/// <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();
}