C#实现Winform自定义半透明遮罩层

using System;
using System.Drawing;
using System.Windows.Forms;
using System.ComponentModel;

namespace MyOpaqueLayer
{
    /// <summary>
    /// 自定义控件:半透明控件
    /// </summary>
    /* 
     * [ToolboxBitmap(typeof(MyOpaqueLayer))]
     * 用于指定当把你做好的自定义控件添加到工具栏时，工具栏显示的图标。
     * 正确写法应该是
     * [ToolboxBitmap(typeof(XXXXControl),"xxx.bmp")]
     * 其中XXXXControl是你的自定义控件，"xxx.bmp"是你要用的图标名称。
    */
    [ToolboxBitmap(typeof(MyOpaqueLayer))]
    public class MyOpaqueLayer : System.Windows.Forms.Control
    {
        private bool _transparentBG = true;//是否使用透明
        private int _alpha = 125;//设置透明度
        
        private System.ComponentModel.Container components = new System.ComponentModel.Container();

        public MyOpaqueLayer()
            : this(125, true)
        {
        }

        public MyOpaqueLayer(int Alpha, bool IsShowLoadingImage)
        {
            SetStyle(System.Windows.Forms.ControlStyles.Opaque, true);
            base.CreateControl();

            this._alpha = Alpha;
            if (IsShowLoadingImage)
            {
                PictureBox pictureBox_Loading = new PictureBox();
                pictureBox_Loading.BackColor = System.Drawing.Color.White;
                pictureBox_Loading.Image = 加载中.Properties.Resources.loading;  
                pictureBox_Loading.Name = "pictureBox_Loading";
                pictureBox_Loading.Size = new System.Drawing.Size(48, 48);
                pictureBox_Loading.SizeMode = System.Windows.Forms.PictureBoxSizeMode.AutoSize;
                Point Location = new Point(this.Location.X + (this.Width - pictureBox_Loading.Width) / 2, this.Location.Y + (this.Height - pictureBox_Loading.Height) / 2);//居中
                pictureBox_Loading.Location = Location;
                pictureBox_Loading.Anchor = AnchorStyles.None;
                this.Controls.Add(pictureBox_Loading);
            }
        }


        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (!((components == null)))
                {
                    components.Dispose();
                }
            }
            base.Dispose(disposing);
        }

        /// <summary>
        /// 自定义绘制窗体
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
        {
            float vlblControlWidth;
            float vlblControlHeight;

            Pen labelBorderPen;
            SolidBrush labelBackColorBrush;

            if (_transparentBG)
            {
                Color drawColor = Color.FromArgb(this._alpha, this.BackColor);
                labelBorderPen = new Pen(drawColor, 0);
                labelBackColorBrush = new SolidBrush(drawColor);
            }
            else
            {
                labelBorderPen = new Pen(this.BackColor, 0);
                labelBackColorBrush = new SolidBrush(this.BackColor);
            }
            base.OnPaint(e);
            vlblControlWidth = this.Size.Width;
            vlblControlHeight = this.Size.Height;
            e.Graphics.DrawRectangle(labelBorderPen, 0, 0, vlblControlWidth, vlblControlHeight);
            e.Graphics.FillRectangle(labelBackColorBrush, 0, 0, vlblControlWidth, vlblControlHeight);
        }


        protected override CreateParams CreateParams//v1.10 
        {
            get
            {
                CreateParams cp = base.CreateParams;
                cp.ExStyle |= 0x00000020; //0x20;  // 开启 WS_EX_TRANSPARENT,使控件支持透明
                return cp;
            }
        }

        /*
         * [Category("myOpaqueLayer"), Description("是否使用透明,默认为True")]
         * 一般用于说明你自定义控件的属性（Property）。
         * Category用于说明该属性属于哪个分类，Description自然就是该属性的含义解释。
         */
        [Category("MyOpaqueLayer"), Description("是否使用透明,默认为True")]
        public bool TransparentBG
        {
            get
            {
                return _transparentBG;
            }
            set
            {
                _transparentBG = value;
                this.Invalidate();
            }
        }

        [Category("MyOpaqueLayer"), Description("设置透明度")]
        public int Alpha
        {
            get
            {
                return _alpha;
            }
            set
            {
                _alpha = value;
                this.Invalidate();
            }
        }
    }
}

using System;
using System.Windows.Forms;

namespace 加载中
{
    class OpaqueCommand
    {
        private MyOpaqueLayer.MyOpaqueLayer m_OpaqueLayer = null;//半透明蒙板层

        /// <summary>
        /// 显示遮罩层
        /// </summary>
        /// <param name="control">控件</param>
        /// <param name="alpha">透明度</param>
        /// <param name="isShowLoadingImage">是否显示图标</param>
        public void ShowOpaqueLayer(Control control, int alpha, bool isShowLoadingImage)
        {
            try
            {
                if (this.m_OpaqueLayer == null)
                {
                    this.m_OpaqueLayer = new MyOpaqueLayer.MyOpaqueLayer(alpha, isShowLoadingImage);
                    control.Controls.Add(this.m_OpaqueLayer);
                    this.m_OpaqueLayer.Dock = DockStyle.Fill;
                    this.m_OpaqueLayer.BringToFront();
                }
                this.m_OpaqueLayer.Enabled = true;
                this.m_OpaqueLayer.Visible = true;
            }
            catch { }
        }

        /// <summary>
        /// 隐藏遮罩层
        /// </summary>
        public void HideOpaqueLayer()
        {
            try
            {
                if (this.m_OpaqueLayer != null)
                {
                    this.m_OpaqueLayer.Visible = false;
                    this.m_OpaqueLayer.Enabled = false;
                }
            }
            catch(Exception ex)
            {
                //MessageBox.Show(ex.Message);
            }
        }
    }
}