using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace MyUserControl

{

    [ToolboxItem(false), Browsable(false), Description("用于屏蔽用户界面的控件;")]

    public partial class MaskLayer : Control

    {

        private int alpha;

        private Boolean bShow = true;

        Timer timer = new Timer();

        public MaskLayer()

        {

            timer.Interval = ;

            timer.Tick += Timer1_Tick;

            timer.Start();

            SetStyle(ControlStyles.UserPaint, true);

            SetStyle(ControlStyles.AllPaintingInWmPaint, true); // 禁止擦除背景.

            SetStyle(ControlStyles.DoubleBuffer, true); // 双缓冲

            alpha = ;

            //SetStyle(System.Windows.Forms.ControlStyles.Opaque, true);

        }

        private void Timer1_Tick(object sender, EventArgs e)

        {

            if (bShow)

                ShowMask(bShow);

            else

            {

                ShowMask(bShow);

                BackgroundImage = null;

            }

        }

        private delegate void ShowMaskCallback(Boolean bShow);

        private void ShowMask(Boolean bShow)

        {

            // InvokeRequired需要比较调用线程ID和创建线程ID

            // 如果它们不相同则返回true

            if (this.InvokeRequired)

            {

                ShowMaskCallback d = new ShowMaskCallback(ShowMask);

                this.Invoke(d, new object[] { bShow });

            }

            else

            {

                if (bShow)

                    this.Show();

                else

                    this.Hide();

            }

        }

        //显示线程

        public void DelayShowMaskByScreenCopy(Control parentControl)

        {

            this.BackColor = Color.Black;

            this.Left = ;

            this.Top = ;

            this.Width = parentControl.Width;

            this.Height = parentControl.Height;

            this.Parent = parentControl;

            if (this.BackgroundImage == null)

            {

                Rectangle rect = parentControl.ClientRectangle;

                Rectangle sRect = parentControl.RectangleToScreen(rect);

                Bitmap bit = new Bitmap(rect.Width, rect.Height);//实例化一个和窗体一样大的bitmap

                Graphics g = Graphics.FromImage(bit);

                g.CompositingQuality = CompositingQuality.HighQuality;//质量设为最高

                g.CopyFromScreen(sRect.Left, sRect.Top, , , new Size(this.Width, this.Height));

                this.BackgroundImage = bit;

            }

            bShow = true;

        }

        public void DelayShowMaskByColorFill(Color color,Control parentControl)

        {

            this.BackColor = Color.Black;

            this.Left = ;

            this.Top = ;

            this.Width = parentControl.Width;

            this.Height = parentControl.Height;

            this.Parent = parentControl;

            SetStyle(ControlStyles.AllPaintingInWmPaint, false); // 擦除背景.有轻微闪烁现象

            if (this.BackgroundImage == null)

            {

                Rectangle rect = parentControl.ClientRectangle;

                Rectangle sRect = parentControl.RectangleToScreen(rect);

                Bitmap bit = new Bitmap(rect.Width, rect.Height);//实例化一个和窗体一样大的bitmap

                Graphics g = Graphics.FromImage(bit);

                g.CompositingQuality = CompositingQuality.HighQuality;//质量设为最高

                g.FillRectangle(new SolidBrush(Color.FromArgb(alpha, color)), this.ClientRectangle);

                this.BackgroundImage = bit;

            }

            bShow = true;

        }

        public void DelayHide()

        {

            bShow = false;

        }

        protected override void OnPaintBackground(PaintEventArgs e)

        {

            return;

        }

        protected override void OnPaint(PaintEventArgs e)

        {

            Bitmap bmp = new Bitmap(this.Width, this.Height);

            Graphics g = Graphics.FromImage(bmp);

            g.DrawImage(BackgroundImage, , , this.Width, this.Height);

            Color color = Color.FromArgb(alpha, this.BackColor);

            using (SolidBrush brush = new SolidBrush(color))

            {

                g.FillRectangle(brush, , , this.Size.Width, this.Size.Height);

            }

            if (!this.DesignMode)

            {

                using (Pen pen = new Pen(color))

                {

                    g.DrawRectangle(pen, , , this.Width, this.Height);

                }

            }

            else

                g.DrawRectangle(Pens.Black, , , this.Width - , this.Height - );

            e.Graphics.DrawImage(bmp, , );

            g.Dispose();

            bmp.Dispose();

        }

        protected override CreateParams CreateParams

        {

            get

            {

                const int CS_NOCLOSE = 0x200;

                CreateParams cp = base.CreateParams;

                cp.ExStyle |= 0x00000020;

                cp.ClassStyle = cp.ClassStyle | CS_NOCLOSE;

                return cp;

            }

        }

        public int Alpha

        {

            get

            {

                return alpha;

            }

            set

            {

                if (value < ) alpha = ;

                else if (value > ) alpha = ;

                else alpha = value;

                this.Invalidate();

            }

        }

    }

}

MaskLayer maskLayer = new MaskLayer();
/****
//*****
*/
private void ShowMask()

{

    maskLayer.DelayShowMaskByScreenCopy(panelEx1);//panelEx1是被蒙版的控件。

}

private void HideMask()

{

    maskLayer.DelayHide();

}