program RandRect;
//程序5-7 RandRect
uses
Windows, Messages;
var
cxClient, cyClient: LongWord;
procedure DrawRectangle(hWindow: HWND);
var
hWndc: HDC;
hBrush1: HBRUSH;
rc: TRect;
begin
if (0=cxClient) or (0=cyClient) then
exit;
SetRect(rc, random(cxClient), random(cyClient), random(cxClient), random(cyClient));
hBrush1:= CreateSolidBrush(RGB(random(256), random(256), random(256)));
hWndc:= GetDC(hWindow);
FillRect(hWndc, rc, hBrush1);
ReleaseDC(hWindow, hWndc);
DeleteObject(hBrush1);
end;
function WndProc(hWindow: HWND; Msg, wParam, lParam: LongInt): LRESULT; stdcall;
var
ps: TPaintStruct;
hWndc: HDC;
begin
Result:= 0;
case Msg of
WM_CREATE:
begin
end;
WM_PAINT:
begin //只要自己处理重绘消息，以下两句必须有， 否则有问题。
hWndc:= BeginPaint(hWindow, ps);
EndPaint(hWindow, ps);
end;
WM_SIZE:
begin
cxClient:= LoWord(lParam);
cyClient:= HiWord(lParam);
end;
WM_DESTROY:
begin
PostQuitMessage(0);
end
else
Result:= DefWindowProc(hWindow, Msg, wParam, lParam);
end;
end;
const
szAppName = 'RandRect';
var
wndclass1: TWndClass;
Msg: TMsg;
hWindow: HWND;
begin
wndclass1.style:= CS_VREDRAW or CS_HREDRAW;
wndclass1.lpfnWndProc:= @WndProc;
wndclass1.cbClsExtra:= 0;
wndclass1.cbWndExtra:= 0;
wndclass1.hInstance:= HInstance;
wndclass1.hIcon:= LoadIcon(0, 0);
wndclass1.hCursor:= LoadCursor(0, 0);
wndclass1.hbrBackground:= GetStockObject(0);
wndclass1.lpszMenuName:= nil;
wndclass1.lpszClassName:= szAppName;
if RegisterClass(wndclass1) = 0 then
begin
MessageBox(0, 'This program requires windows NT!', szAppName, MB_ICONERROR);
exit;
end;
hWindow:= CreateWindow(szAppname, 'Random Rectangles', WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, 0, 0, HInstance, nil);
ShowWindow(hWindow, CmdShow);
UpdateWindow(hWindow);
while True do
begin
if PeekMessage(Msg, 0, 0, 0, PM_REMOVE) then
begin
if Msg.message = WM_QUIT then
break;
TranslateMessage(Msg);
DispatchMessage(Msg);
end
else
begin
DrawRectangle(hWindow);
Sleep(10);
end;
end;
end.
