FormBorderStyle.Noneのフォームは、枠がなくなると同時に、周囲の影も消えてしまう。
下記コードを適用することで、Aeroの影を復活することができる。
public partial class Form1 : Form
{
#region Win32API
[StructLayout(LayoutKind.Sequential)]
private struct MARGINS
{
public int leftWidth;
public int rightWidth;
public int topHeight;
public int bottomHeight;
}
[DllImport("dwmapi.dll")]
private static extern int DwmExtendFrameIntoClientArea(IntPtr hwnd, ref MARGINS margins);
private enum DWMWINDOWATTRIBUTE : uint
{
NCRenderingEnabled = 1,
NCRenderingPolicy,
TransitionsForceDisabled,
AllowNCPaint,
CaptionButtonBounds,
NonClientRtlLayout,
ForceIconicRepresentation,
Flip3DPolicy,
ExtendedFrameBounds,
HasIconicBitmap,
DisallowPeek,
ExcludedFromPeek,
Cloak,
Cloaked,
FreezeRepresentation
}
[DllImport("dwmapi.dll", PreserveSig = true)]
private static extern int DwmSetWindowAttribute(IntPtr hwnd, DWMWINDOWATTRIBUTE attr, ref int attrValue, int attrSize);
[DllImport("dwmapi.dll")]
private static extern int DwmIsCompositionEnabled(out bool enabled);
const int WM_NCPAINT = 0x85;
#endregion
public Form1()
{
InitializeComponent();
this.FormBorderStyle = FormBorderStyle.None;
}
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
protected override void WndProc(ref Message m)
{
switch (m.Msg)
{
case WM_NCPAINT:
// デザイン時は処理しない
if (!DesignMode)
{
// Vista以降のOSのみ
if (Environment.OSVersion.Version.Major >= 6)
{
// Aeroが使用可能か確認
bool bolAeroEnabled = false;
DwmIsCompositionEnabled(out bolAeroEnabled);
if (bolAeroEnabled == true)
{
int intAttrValue = 2;
int intAttrSize = sizeof(int);
DwmSetWindowAttribute(this.Handle, DWMWINDOWATTRIBUTE.NCRenderingPolicy, ref intAttrValue, intAttrSize);
MARGINS objMargins = new MARGINS()
{
leftWidth = 1,
rightWidth = 1,
topHeight = 1,
bottomHeight = 1
};
DwmExtendFrameIntoClientArea(this.Handle, ref objMargins);
}
}
}
break;
}
base.WndProc(ref m);
}
}
余談：WPFの場合は、GlowWindowを使うと綺麗にできる。
