The source code is as follows:
#include <windows.h>
#define MAXPOINTS 1000
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);
RECT rect;
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("Connect");
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 Window NT!"), szAppName, MB_ICONERROR);
return 0;
}
hwnd = CreateWindow (szAppName, TEXT("Connect-the-Points Mouse 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 POINT pt[MAXPOINTS];
static int iCount;
HDC hdc;
int i, j;
PAINTSTRUCT ps;
switch (message)
{
case WM_LBUTTONDOWN:
iCount = 0;
InvalidateRect(hwnd, NULL, TRUE);
return 0;
case WM_MOUSEMOVE:
if(wParam & MK_LBUTTON && iCount < 1000)
{
pt[iCount].x = LOWORD(lParam);
pt[iCount++].y = HIWORD(lParam);
hdc = GetDC(hwnd);
SetPixel(hdc, LOWORD(lParam), HIWORD(lParam), 0);
ReleaseDC(hwnd, hdc);
}
return 0;
case WM_LBUTTONUP:
InvalidateRect(hwnd, NULL, FALSE);
return 0;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
SetCursor(LoadCursor(NULL, IDC_WAIT));
ShowCursor(TRUE);
for(i = 0; i < iCount - 1; i++)
for(j = i + 1; j < iCount; j++)
{
MoveToEx(hdc, pt[i].x, pt[i].y, NULL);
LineTo(hdc, pt[j].x, pt[j].y);
}
ShowCursor(FALSE);
SetCursor(LoadCursor(NULL, IDC_ARROW));
EndPaint(hwnd, &ps);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc (hwnd, message, wParam, lParam);
}The results are shown in the figure:
Move the mouse pointer to the client area, press the left button, move the mouse slightly, and then release the left button. Press the left button and move the mouse quickly to get a curve that passes through multiple points.
