Windows程式内部運作原理的一個示例
一、原理
http://blog.163.com/zhoumhan_0351/blog/static/3995422720103401415721
二、例程
#include "windows.h"
#include "stdio.h"
LRESULT CALLBACK WinWeProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);
int WINAPI WinMain(
HINSTANCE hInstance, // handle to current instance
HINSTANCE hPrevInstance, // handle to previous instance
LPSTR lpCmdLine, // command line
int nCmdShow // show state
)
{
WNDCLASS wndcls;
wndcls.cbClsExtra=0;
wndcls.cbWndExtra=0;
wndcls.hbrBackground=(HBRUSH)GetStockObject(BLACK_BRUSH);
wndcls.hCursor=LoadCursor(NULL,IDC_CROSS);
wndcls.hIcon=LoadIcon(NULL,IDI_ASTERISK);
wndcls.hInstance=hInstance;
wndcls.lpfnWndProc=WinWeProc;
wndcls.lpszClassName="WinWe2010";
wndcls.lpszMenuName=NULL;
wndcls.style=CS_HREDRAW | CS_VREDRAW;
RegisterClass(&wndcls);
HWND hwnd;
hwnd=CreateWindow("WinWe2010","I am Here",WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,600,400,NULL,NULL,
hInstance,NULL);
ShowWindow(hwnd,SW_SHOWNORMAL);
UpdateWindow(hwnd);
MSG msg;
while(GetMessage(&msg,NULL,0,0)){
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WinWeProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
)
{
switch(uMsg)
{
case WM_CHAR:
char szChar[20];
sprintf(szChar,"char code is %d",wParam);
MessageBox(hwnd,szChar,"char",0);
break;
case WM_LBUTTONDOWN:
MessageBox(hwnd,"mouse","message",0);
HDC hdc;
hdc=GetDC(hwnd);
TextOut(hdc,0,50,"MY home",strlen("MY home"));
ReleaseDC(hwnd,hdc);
break;
case WM_PAINT:
HDC hDc;
PAINTSTRUCT ps;
hDc=BeginPaint(hwnd,&ps);
TextOut(hDc,0,0,"HELLO",strlen("HELLO"));
EndPaint(hwnd,&ps);
break;
case WM_CLOSE:
if(IDYES==MessageBox(hwnd,"Really?","message",MB_YESNO)){
DestroyWindow(hwnd);
}
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd,uMsg,wParam,lParam);
}
return 0;
}
三、注意點
1、wndcls.hbrBackground=(HBRUSH)GetStockObject(BLACK_BRUSH);
2、char szChar[20];
sprintf(szChar,"char code is %d",wParam);
MessageBox(hwnd,szChar,"char",0);
3、hdc=GetDC(hwnd);
TextOut(hdc,0,50,"MY home",strlen("MY home"));
ReleaseDC(hwnd,hdc);
//記得GetDC後要ReleaseDC,否則可能記憶體洩露。在Windows平台下,所有的圖形操作操作都是選用DC的,可以把DC想成畫布,我們不是作畫者,而是指揮者,指揮DC畫什麼圖形。實際上,DC是一個包含裝置(實體裝置,如輸出裝置,顯示器,及裝置驅動程式等)資訊的結構體。DC也是一種資源。
4、hDc=BeginPaint(hwnd,&ps);
TextOut(hDc,0,0,"HELLO",strlen("HELLO"));
EndPaint(hwnd,&ps);
//BeginPaint後要EndPaint,他們是一對,隻能用在WM_PAINT消息響應代碼中使用。
5、調用UpdateWindow時,會發送WM_PAINT消息給視窗函數,對視窗函數進行重新整理。
6、邏輯表達式中,當是判斷相等時,如果有常量,應當把常量放前面,友善調試和糾錯,如下所示:
if(IDYES==MessageBox(hwnd,"Really?","message",MB_YESNO))
7、變量的命名約定