Positionieren von Objekten in einem Setup mit mehreren Bildschirmen

Der folgende Beispielcode veranschaulicht, wie Anwendungen Objekte auf mehreren Displays richtig positionieren können. Beachten Sie, dass das RECT nicht auf dem Ursprung (0,0) basiert.

#include <windows.h>
#include "multimon.h"    

#define MONITOR_CENTER     0x0001        // center rect to monitor 
#define MONITOR_CLIP     0x0000        // clip rect to monitor 
#define MONITOR_WORKAREA 0x0002        // use monitor work area 
#define MONITOR_AREA     0x0000        // use monitor entire area 

// 
//  ClipOrCenterRectToMonitor 
// 
//  The most common problem apps have when running on a 
//  multimonitor system is that they "clip" or "pin" windows 
//  based on the SM_CXSCREEN and SM_CYSCREEN system metrics. 
//  Because of app compatibility reasons these system metrics 
//  return the size of the primary monitor. 
// 
//  This shows how you use the multi-monitor functions 
//  to do the same thing. 
// 
void ClipOrCenterRectToMonitor(LPRECT prc, UINT flags)
{
    HMONITOR hMonitor;
    MONITORINFO mi;
    RECT        rc;
    int         w = prc->right  - prc->left;
    int         h = prc->bottom - prc->top;

    // 
    // get the nearest monitor to the passed rect. 
    // 
    hMonitor = MonitorFromRect(prc, MONITOR_DEFAULTTONEAREST);

    // 
    // get the work area or entire monitor rect. 
    // 
    mi.cbSize = sizeof(mi);
    GetMonitorInfo(hMonitor, &mi);

    if (flags & MONITOR_WORKAREA)
        rc = mi.rcWork;
    else
        rc = mi.rcMonitor;

    // 
    // center or clip the passed rect to the monitor rect 
    // 
    if (flags & MONITOR_CENTER)
    {
        prc->left   = rc.left + (rc.right  - rc.left - w) / 2;
        prc->top    = rc.top  + (rc.bottom - rc.top  - h) / 2;
        prc->right  = prc->left + w;
        prc->bottom = prc->top  + h;
    }
    else
    {
        prc->left   = max(rc.left, min(rc.right-w,  prc->left));
        prc->top    = max(rc.top,  min(rc.bottom-h, prc->top));
        prc->right  = prc->left + w;
        prc->bottom = prc->top  + h;
    }
}

void ClipOrCenterWindowToMonitor(HWND hwnd, UINT flags)
{
    RECT rc;
    GetWindowRect(hwnd, &rc);
    ClipOrCenterRectToMonitor(&rc, flags);
    SetWindowPos(hwnd, NULL, rc.left, rc.top, 0, 0, SWP_NOSIZE | SWP_NOZORDER | SWP_NOACTIVATE);
}