本文实现在winform项目实现网页div+css关透明效果，挺帅的，在网页中要实现div的半透明遮罩层效果不难，在winform项目就不是这么容易了，下面我们来看下效果图先：   正常时：

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下面我们来实现上图的效果控件源码：

using System;using System.Collections.Generic;using System.Text;using System.Drawing;using System.Windows.Forms;using System.ComponentModel;namespace MyOpaqueLayer{    [ToolboxBitmap(typeof(MyOpaqueLayer))]    public class MyOpaqueLayer : System.Windows.Forms.Control    {        private bool _transparentBG = true;        private int _alpha = 125;        private System.ComponentModel.Container components = new System.ComponentModel.Container();        public MyOpaqueLayer()            : this(125, true)        {        }        public MyOpaqueLayer(int Alpha, bool showLoadingImage)        {            SetStyle(System.Windows.Forms.ControlStyles.Opaque, true);            base.CreateControl();            this._alpha = Alpha;            ;            if (showLoadingImage)            {                PictureBox pictureBox_Loading = new PictureBox();                pictureBox_Loading.BackColor = System.Drawing.Color.White;                pictureBox_Loading.Image = global::MyOpaqueLayer.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);                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);        }        /// 
        /// 自定义绘制窗体        /// 
        ///         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 |= 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")]        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();            }        }    }}文章来自学IT网：http://www.xueit.com/html/2010-01-08/21-1076980691437.html

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