protected IntPtr HandleNCHitTest(IntPtr lParam)
{
// Because we still have the System Border (which technically extends beyond the actual window
// into where the Drop shadows are), we can use DefWindowProc here to handle resizing, except
// on the top. We'll handle that below
var originalRet = Win32Interop.DefWindowProc(Hwnd, (uint)WM.NCHITTEST, IntPtr.Zero, lParam);
if (originalRet != new IntPtr(1))
{
return(originalRet);
}
// At this point, we know that the cursor is inside the client area so it
// has to be either the little border at the top of our custom title bar,
// the drag bar or something else in the XAML island. But the XAML Island
// handles WM_NCHITTEST on its own so actually it cannot be the XAML
// Island. Then it must be the drag bar or the little border at the top
// which the user can use to move or resize the window.
var point = PointToClient(PointFromLParam(lParam));
RECT rcWindow;
Win32Interop.GetWindowRect(Hwnd, out rcWindow);
// On the Top border, the resize handle overlaps with the Titlebar area, which matches
// a typical Win32 window or modern app window
var resizeBorderHeight = GetResizeHandleHeight();
bool isOnResizeBorder = point.Y < resizeBorderHeight;
// Make sure the caption buttons still get precedence
// This is where things get tricky too. On Win11, we still want to suppor the snap
// layout feature when hovering over the Maximize button. Unfortunately no API exists
// yet to call that manually if using a custom titlebar. But, if we return HT_MAXBUTTON
// here, the pointer events no longer enter the window
// See https://github.com/dotnet/wpf/issues/4825 for more on this...
// To hack our way into making this work, we'll return HT_MAXBUTTON here, but manually
// manage the state and handle stuff through the WM_NCLBUTTON... events
// This only applies on Windows 11, Windows 10 will work normally b/c no snap layout thing
if (_owner !.HitTestCaptionButtons(point))
{
if (_isWindows11)
{
var result = _owner.HitTestMaximizeButton(point);
if (result)
{
_fakingMaximizeButton = true;
return(new IntPtr(9));
}
}
}
protected override IntPtr WndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
{
switch ((WM)msg)
{
case WM.NCCALCSIZE:
// Follows logic from how to extend window frame + WindowsTerminal + Firefox
// Windows Terminal only handles WPARAM = TRUE & only adjusts the top of the
// rgrc[0] RECT & gets the correct result
// Firefox, on the other hand, handles BOTH times WM_NCCALCSIZE is called,
// and modifies the RECT.
// This particularly differs from the "built-in" method in Avalonia in that
// I retain the SystemBorder & ability resize the window in the transparent
// area over the drop shadows, meaning resize handles don't overlap the window
if (wParam != IntPtr.Zero &&
_owner?.Window.CanResize == true)
{
var ncParams = Marshal.PtrToStructure <NCCALCSIZE_PARAMS>(lParam);
var originalTop = ncParams.rgrc[0].top;
var ret = Win32Interop.DefWindowProc(hWnd, (uint)WM.NCCALCSIZE, wParam, lParam);
if (ret != IntPtr.Zero)
{
return(ret);
}
var newSize = ncParams.rgrc[0];
if (newSize.Width == ncParams.rgrc[1].Width &&
newSize.Height == ncParams.rgrc[1].Height)
{
Marshal.StructureToPtr(ncParams, lParam, true);
return(IntPtr.Zero);
}
newSize.top = originalTop;
if (WindowState == WindowState.Maximized ||
WindowState == WindowState.FullScreen)
{
//newSize.top += GetResizeHandleHeight();
}
else
{
if (_owner != null)
{
newSize.left += 8;
newSize.right -= 8;
newSize.bottom -= 8;
}
}
ncParams.rgrc[0] = newSize;
Marshal.StructureToPtr(ncParams, lParam, true);
return(IntPtr.Zero);
}
break;
//case WM.NCHITTEST:
// return HandleNCHitTest(lParam);
case WM.SIZE:
EnsureExtended();
if (_fakingMaximizeButton)
{
// Sometimes the effect can get stuck, so if we resize, clear it
_owner.FakeMaximizePressed(false);
_wasFakeMaximizeDown = false;
}
break;
case WM.ACTIVATE:
EnsureExtended();
break;
case WM.NCMOUSEMOVE:
if (_fakingMaximizeButton)
{
var point = PointToClient(PointFromLParam(lParam));
_owner.FakeMaximizeHover(_owner.HitTestMaximizeButton(point));
return(IntPtr.Zero);
}
break;
case WM.NCLBUTTONDOWN:
if (_fakingMaximizeButton)
{
var point = PointToClient(PointFromLParam(lParam));
_owner.FakeMaximizePressed(_owner.HitTestMaximizeButton(point));
_wasFakeMaximizeDown = true;
// This is important. If we don't tell the System we've handled this, we'll get that
// classic Win32 button showing when we mouse press, and that's not good
return(IntPtr.Zero);
}
break;
case WM.NCLBUTTONUP:
if (_fakingMaximizeButton && _wasFakeMaximizeDown)
{
var point = PointToClient(PointFromLParam(lParam));
_owner.FakeMaximizePressed(false);
_wasFakeMaximizeDown = false;
_owner.FakeMaximizeClick();
return(IntPtr.Zero);
}
break;
}
return(base.WndProc(hWnd, msg, wParam, lParam));
}