private void OnDpiChangedInteranl()
{
ScaleFactor = new DPI(CurrentDpi.X / WpfDpi.X, CurrentDpi.Y / WpfDpi.Y);
UpdateLayoutTransform(ScaleFactor);
OnDpiChanged();
}
/// <summary>
/// Uodate <see cref="Window.LayoutTransform"/> of the current <see cref="DpiAwareWindow"/>.
/// </summary>
/// <param name="scaleFactor"><see cref="DPI"/> representing scale factor.</param>
private void UpdateLayoutTransform(DPI scaleFactor)
{
if (IsPerMonitorEnabled == false)
{
return;
}
var child = GetVisualChild(0);
if ((scaleFactor.X != 1.0) || (scaleFactor.Y != 1.0))
{
child?.SetValue(LayoutTransformProperty, new ScaleTransform(scaleFactor.X, scaleFactor.Y));
}
else
{
child?.SetValue(LayoutTransformProperty, null);
}
}
/// <summary>
/// <see cref="FrameworkElement.Loaded"/> event handler.
/// </summary>
/// <param name="sender">event sender.</param>
/// <param name="args">event arguments.</param>
protected virtual void OnLoaded(object sender, RoutedEventArgs args)
{
// WPF has already scaled window size, graphics and text based on system DPI. In order to scale the window based on monitor DPI, update the
// window size, graphics and text based on monitor DPI. For example consider an application with size 600 x 400 in device independent pixels
// - Size in device independent pixels = 600 x 400
// - Size calculated by WPF based on system/WPF DPI = 192 (scale factor = 2)
// - Expected size based on monitor DPI = 144 (scale factor = 1.5)
// Similarly the graphics and text are updated updated by applying appropriate scale transform to the top level node of the WPF application
// Important Note: This method overwrites the size of the window and the scale transform of the root node of the WPF Window. Hence,
// this sample may not work "as is" if
// - The size of the window impacts other portions of the application like this WPF Window being hosted inside another application.
// - The WPF application that is extending this class is setting some other transform on the root visual; the sample may
// overwrite some other transform that is being applied by the WPF application itself.
SystemDpi = DpiHelper.GetSystemDpi();
var source = (HwndSource)PresentationSource.FromVisual(this);
source?.AddHook(WindowProcedureHook);
// Calculate the DPI used by WPF.
var transform = source?.CompositionTarget?.TransformToDevice;
WpfDpi = new DPI(96 * (transform?.M11 ?? 1), 96 * (transform?.M22 ?? 1));
if (IsPerMonitorEnabled && (source != null))
{
// Get the Current DPI of the monitor of the window.
CurrentDpi = DpiHelper.GetDpiForHwnd(source.Handle);
// Calculate the scale factor used to modify window size, graphics and text.
ScaleFactor = new DPI(CurrentDpi.X / WpfDpi.X, CurrentDpi.Y / WpfDpi.Y);
}
UpdateWindowSize();
UpdateLocation();
// Update graphics and text based on the current DPI of the monitor.
UpdateLayoutTransform(ScaleFactor);
OnDpiChanged();
}
/// <summary>
/// Message handler of the Per_Monitor_DPI_Aware window. The handles the WM_DPICHANGED message and adjusts window size, graphics and text
/// based on the DPI of the monitor. The window message provides the new window size (lparam) and new DPI (wparam)
/// </summary>
protected virtual IntPtr WindowProcedureHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
switch ((user32.WinMessages)msg)
{
case user32.WinMessages.WM_DPICHANGED:
if (IsPerMonitorEnabled)
{
user32.RECT newRect = (user32.RECT)Marshal.PtrToStructure(lParam, typeof(user32.RECT));
user32.SetWindowPos(hwnd, 0, newRect.Left, newRect.Top, newRect.Right - newRect.Left,
newRect.Bottom - newRect.Top,
user32.SWP_NOZORDER | user32.SWP_NOOWNERZORDER | user32.SWP_NOACTIVATE);
// Set the Window's position & size.
//Vector ul = source.CompositionTarget.TransformFromDevice.Transform(new Vector(newRect.Left, newRect.Top));
//Vector hw = source.CompositionTarget.TransformFromDevice.Transform(new Vector(newRect.Right = newRect.Left, newRect.Bottom - newRect.Top));
//Left = ul.X;
//Top = ul.Y;
//Width = hw.X;
//Height = hw.Y;
// Remember the current DPI settings.
var oldDpi = CurrentDpi;
// Get the new DPI settings from wParam
CurrentDpi = new DPI(wParam.ToInt32() >> 16, wParam.ToInt32() & 0x0000FFFF);
if ((oldDpi.X != CurrentDpi.X) || (oldDpi.Y != CurrentDpi.Y))
{
OnDpiChangedInteranl();
}
handled = true;
}
break;
}
return(IntPtr.Zero);
}
