（七十八）c#Winform自定义控件-倒影组件

官网

http://www.hzhcontrols.com

前提

入行已经7,8年了，一直想做一套漂亮点的自定义控件，于是就有了本系列文章。

GitHub：https://github.com/kwwwvagaa/NetWinformControl

码云：https://gitee.com/kwwwvagaa/net_winform_custom_control.git

如果觉得写的还行，请点个 star 支持一下吧

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NuGet

Install-Package HZH_Controls

目录

https://www.cnblogs.com/bfyx/p/11364884.html

用处及效果

准备工作

GDI+画图，不了解先百度

开始

思路：

控件扩展属性，在组件中对需要显示倒影的控件的父控件添加Paint事件，在Paint事件中绘制控件，并旋转180，然后画到父控件上，然后再覆盖一层渐变色，完美。

添加一个类ShadowComponent 继承Component，实现 IExtenderProvider接口，扩展属性

代码比较少，直接放上来了

 /// <summary>
         /// The m control cache
         /// </summary>
         Dictionary<Control, bool> m_controlCache = new Dictionary<Control, bool>();

         #region 构造函数    English:Constructor
         /// <summary>
         /// Initializes a new instance of the <see cref="ShadowComponent" /> class.
         /// </summary>
         public ShadowComponent()
         {

         }

         /// <summary>
         /// Initializes a new instance of the <see cref="ShadowComponent" /> class.
         /// </summary>
         /// <param name="container">The container.</param>
         public ShadowComponent(IContainer container)
             : this()
         {
             container.Add(this);
         }
         #endregion

         /// <summary>
         /// 指定此对象是否可以将其扩展程序属性提供给指定的对象。
         /// </summary>
         /// <param name="extendee">要接收扩展程序属性的 <see cref="T:System.Object" />。</param>
         /// <returns>如果此对象可以扩展程序属性提供给指定对象，则为 true；否则为 false。</returns>
         public bool CanExtend(object extendee)
         {
             if (extendee is Control && !(extendee is Form))
                 return true;
             return false;
         }

         /// <summary>
         /// Gets the show shadow.
         /// </summary>
         /// <param name="control">The control.</param>
         /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
         [Browsable(true), Category("自定义属性"), Description("是否显示倒影"), DisplayName("ShowShadow"), Localizable(true)]
         public bool GetShowShadow(Control control)
         {
             if (m_controlCache.ContainsKey(control))
                 return m_controlCache[control];
             else
                 return false;
         }

         /// <summary>
         /// Sets the show shadow.
         /// </summary>
         /// <param name="control">The control.</param>
         /// <param name="isShowShadow">if set to <c>true</c> [is show shadow].</param>
         public void SetShowShadow(Control control, bool isShowShadow)
         {
             control.ParentChanged += control_ParentChanged;
             m_controlCache[control] = isShowShadow;
         }

         /// <summary>
         /// Handles the ParentChanged event of the control control.
         /// </summary>
         /// <param name="sender">The source of the event.</param>
         /// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
         void control_ParentChanged(object sender, EventArgs e)
         {
             Control control = sender as Control;
             if (control.Parent != null && m_controlCache[control])
             {
                 if (!lstPaintEventControl.Contains(control.Parent))
                 {
                     lstPaintEventControl.Add(control.Parent);
                     Type type = control.Parent.GetType();
                     System.Reflection.PropertyInfo pi = type.GetProperty("DoubleBuffered", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
                     pi.SetValue(control.Parent, true, null);
                     control.Parent.Paint += Parent_Paint;
                 }
             }
         }

         /// <summary>
         /// The LST paint event control
         /// </summary>
         List<Control> lstPaintEventControl = new List<Control>();
         /// <summary>
         /// The shadow height
         /// </summary>
         private float shadowHeight = 0.3f;

         /// <summary>
         /// Gets or sets the height of the shadow.
         /// </summary>
         /// <value>The height of the shadow.</value>
         [Browsable(true), Category("自定义属性"), Description("倒影高度，0-1"), Localizable(true)]
         public float ShadowHeight
         {
             get { return shadowHeight; }
             set { shadowHeight = value; }
         }
         /// <summary>
         /// The BLN loading
         /// </summary>
         bool blnLoading = false;
         /// <summary>
         /// Handles the Paint event of the Parent control.
         /// </summary>
         /// <param name="sender">The source of the event.</param>
         /// <param name="e">The <see cref="PaintEventArgs"/> instance containing the event data.</param>
         void Parent_Paint(object sender, PaintEventArgs e)
         {
             if (blnLoading)
                 return;
             if (shadowHeight > )
             {
                 var control = sender as Control;
                 var lst = m_controlCache.Where(p => p.Key.Parent == control && p.Value);
                 if (lst != null && lst.Count() > )
                 {
                     blnLoading = true;
                     e.Graphics.SetGDIHigh();
                     foreach (var item in lst)
                     {
                         Control _control = item.Key;

                         using (Bitmap bit = new Bitmap(_control.Width, _control.Height))
                         {
                             _control.DrawToBitmap(bit, _control.ClientRectangle);
                             using (Bitmap bitNew = new Bitmap(bit.Width, (int)(bit.Height * shadowHeight)))
                             {
                                 using (var g = Graphics.FromImage(bitNew))
                                 {
                                     g.DrawImage(bit, new RectangleF(, , bitNew.Width, bitNew.Height), new RectangleF(, bit.Height - bit.Height * shadowHeight, bit.Width, bit.Height * shadowHeight), GraphicsUnit.Pixel);
                                 }
                                 bitNew.RotateFlip(RotateFlipType.Rotate180FlipNone);
                                 e.Graphics.DrawImage(bitNew, new Point(_control.Location.X, _control.Location.Y + _control.Height + ));
                                 Color bgColor = GetParentColor(_control);
                                 LinearGradientBrush lgb = new LinearGradientBrush(new Rectangle(_control.Location.X, _control.Location.Y + _control.Height + , bitNew.Width, bitNew.Height), Color.FromArgb(, bgColor), bgColor, 90f);   //75f 表示角度
                                 e.Graphics.FillRectangle(lgb, new Rectangle(new Point(_control.Location.X, _control.Location.Y + _control.Height + ), bitNew.Size));
                             }
                         }
                     }
                 }
             }
             blnLoading = false;
         }

         /// <summary>
         /// Gets the color of the parent.
         /// </summary>
         /// <param name="c">The c.</param>
         /// <returns>Color.</returns>
         private Color GetParentColor(Control c)
         {
             if (c.Parent.BackColor != Color.Transparent)
             {
                 return c.Parent.BackColor;
             }
             return GetParentColor(c.Parent);
         }

最后的话

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