateWindow("Sunxin2006","http:://www.sunxin.org",WS_OVERLAPPEDWINDOW,
		0,0,600,400,NULL,NULL,hInstance,NULL);

	ShowWindow(hwnd,SW_NORMAL);

	UpdateWindow(hwnd);

	MSG msg;

	while(GetMessage(&msg,NULL,0,0))
	{
		TranslateMessage(&msg);
		//DispatchMessage(&msg);
		if(msg.hwnd == hwnd && msg.message == WM_LBUTTONDOWN)
		{
			WMBUTTON();
		}
		else
		{
			DispatchMessage(&msg);
		}
	}

	return msg.wParam;
}

LRESULT CALLBACK WinSunProc(HWND hwnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	switch (uMsg)
	{
	case WM_CHAR:
		{			
			char szChar[20];

			sprintf(szChar,"char code is %d",wParam);
			MessageBox(hwnd,szChar,"char",MB_ICONINFORMATION);
			break;
		}
	/*
	case WM_LBUTTONDOWN:
		{					
			MessageBox(hwnd,"mouse clicked","message",MB_ICONINFORMATION);
			HDC hdc;
			hdc = GetDC(hwnd);
			TextOut(hdc,0,0,"http://www.sunxin.org",strlen("http://www.sunxin.org"));
			ReleaseDC(hwnd,hdc);
			break;
		}
		*/

	case WM_PAINT:
		{						
			HDC hdc;
			PAINTSTRUCT ps;
			hdc = BeginPaint(hwnd,&ps);
			TextOut(hdc,0,50,"程序员之家",strlen("程序员之家"));
			EndPaint(hwnd,&ps);
			break;
		}

	case WM_CLOSE:
		if(IDYES == MessageBox(hwnd,"是否真的结束","message",MB_YESNO | MB_ICONINFORMATION))
		{
			DestroyWindow(hwnd);
		}
		break;

	case WM_DESTROY:
		PostQuitMessage(0);
		break;

	default:
		return DefWindowProc(hwnd,uMsg,wParam,lParam);
	}

	return 0;
}

[jameshooo]

DispatchMessage比你想象的调用窗口过程复杂多了。
1、消息钩子链和消息过滤器需要处理。
2、纯线程消息（非窗口消息，无窗口过程）需要处理。
3、Send过来的系统内置消息的参数需要散列。
4、……

[Felix常温]

2楼的讲的不太明白，看来还有好多要学啊，多谢