Using Cursor Functions to Create a Mousetrap

The following example uses the SetCursorPos, GetCursorPos, CreateCursor, LoadCursor, and SetCursor functions to create a simple mousetrap. It also uses cursor and timer functions to monitor the cursor's position every 10 seconds. If the cursor position has not changed in the last 10 seconds and the application's main window is minimized, the application changes the cursor and moves it to the mousetrap icon.

An example for a similar mousetrap is included in Icons. It uses the LoadCursor and LoadIcon functions instead of the more device-dependent CreateCursor and CreateIcon functions.

HICON hIcon1;               // icon handles 
POINT ptOld;                // previous cursor location 
HCURSOR hCurs1;             // cursor handle 
 
 
// The following cursor bitmasks are defined in a code 
// example that appears earlier in this topic. 
 
// Yin cursor AND and XOR bitmasks 
 
BYTE ANDmaskCursor[] = ... 
BYTE XORmaskCursor[] = ... 
 
// Yang icon AND bitmask 
 
BYTE ANDmaskIcon[] = {0xFF, 0xFF, 0xFF, 0xFF,  // line 1 
                      0xFF, 0xFF, 0xC3, 0xFF,  // line 2 
                      0xFF, 0xFF, 0x00, 0xFF,  // line 3 
                      0xFF, 0xFE, 0x00, 0x7F,  // line 4 
 
                      0xFF, 0xFC, 0x00, 0x1F,  // line 5 
                      0xFF, 0xF8, 0x00, 0x0F,  // line 6 
                      0xFF, 0xF8, 0x00, 0x0F,  // line 7 
                      0xFF, 0xF0, 0x00, 0x07,  // line 8 
 
                      0xFF, 0xF0, 0x00, 0x03,  // line 9 
                      0xFF, 0xE0, 0x00, 0x03,  // line 10 
                      0xFF, 0xE0, 0x00, 0x01,  // line 11 
                      0xFF, 0xE0, 0x00, 0x01,  // line 12 
 
                      0xFF, 0xF0, 0x00, 0x01,  // line 13 
                      0xFF, 0xF0, 0x00, 0x00,  // line 14 
                      0xFF, 0xF8, 0x00, 0x00,  // line 15 
                      0xFF, 0xFC, 0x00, 0x00,  // line 16 
 
                      0xFF, 0xFF, 0x00, 0x00,  // line 17 
                      0xFF, 0xFF, 0x80, 0x00,  // line 18 
                      0xFF, 0xFF, 0xE0, 0x00,  // line 19 
                      0xFF, 0xFF, 0xE0, 0x01,  // line 20 
 
                      0xFF, 0xFF, 0xF0, 0x01,  // line 21 
                      0xFF, 0xFF, 0xF0, 0x01,  // line 22 
                      0xFF, 0xFF, 0xF0, 0x03,  // line 23 
                      0xFF, 0xFF, 0xE0, 0x03,  // line 24 
 
                      0xFF, 0xFF, 0xE0, 0x07,  // line 25 
                      0xFF, 0xFF, 0xC0, 0x0F,  // line 26 
                      0xFF, 0xFF, 0xC0, 0x0F,  // line 27 
                      0xFF, 0xFF, 0x80, 0x1F,  // line 28 
 
                      0xFF, 0xFF, 0x00, 0x7F,  // line 29 
                      0xFF, 0xFC, 0x00, 0xFF,  // line 30 
                      0xFF, 0xF8, 0x03, 0xFF,  // line 31 
                      0xFF, 0xFC, 0x3F, 0xFF}; // line 32 
 
// Yang icon XOR bitmask 
 
BYTE XORmaskIcon[] = {0x00, 0x00, 0x00, 0x00,  // line 1 
                      0x00, 0x00, 0x00, 0x00,  // line 2 
                      0x00, 0x00, 0x00, 0x00,  // line 3 
                      0x00, 0x00, 0x00, 0x00,  // line 4 
 
                      0x00, 0x00, 0x00, 0x00,  // line 5 
                      0x00, 0x00, 0x00, 0x00,  // line 6 
                      0x00, 0x00, 0x00, 0x00,  // line 7 
                      0x00, 0x00, 0x38, 0x00,  // line 8 
 
                      0x00, 0x00, 0x7C, 0x00,  // line 9 
                      0x00, 0x00, 0x7C, 0x00,  // line 10 
                      0x00, 0x00, 0x7C, 0x00,  // line 11  
                      0x00, 0x00, 0x38, 0x00,  // line 12 
 
                      0x00, 0x00, 0x00, 0x00,  // line 13 
                      0x00, 0x00, 0x00, 0x00,  // line 14 
                      0x00, 0x00, 0x00, 0x00,  // line 15 
                      0x00, 0x00, 0x00, 0x00,  // line 16 
 
                      0x00, 0x00, 0x00, 0x00,  // line 17 
                      0x00, 0x00, 0x00, 0x00,  // line 18 
                      0x00, 0x00, 0x00, 0x00,  // line 19 
                      0x00, 0x00, 0x00, 0x00,  // line 20 
 
                      0x00, 0x00, 0x00, 0x00,  // line 21 
                      0x00, 0x00, 0x00, 0x00,  // line 22 
                      0x00, 0x00, 0x00, 0x00,  // line 23 
                      0x00, 0x00, 0x00, 0x00,  // line 24 
 
                      0x00, 0x00, 0x00, 0x00,  // line 25 
                      0x00, 0x00, 0x00, 0x00,  // line 26 
                      0x00, 0x00, 0x00, 0x00,  // line 27 
                      0x00, 0x00, 0x00, 0x00,  // line 28 
 
                      0x00, 0x00, 0x00, 0x00,  // line 29 
                      0x00, 0x00, 0x00, 0x00,  // line 30 
                      0x00, 0x00, 0x00, 0x00,  // line 31 
                      0x00, 0x00, 0x00, 0x00}; // line 32 
 
hIcon1 = CreateIcon(hinst, // handle to app instance 
             32,           // icon width 
             32,           // icon height 
             1,            // number of XOR planes 
             1,            // number of bits per pixel 
             ANDmaskIcon,  // AND bitmask 
             XORmaskIcon); // XOR bitmask 
 
hCurs1 = CreateCursor(hinst, // handle to app instance
             19,         // horizontal position of hot spot 
             2,          // vertical position of hot spot 
             32,         // cursor width 
             32,         // cursor height 
             ANDmaskCursor,            // AND bitmask 
             XORmaskCursor);           // XOR bitmask 
 
// Fill in the window class structure. 
 
WNDCLASS  wc; 
 
wc.hIcon = hIcon1;                        // class icon 
wc.hCursor = LoadCursor(NULL, IDC_ARROW); // class cursor 
 
//
// Register the window class and perform 
// other application initialization. 
//
 
// Set a timer for the mousetrap. 
 
GetCursorPos(&ptOld); 
 
SetTimer(hwnd, IDT_CURSOR, 10000, (TIMERPROC) NULL); 
 
LONG APIENTRY MainWndProc( 
    HWND hwnd,          // window handle 
    UINT message,       // type of message 
    UINT wParam,        // additional information 
    LONG lParam)        // additional information 
{ 
 
    HDC hdc;            // handle to device context 
    POINT pt;           // current cursor location 
    RECT rc;            // iconized window location 
 
    switch (message) 
    { 
        //
        // Process other messages. 
        // 

        case WM_TIMER: 
        // If the window is minimized, compare the 
        // current cursor position with the one 10 
        // seconds before. If the cursor position has 
        // not changed, move the cursor to the icon. 
 
            if (IsIconic(hwnd)) 
            { 
                GetCursorPos(&pt); 
 
                if ((pt.x == ptOld.x) && (pt.y == ptOld.y)) 
                { 
                    GetWindowRect(hwnd, &rc); 
                    SetCursorPos(rc.left + 20, rc.top + 4); 
 
                    // Note that the additional constants 
                    // (20 and 4) are application-specific 
                    // values to align the yin-shaped cursor 
                    // and the yang-shaped icon. 
 
                } 
                else 
                { 
                    ptOld.x = pt.x; 
                    ptOld.y = pt.y; 
                } 
            } 
 
            return 0; 
 
        case WM_SETCURSOR: 
        // If the window is minimized, draw hCurs1. 
        // If the window is not minimized, draw the 
        // default cursor (class cursor). 
 
            if (IsIconic(hwnd)) 
            { 
                SetCursor(hCurs1); 
                break; 
            } 
 
        case WM_DESTROY: 
        // Destroy timer. 
 
            KillTimer(hwnd, IDT_CURSOR); 
 
            PostQuitMessage(0); 
            break; 
    } 
}