rr的求问关于api里面的那个PAINTSTRUCT结构

[jellodgd]

最近刚在看Petzold的那本windows程序设计，一直不知道里面的那个ps有什么用。ps里不是定义了无效矩形rePaint嘛，怎么看了书上的许多例子，都用不到这个无效矩形呢？

象一个例子里的（7-2 CHECKER1程序，书上p265）

/*-------------------------------------------------
CHECKER1.C -- Mouse Hit-Test Demo Program No. 1
(c) Charles Petzold, 1998
-------------------------------------------------*/

#include <windows.h>

#define DIVISIONS 5

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("Checker1") ;
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 ("Program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}

hwnd = CreateWindow (szAppName, TEXT ("Checker1 Mouse Hit-Test Demo"),
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 message, WPARAM wParam, LPARAM lParam)
{
static BOOL fState[DIVISIONS][DIVISIONS] ;
static int cxBlock, cyBlock ;
HDC hdc ;
int x, y ;
PAINTSTRUCT ps ;
RECT rect ;

switch (message)
{
case WM_SIZE :
cxBlock = LOWORD (lParam) / DIVISIONS ;
cyBlock = HIWORD (lParam) / DIVISIONS ;
return 0 ;

case WM_LBUTTONDOWN :
x = LOWORD (lParam) / cxBlock ;
y = HIWORD (lParam) / cyBlock ;

if (x < DIVISIONS && y < DIVISIONS)
{
fState [x][y] ^= 1 ;

rect.left = x * cxBlock ;
rect.top = y * cyBlock ;
rect.right = (x + 1) * cxBlock ;
rect.bottom = (y + 1) * cyBlock ;

InvalidateRect (hwnd, &rect, FALSE) ;
}
else
MessageBeep (0) ;
return 0 ;

case WM_PAINT :
hdc = BeginPaint (hwnd, &ps) ;

for (x = 0 ; x < DIVISIONS ; x++)
for (y = 0 ; y < DIVISIONS ; y++)
{
Rectangle (hdc, x * cxBlock, y * cyBlock,
(x + 1) * cxBlock, (y + 1) * cyBlock) ;

if (fState [x][y])
{
MoveToEx (hdc, x * cxBlock, y * cyBlock, NULL) ;
LineTo (hdc, (x+1) * cxBlock, (y+1) * cyBlock) ;
MoveToEx (hdc, x * cxBlock, (y+1) * cyBlock, NULL) ;
LineTo (hdc, (x+1) * cxBlock, y * cyBlock) ;
}
}
EndPaint (hwnd, &ps) ;
return 0 ;

case WM_DESTROY :
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}




InvalidateRect (hwnd, &rect, FALSE) ;不是只使一个rect所表示的矩形实效嘛，那收到WM_PAINT消息后，ps的结构里的rePaint是不是就==这里的rect？但好象处理WM_PAINT的时候并没有用到这个结构呀？搞死了这两天= =

[danielzhu]

hdc = BeginPaint (hwnd, &ps) ;
EndPaint (hwnd, &ps) ;
这两个地方都用到了

[jellodgd]

对啊
但只是填充一下和释放一下吧？
好象也么看到有什么用嘛？
T_T