问题
I'm trying to drop a shadow around the whole form just like the first picture, except that that is a WPF, not a WinForm. now I want to drop the same shadow on a winform.
This is what I want..¬
Not this..¬
回答1:
In WinForms, you can just override the form's protected CreateParams property and add the CS_DROPSHADOW flag to the class styles. For example:
public class ShadowedForm : Form { protected override CreateParams CreateParams { get { const int CS_DROPSHADOW = 0x20000; CreateParams cp = base.CreateParams; cp.ClassStyle |= CS_DROPSHADOW; return cp; } } // ... other code ... } But, a couple of caveats…
This flag works only on top-level windows. In Win32-speak, that means overlapped and popup windows. It has no effect on child windows (e.g. controls). I thought I remembered hearing somewhere that this limitation had been removed from Windows 8, but I can't find a link confirming this and I don't have Windows 8 installed for testing purposes.
It is possible that the user has disabled this feature altogether. If so, you won't get drop shadows, no matter how you ask for them. That's by design. Your application should not try and override this request. You can determine whether drop shadows are enabled or disabled by P/Invoking the SystemParametersInfo function and passing the
SPI_GETDROPSHADOWflag.The Aero theme also adds shadows to top-level windows. This effect is separate and distinct from
CS_DROPSHADOW, and works only when Aero is enabled. There's no way to turn it off and on for individual windows. Moreover, since the Aero theme has been removed from Windows 8, it won't ever have these shadows.
回答2:
Here's my C# implementation. It's similar to Al. Petro's, but you'll notice that when you lose focus and regain focus, the shadow repaints itself.
I've also added code to allow mouse-dragging.
public partial class Form1: Form { [DllImport("Gdi32.dll", EntryPoint = "CreateRoundRectRgn")] private static extern IntPtr CreateRoundRectRgn ( int nLeftRect, // x-coordinate of upper-left corner int nTopRect, // y-coordinate of upper-left corner int nRightRect, // x-coordinate of lower-right corner int nBottomRect, // y-coordinate of lower-right corner int nWidthEllipse, // height of ellipse int nHeightEllipse // width of ellipse ); [DllImport("dwmapi.dll")] public static extern int DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS pMarInset); [DllImport("dwmapi.dll")] public static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize); [DllImport("dwmapi.dll")] public static extern int DwmIsCompositionEnabled(ref int pfEnabled); private bool m_aeroEnabled; // variables for box shadow private const int CS_DROPSHADOW = 0x00020000; private const int WM_NCPAINT = 0x0085; private const int WM_ACTIVATEAPP = 0x001C; public struct MARGINS // struct for box shadow { public int leftWidth; public int rightWidth; public int topHeight; public int bottomHeight; } private const int WM_NCHITTEST = 0x84; // variables for dragging the form private const int HTCLIENT = 0x1; private const int HTCAPTION = 0x2; protected override CreateParams CreateParams { get { m_aeroEnabled = CheckAeroEnabled(); CreateParams cp = base.CreateParams; if (!m_aeroEnabled) cp.ClassStyle |= CS_DROPSHADOW; return cp; } } private bool CheckAeroEnabled() { if (Environment.OSVersion.Version.Major >= 6) { int enabled = 0; DwmIsCompositionEnabled(ref enabled); return (enabled == 1) ? true : false; } return false; } protected override void WndProc(ref Message m) { switch (m.Msg) { case WM_NCPAINT: // box shadow if (m_aeroEnabled) { var v = 2; DwmSetWindowAttribute(this.Handle, 2, ref v, 4); MARGINS margins = new MARGINS() { bottomHeight = 1, leftWidth = 1, rightWidth = 1, topHeight = 1 }; DwmExtendFrameIntoClientArea(this.Handle, ref margins); } break; default: break; } base.WndProc(ref m); if (m.Msg == WM_NCHITTEST && (int)m.Result == HTCLIENT) // drag the form m.Result = (IntPtr)HTCAPTION; } public Form1() { m_aeroEnabled = false; this.FormBorderStyle = FormBorderStyle.None; InitializeComponent(); } } 回答3:
Humm ,,, Just past the code and you will get the windows 7 Drop Shadow like this >>> http://marcin.floryan.pl/wp-content/uploads/2010/08/WPF-Window-native-shadow.png
Imports System.Runtime.InteropServices Public Class IMSS_SplashScreen Private aeroEnabled As Boolean Protected Overrides ReadOnly Property CreateParams() As CreateParams Get CheckAeroEnabled() Dim cp As CreateParams = MyBase.CreateParams If Not aeroEnabled Then cp.ClassStyle = cp.ClassStyle Or NativeConstants.CS_DROPSHADOW Return cp Else Return cp End If End Get End Property Protected Overrides Sub WndProc(ByRef m As Message) Select Case m.Msg Case NativeConstants.WM_NCPAINT Dim val = 2 If aeroEnabled Then NativeMethods.DwmSetWindowAttribute(Handle, 2, val, 4) Dim bla As New NativeStructs.MARGINS() With bla .bottomHeight = 1 .leftWidth = 1 .rightWidth = 1 .topHeight = 1 End With NativeMethods.DwmExtendFrameIntoClientArea(Handle, bla) End If Exit Select End Select MyBase.WndProc(m) End Sub Private Sub CheckAeroEnabled() If Environment.OSVersion.Version.Major >= 6 Then Dim enabled As Integer = 0 Dim response As Integer = NativeMethods.DwmIsCompositionEnabled(enabled) aeroEnabled = (enabled = 1) Else aeroEnabled = False End If End Sub End Class Public Class NativeStructs Public Structure MARGINS Public leftWidth As Integer Public rightWidth As Integer Public topHeight As Integer Public bottomHeight As Integer End Structure End Class Public Class NativeMethods <DllImport("dwmapi")> _ Public Shared Function DwmExtendFrameIntoClientArea(ByVal hWnd As IntPtr, ByRef pMarInset As NativeStructs.MARGINS) As Integer End Function <DllImport("dwmapi")> _ Friend Shared Function DwmSetWindowAttribute(ByVal hwnd As IntPtr, ByVal attr As Integer, ByRef attrValue As Integer, ByVal attrSize As Integer) As Integer End Function <DllImport("dwmapi.dll")> _ Public Shared Function DwmIsCompositionEnabled(ByRef pfEnabled As Integer) As Integer End Function End Class Public Class NativeConstants Public Const CS_DROPSHADOW As Integer = &H20000 Public Const WM_NCPAINT As Integer = &H85 End Class 回答4:
As far as I know, there is no direct way of doing this in WinForms.
Instead, you can follow this step by step:
1) Create an image having the desired drop shadow using photoshop or any other tool.
2) Use this image as background image of your form.
3) Set FormBorderStyle property of the form to None.
4) You are done!
5) Note: Make sure to save the image in proper format(such as png) so that the drop shadow effect could work.
来源：https://stackoverflow.com/questions/16493698/drop-shadow-on-a-borderless-winform