新手问：WM_PAINT和WM_SIZE的先后顺序问题？
我想知道在下面的代码中WM_PAINT和WM_SIZE的顺序。
/*--------------------------------------------------
CLOVER.C -- Clover Drawing Program Using Regions
(c) Charles Petzold, 1998
--------------------------------------------------*/
#include <windows.h>
#include <math.h>
#define TWO_PI (2.0 * 3.14159)
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ( "Clover ") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;
if (!RegisterClass (&wndclass))
{
MessageBox (NULL, TEXT ( "This program requires Windows NT! "),
szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow (szAppName, TEXT ( "Draw a Clover "),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL) ;
ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;
while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
static HRGN hRgnClip ;
static int cxClient, cyClient ;
double fAngle, fRadius ;
HCURSOR hCursor ;
HDC hdc ;
HRGN hRgnTemp[6] ;
int i ;
PAINTSTRUCT ps ;
switch (iMsg)
{
case WM_SIZE:
cxClient = LOWORD (lParam) ;
cyClient = HIWORD (lParam) ;
MessageBox ( hwnd,TEXT( "this is in WM_SIZE before !! ") ,TEXT( " in size before "),NULL );
hCursor = SetCursor (LoadCursor (NULL, IDC_WAIT)) ;
ShowCursor (TRUE) ;
// MessageBox ( hwnd,TEXT( "this is in WM_SIZE !! ") ,TEXT( " in size "),NULL );
if (hRgnClip)
DeleteObject (hRgnClip) ;
// MessageBox ( hwnd,TEXT( "this is in WM_SIZE brfore !! ") ,TEXT( " in size "),NULL );
hRgnTemp[0] = CreateEllipticRgn (0, cyClient / 3,
cxClient / 2, 2 * cyClient / 3) ;
hRgnTemp[1] = CreateEllipticRgn (cxClient / 2, cyClient / 3,
cxClient, 2 * cyClient / 3) ;
hRgnTemp[2] = CreateEllipticRgn (cxClient / 3, 0,
2 * cxClient / 3, cyClient / 2) ;
hRgnTemp[3] = CreateEllipticRgn (cxClient / 3, cyClient / 2,
2 * cxClient / 3, cyClient) ;
hRgnTemp[4] = CreateRectRgn (0, 0, 1, 1) ;
hRgnTemp[5] = CreateRectRgn (0, 0, 1, 1) ;
hRgnClip = CreateRectRgn (0, 0, 1, 1) ;
CombineRgn (hRgnTemp[4], hRgnTemp[0], hRgnTemp[1], RGN_OR) ;
CombineRgn (hRgnTemp[5], hRgnTemp[2], hRgnTemp[3], RGN_OR) ;
CombineRgn (hRgnClip, hRgnTemp[4], hRgnTemp[5], RGN_XOR) ;
//MessageBox ( hwnd,TEXT( "this is in WM_SIZE after!! ") ,TEXT( " in size after "),NULL );
for (i = 0 ; i < 6 ; i++)
DeleteObject (hRgnTemp[i]) ;
SetCursor (hCursor) ;
ShowCursor (FALSE) ;
return 0 ;
case WM_PAINT:
hdc = BeginPaint (hwnd, &ps) ;
MessageBox ( hwnd,TEXT( "this is in WM_PAINT before !! ") ,TEXT( " in paint before "),NULL );
SetViewportOrgEx (hdc, cxClient / 2, cyClient / 2, NULL) ;
SelectClipRgn (hdc, hRgnClip) ;
fRadius = _hypot (cxClient / 2.0, cyClient / 2.0) ;
for (fAngle = 0.0 ; fAngle < TWO_PI ; fAngle += TWO_PI / 360)
{
MoveToEx (hdc, 0, 0, NULL) ;
LineTo (hdc, (int) ( fRadius * cos (fAngle) + 0.5),
(int) (-fRadius * sin (fAngle) + 0.5)) ;
}
// MessageBox ( hwnd,TEXT( "this is in WM_PAINT after!! ") ,TEXT( " in paint after "),NULL );
EndPaint (hwnd, &ps) ;
return 0 ;
case WM_DESTROY:
DeleteObject (hRgnClip) ;
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
}
我通过加MessageBox得到WM_PAINT然后WM_SIZE但是在CSDN以前的贴子中说的刚好相反，贴子为：http://topic.csdn.net/t/20030223/12/1456618.html#
高人能给个解释吗？尤其是在windows 是消息这一部分。。
[解决办法]
这样说吧，比如你改变窗体大小，那么就是WM_SIZE
当窗体最小化又还原的时候就是WM_PAINT。
但是我怎么知道楼主你是先改变它大小还是先吧它最小化。我又不是你。
[解决办法]
窗口在初次显示的时候是先有WM_SIZE，然后才是WM_PAINT。另外，一般不要在WM_PAINT中调用MessageBox，这可能会导致窗口不断的重绘，你可以使用OutputDebugString，或者其它不会影响UI的方法
[解决办法]
当窗口从无到有的时候,整个客户区都是无效的,这是会产生WM_PAINT消息;
当调用ShowWindow函数时,此函数会发送WM_SIZE消息;
以后如果窗口的客户区在产生无效区域,那么就会发送WM_PAINT消息,
如果窗口大小发生变化,会发送WM_SIZE消息
