/// <summary>
/// Gets the specified window attribute from the Desktop Window Manager (DWM).
/// </summary>
/// <typeparam name="T">Return type. Must match the attribute.</typeparam>
/// <param name="window">The window.</param>
/// <param name="attribute">The attribute.</param>
/// <returns>Value of the windows attribute.</returns>
public static T GetWindowAttribute <T>(this IWin32Window window, GetWindowAttr attribute) where T : struct
{
if (window == null)
{
throw new ArgumentNullException(nameof(window));
}
using (var ptr = SafeHGlobalHandle.AllocHGlobal <T>())
{
NativeMethods.DwmGetWindowAttribute(window.Handle, (NativeMethods.DWMWINDOWATTRIBUTE)attribute, ptr, ptr.Size);
return(ptr.ToStructure <T>());
}
}
/// <summary>
/// Sets the specified window attribute through the Desktop Window Manager (DWM).
/// </summary>
/// <param name="window">The window.</param>
/// <param name="attribute">The attribute.</param>
/// <param name="value">The value.</param>
public static void SetWindowAttribute(this IWin32Window window, SetWindowAttr attribute, object value)
{
if (window == null)
{
throw new ArgumentNullException(nameof(window));
}
if (value == null)
{
throw new ArgumentNullException(nameof(value));
}
using (var ptr = new SafeHGlobalHandle(value))
NativeMethods.DwmSetWindowAttribute(window.Handle, (NativeMethods.DWMWINDOWATTRIBUTE)attribute, ptr, ptr.Size);
}
/// <summary>
/// Allocates from unmanaged memory to represent a structure with a
/// variable length array at the end and marshal these structure
/// elements. It is the callers responsibility to marshal what precedes
/// the trailing array into the unmanaged memory. ONLY structures with
/// attribute StructLayout of LayoutKind.Sequential are supported.
/// </summary>
/// <typeparam name="T">Type of the trailing array of structures</typeparam>
/// <param name="prefixBytes">Number of bytes preceding the trailing array of structures</param>
/// <param name="values">Collection of structure objects</param>
/// <param name="count">Number of items in <paramref name="values"/>.</param>
/// <returns>SafeHGlobalHandle object to an native (unmanaged) structure with a trail array of structures</returns>
public static SafeHGlobalHandle AllocHGlobal <T>(int prefixBytes, IEnumerable <T> values, int count) where T : struct
{
Debug.Assert(typeof(T).StructLayoutAttribute?.Value == LayoutKind.Sequential);
var result = new SafeHGlobalHandle(prefixBytes + Marshal.SizeOf(typeof(T)) * count);
var ptr = new IntPtr(result.handle.ToInt32() + prefixBytes);
foreach (var value in values)
{
Marshal.StructureToPtr(value, ptr, false);
ptr = new IntPtr(ptr.ToInt32() + Marshal.SizeOf(typeof(T)));
}
return(result);
}
