/// <summary>
/// Message handler of the DPI Aware ContextMenuStrip, this is simplified compared to the normal
/// 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)
/// See
/// <a href="https://msdn.microsoft.com/en-us/library/windows/desktop/dn312083(v=vs.85).aspx">WM_DPICHANGED message</a>
/// </summary>
/// <param name="windowMessageInfo">WindowMessageInfo</param>
/// <returns>IntPtr</returns>
internal IntPtr HandleContextMenuMessages(WindowMessageInfo windowMessageInfo)
{
var currentDpi = DefaultScreenDpi;
bool isDpiMessage = false;
switch (windowMessageInfo.Message)
{
// Handle the WM_CREATE, this is where we can get the DPI via system calls
case WindowsMessages.WM_SHOWWINDOW:
isDpiMessage = true;
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Processing {0} event, retrieving DPI for ContextMenuStrip {1}", windowMessageInfo.Message, windowMessageInfo.Handle);
}
currentDpi = NativeDpiMethods.GetDpi(windowMessageInfo.Handle);
break;
case WindowsMessages.WM_DESTROY:
// If the window is destroyed, we complete the subject
_onDpiChanged.OnCompleted();
break;
}
// Check if the DPI was changed, if so call the action (if any)
if (!isDpiMessage)
{
return(IntPtr.Zero);
}
if (Dpi != currentDpi)
{
var beforeDpi = Dpi;
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("DPI changed from {0} to {1}", beforeDpi, currentDpi);
}
_onDpiChanged.OnNext(new DpiChangeInfo(beforeDpi, currentDpi));
Dpi = currentDpi;
}
else if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("DPI was unchanged from {0}", Dpi);
}
return(IntPtr.Zero);
}
/// <summary>
/// public wrapper for EnableNonClientDpiScaling, this also checks if the function is available.
/// </summary>
/// <param name="hWnd">IntPtr</param>
/// <returns>true if it worked</returns>
public static bool TryEnableNonClientDpiScaling(IntPtr hWnd)
{
// EnableNonClientDpiScaling is only available on Windows 10 and later
if (!WindowsVersion.IsWindows10OrLater)
{
return(false);
}
var result = NativeDpiMethods.EnableNonClientDpiScaling(hWnd);
if (result.Succeeded())
{
return(true);
}
var error = Win32.GetLastErrorCode();
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Error enabling non client dpi scaling : {0}", Win32.GetMessage(error));
}
return(false);
}
/// <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)
/// See
/// <a href="https://msdn.microsoft.com/en-us/library/windows/desktop/dn312083(v=vs.85).aspx">WM_DPICHANGED message</a>
/// </summary>
/// <param name="windowMessageInfo">WindowMessageInfo</param>
/// <returns>IntPtr</returns>
internal bool HandleWindowMessages(WindowMessageInfo windowMessageInfo)
{
bool handled = false;
var currentDpi = DefaultScreenDpi;
bool isDpiMessage = false;
switch (windowMessageInfo.Message)
{
// Handle the WM_NCCREATE for Forms / controls, for WPF this is done differently
case WindowsMessages.WM_NCCREATE:
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Processing {0} event, enabling DPI scaling for window {1}", windowMessageInfo.Message, windowMessageInfo.Handle);
}
TryEnableNonClientDpiScaling(windowMessageInfo.Handle);
break;
// Handle the WM_CREATE, this is where we can get the DPI via system calls
case WindowsMessages.WM_CREATE:
isDpiMessage = true;
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Processing {0} event, retrieving DPI for window {1}", windowMessageInfo.Message, windowMessageInfo.Handle);
}
currentDpi = NativeDpiMethods.GetDpi(windowMessageInfo.Handle);
_scopedThreadDpiAwarenessContext.Dispose();
break;
// Handle the DPI change message, this is where it's supplied
case WindowsMessages.WM_DPICHANGED:
isDpiMessage = true;
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Processing {0} event, resizing / positioning window {1}", windowMessageInfo.Message, windowMessageInfo.Handle);
}
// Retrieve the adviced location
var lprNewRect = (NativeRect)Marshal.PtrToStructure(windowMessageInfo.LongParam, typeof(NativeRect));
// Move the window to it's location, and resize
User32Api.SetWindowPos(windowMessageInfo.Handle,
IntPtr.Zero,
lprNewRect.Left,
lprNewRect.Top,
lprNewRect.Width,
lprNewRect.Height,
WindowPos.SWP_NOZORDER | WindowPos.SWP_NOOWNERZORDER | WindowPos.SWP_NOACTIVATE);
currentDpi = (uint)windowMessageInfo.WordParam & 0xFFFF;
// specify that the message was handled
handled = true;
break;
case WindowsMessages.WM_PAINT:
// This is a workaround for non DPI aware applications, these don't seem to get a WM_CREATE
if (Dpi == 0)
{
isDpiMessage = true;
currentDpi = NativeDpiMethods.GetDpi(windowMessageInfo.Handle);
}
break;
case WindowsMessages.WM_SETICON:
// This is a workaround for handling WinProc outside of the class
if (_needsListenerWorkaround)
{
isDpiMessage = true;
// disable workaround
_needsListenerWorkaround = false;
currentDpi = NativeDpiMethods.GetDpi(windowMessageInfo.Handle);
}
break;
case WindowsMessages.WM_DPICHANGED_BEFOREPARENT:
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Dpi changed on {0} before parent", windowMessageInfo.Handle);
}
break;
case WindowsMessages.WM_DPICHANGED_AFTERPARENT:
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Dpi changed on {0} after parent", windowMessageInfo.Handle);
}
break;
case WindowsMessages.WM_DESTROY:
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Completing the observable for {0}", windowMessageInfo.Handle);
}
// If the window is destroyed, we complete the subject
_onDpiChanged.OnCompleted();
// Dispose all resources
Dispose();
break;
}
// Check if the DPI was changed, if so call the action (if any)
if (!isDpiMessage)
{
return(false);
}
if (Dpi != currentDpi)
{
var beforeDpi = Dpi;
if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("Changing DPI from {0} to {1}", beforeDpi, currentDpi);
}
Dpi = currentDpi;
_onDpiChanged.OnNext(new DpiChangeInfo(beforeDpi, currentDpi));
}
else if (Log.IsVerboseEnabled())
{
Log.Verbose().WriteLine("DPI was unchanged from {0}", Dpi);
}
return(handled);
}
/// <summary>
/// Create a DpiHandler
/// </summary>
public DpiHandler(bool needsListenerWorkaround = false)
{
_needsListenerWorkaround = needsListenerWorkaround;
_scopedThreadDpiAwarenessContext = NativeDpiMethods.DefaultScopedThreadDpiAwarenessContext();
}
