public Data(SnapPoint snapPoint, IntPtr hWndChild, IntPtr hWndOwner, IntPtr hWndSnap)
{
this.snapPoint = snapPoint;
SnapHandle = hWndSnap;
nwChild = new ChildNW(hWndChild, this);
nwOwner = new OwnerNW(hWndOwner, this);
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == WM_SHOWWINDOW)
{
RECT rChild = new RECT();
RECT rOwner = new RECT();
GetWindowRect(data.SnapHandle, ref rOwner);
SnapPoint sp = data.snapPoint;
if (sp.NeedsChildRect)
{
GetWindowRect(Handle, ref rChild);
}
// must do this, otherwise when the window is invisible (e.g. owner is minimized) then its location resets
Point pt = sp.GetLocation(rChild, rOwner);
SetWindowPos(Handle, IntPtr.Zero, pt.X, pt.Y, 0, 0, SWP_NOOWNERZORDER | SWP_NOSIZE | SWP_NOZORDER | SWP_NOACTIVATE);
}
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
// several different approaches were tried, such as WM_MOVING, WM_MOVED, WM_WINDOWPOSCHANGING
// WM_MOVING and WM_MOVED do not account for resizing the window. WM_WINDOWPOSCHANGING fires
// false events (e.g. clicking on the title bar near (but not on) the minimize window button).
if (m.Msg == WM_WINDOWPOSCHANGED)
{
WINDOWPOS pos = (WINDOWPOS)Marshal.PtrToStructure(m.LParam, typeof(WINDOWPOS));
// -32000 means the window is minimized.
if (pos.x > -32000 && pos.y > -32000)
{
RECT rChild = new RECT();
RECT rOwner = new RECT();
if (data.SnapHandle == Handle)
{
rOwner.Top = pos.y;
rOwner.Left = pos.x;
rOwner.Bottom = pos.y + pos.cy;
rOwner.Right = pos.x + pos.cx;
}
else
{
GetWindowRect(data.SnapHandle, ref rOwner);
}
SnapPoint sp = data.snapPoint;
if (sp.NeedsChildRect)
{
GetWindowRect(data.nwChild.Handle, ref rChild);
}
Point pt = sp.GetLocation(rChild, rOwner);
SetWindowPos(data.nwChild.Handle, IntPtr.Zero, pt.X, pt.Y, 0, 0, SWP_NOOWNERZORDER | SWP_NOSIZE | SWP_NOZORDER | SWP_NOACTIVATE);
}
}
}
public static void SetOwner(IntPtr hWndChild, IntPtr hWndParent, IntPtr hWndTopLevel, SnapPoint snapPoint)
{
Data d = (Data)htData[hWndChild];
if (d != null)
{
d.nwOwner.ReleaseHandle();
if (hWndTopLevel != IntPtr.Zero)
{
d.nwOwner = new OwnerNW(hWndTopLevel, d);
}
else
{
d.nwChild.ReleaseHandle();
htData.Remove(hWndChild);
}
}
else
{
if (hWndTopLevel == IntPtr.Zero)
{
return;
}
d = new Data(snapPoint, hWndChild, hWndTopLevel, hWndParent);
htData[hWndChild] = d;
}
}
///<summary>Snaps the child window to the top level owner window, relative to the hWndSnap window. As
///the top level owner window is moved, resized, minimized or maximized, the child window moves too.</summary>
///<param name="child">The control that is automtically moved, e.g. a ToolStripDropDown window.</param>
///<param name="hWndTopLevel">A handle to a top-level window, e.g. a Form control's Handle.</param>
///<param name="hWndParent">A handle to a control that child window is relatively positioned, e.g. a TextBox or ComoBox.</param>
///<param name="snapPoint">Parameters that specify the X and Y location.</param>
public static void SnapWindow(this Control child, IntPtr hWndParent, IntPtr hWndTopLevel, SnapPoint snapPoint)
{
if (child.IsHandleCreated)
{
SetOwner(child.Handle, hWndParent, hWndTopLevel, snapPoint);
}
else
{
child.HandleCreated += delegate {
SetOwner(child.Handle, hWndParent, hWndTopLevel, snapPoint);
};
}
}