无边框winform窗体阴影

Question

我有一个无边框窗口窗体，我使用下面的代码在它后面创建了一个阴影。
但是，当我单击父窗体时，阴影消失了。

任何人都可以帮助我了解如何在单击另一个表单/父表单时保持阴影吗？
阴影对不同的窗口（例如chrome）是可见的，但对它的父窗体不可见

（我尝试了谷歌但找不到任何东西）

更新
我确实注意到，如果我最小化窗口并再次最大化它，阴影确实会回来

我的代码

    private const int CS_DROPSHADOW = 0x00020000;
    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams cp = base.CreateParams;
            cp.ClassStyle |= CS_DROPSHADOW;
            return cp;
        }
    }

提前致谢

Answer 1

请尝试以下步骤并恢复任何错误：

将以下代码添加到名为 DropShadow.cs 的新代码文件中；

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Core
{
    public class DropShadow
    {
        #region Shadowing

        #region Fields

        private bool _isAeroEnabled = false;
        private bool _isDraggingEnabled = false;
        private const int WM_NCHITTEST = 0x84;
        private const int WS_MINIMIZEBOX = 0x20000;
        private const int HTCLIENT = 0x1;
        private const int HTCAPTION = 0x2;
        private const int CS_DBLCLKS = 0x8;
        private const int CS_DROPSHADOW = 0x00020000;
        private const int WM_NCPAINT = 0x0085;
        private const int WM_ACTIVATEAPP = 0x001C;

        #endregion

        #region Structures

        [EditorBrowsable(EditorBrowsableState.Never)]
        public struct MARGINS
        {
            public int leftWidth;
            public int rightWidth;
            public int topHeight;
            public int bottomHeight;
        }

        #endregion

        #region Methods

        #region Public

        [DllImport("dwmapi.dll")]
        [EditorBrowsable(EditorBrowsableState.Never)]
        public static extern int DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS pMarInset);

        [DllImport("dwmapi.dll")]
        [EditorBrowsable(EditorBrowsableState.Never)]
        public static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize);

        [DllImport("dwmapi.dll")]
        [EditorBrowsable(EditorBrowsableState.Never)]
        public static extern int DwmIsCompositionEnabled(ref int pfEnabled);

        [EditorBrowsable(EditorBrowsableState.Never)]
        public static bool IsCompositionEnabled()
        {
            if (Environment.OSVersion.Version.Major < 6) return false;

            bool enabled;
            DwmIsCompositionEnabled(out enabled);

            return enabled;
        }

        #endregion

        #region Private

        [DllImport("dwmapi.dll")]
        private static extern int DwmIsCompositionEnabled(out bool enabled);

        [DllImport("Gdi32.dll", EntryPoint = "CreateRoundRectRgn")]
        private static extern IntPtr CreateRoundRectRgn
        (
            int nLeftRect,
            int nTopRect,
            int nRightRect,
            int nBottomRect,
            int nWidthEllipse,
            int nHeightEllipse
         );

        private bool CheckIfAeroIsEnabled()
        {
            if (Environment.OSVersion.Version.Major >= 6)
            {
                int enabled = 0;
                DwmIsCompositionEnabled(ref enabled);

                return (enabled == 1) ? true : false;
            }
            return false;
        }

        #endregion

        #region Overrides

        public void ApplyShadows(Form form)
        {
            var v = 2;

            DwmSetWindowAttribute(form.Handle, 2, ref v, 4);

            MARGINS margins = new MARGINS()
            {
                bottomHeight = 1,
                leftWidth = 0,
                rightWidth = 0,
                topHeight = 0
            };

            DwmExtendFrameIntoClientArea(form.Handle, ref margins);
        }

        #endregion

        #endregion

        #endregion
    }
}

在您的表单中，在 InitializeComponent(); 下方添加这一行

(new Core.DropShadow()).ApplyShadows(this);