（七十七）c#Winform自定义控件-采样控件-HZHControls

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

欢迎前来交流探讨： 企鹅群568015492 

来都来了，点个【推荐】再走吧，谢谢

NuGet

Install-Package HZH_Controls

目录

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

用处及效果

注意观察各个控件交叠的地方，是不是发现他们没有遮挡？这就是这个控件的妙处了。

准备工作

先说明一下这个控件的作用，很多时候我们需要一个图片类型的控件，但是有需要密集的放在一起，如果单纯的设置背景图或image的话  交叠在一起的部分就会存在遮挡现象，所有就有了这个控件。

该控件可以根据设置的采样图片来裁剪有用的绘图区域，这样的好处就是在交叠的时候，无用区域不会遮挡。

这个用GDI+画的，另外也用到了一点三角函数，不明白的话 可以先百度下

开始

添加一个类UCSampling ，继承UserControl

添加属性

   /// <summary>
         /// The sampling imag
         /// </summary>
         private Bitmap samplingImag = null;
         /// <summary>
         /// Gets or sets the sampling imag.
         /// </summary>
         /// <value>The sampling imag.</value>
         [Browsable(true), Category("自定义属性"), Description("采样图片"), Localizable(true)]
         public Bitmap SamplingImag
         {
             get { return samplingImag; }
             set
             {
                 samplingImag = value;
                 ResetBorderPath();
                 Invalidate();
             }
         }

         /// <summary>
         /// The transparent
         /// </summary>
         private Color? transparent = null;

         /// <summary>
         /// Gets or sets the transparent.
         /// </summary>
         /// <value>The transparent.</value>
         [Browsable(true), Category("自定义属性"), Description("透明色，如果为空，则使用0,0坐标处的颜色"), Localizable(true)]
         public Color? Transparent
         {
             get { return transparent; }
             set
             {
                 transparent = value;
                 ResetBorderPath();
                 Invalidate();
             }
         }

         /// <summary>
         /// The alpha
         /// </summary>
         private int alpha = ;

         /// <summary>
         /// Gets or sets the alpha.
         /// </summary>
         /// <value>The alpha.</value>
         [Browsable(true), Category("自定义属性"), Description("当作透明色的透明度，小于此透明度的颜色将被认定为透明，0-255"), Localizable(true)]
         public int Alpha
         {
             get { return alpha; }
             set
             {
                 if (value <  || value > )
                     return;
                 alpha = value;
                 ResetBorderPath();
                 Invalidate();
             }
         }

         /// <summary>
         /// The color threshold
         /// </summary>
         private int colorThreshold = ;

         /// <summary>
         /// Gets or sets the color threshold.
         /// </summary>
         /// <value>The color threshold.</value>
         [Browsable(true), Category("自定义属性"), Description("透明色颜色阀值"), Localizable(true)]
         public int ColorThreshold
         {
             get { return colorThreshold; }
             set
             {
                 colorThreshold = value;
                 ResetBorderPath();
                 Invalidate();
             }
         }

         /// <summary>
         /// The bit cache
         /// </summary>
         private Bitmap _bitCache;

在大小改变或图片改变时重新计算边界

  /// <summary>
         /// The m border path
         /// </summary>
         GraphicsPath m_borderPath = new GraphicsPath();

         /// <summary>
         /// Handles the SizeChanged event of the UCSampling 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 UCSampling_SizeChanged(object sender, EventArgs e)
         {
             ResetBorderPath();
         }

         /// <summary>
         /// Resets the border path.
         /// </summary>
         private void ResetBorderPath()
         {
             if (samplingImag == null)
             {
                 m_borderPath = this.ClientRectangle.CreateRoundedRectanglePath();
             }
             else
             {
                 var bit = new Bitmap(this.ClientRectangle.Width, this.ClientRectangle.Height);
                 using (var bitg = Graphics.FromImage(bit))
                 {
                     bitg.DrawImage(samplingImag, this.ClientRectangle, , , samplingImag.Width, samplingImag.Height, GraphicsUnit.Pixel);
                 }
                 _bitCache = bit;
                 m_borderPath = new GraphicsPath();
                 List<PointF> lstPoints = GetBorderPoints(bit, transparent ?? samplingImag.GetPixel(, ));
                 m_borderPath.AddLines(lstPoints.ToArray());
                 m_borderPath.CloseAllFigures();
             }
         }

         /// <summary>
         /// Gets the border points.
         /// </summary>
         /// <param name="bit">The bit.</param>
         /// <param name="transparent">The transparent.</param>
         /// <returns>List&lt;PointF&gt;.</returns>
         private List<PointF> GetBorderPoints(Bitmap bit, Color transparent)
         {
             float diameter = (float)Math.Sqrt(bit.Width * bit.Width + bit.Height * bit.Height);
             int intSplit = ;
             intSplit = (int)( - (diameter - ) / );
             if (intSplit < )
                 intSplit = ;
             List<PointF> lstPoint = new List<PointF>();
             for (int i = ; i < ; i += intSplit)
             {
                 for (int j = (int)diameter / ; j > ; j--)
                 {
                     Point p = GetPointByAngle(i, j, new PointF(bit.Width / , bit.Height / ));
                     if (p.X <  || p.Y <  || p.X >= bit.Width || p.Y >= bit.Height)
                         continue;
                     Color _color = bit.GetPixel(p.X, p.Y);
                     if (!(((int)_color.A) <= alpha || IsLikeColor(_color, transparent)))
                     {
                         if (!lstPoint.Contains(p))
                         {
                             lstPoint.Add(p);
                         }
                         break;
                     }
                 }
             }
             return lstPoint;
         }

         /// <summary>
         /// Determines whether [is like color] [the specified color1].
         /// </summary>
         /// <param name="color1">The color1.</param>
         /// <param name="color2">The color2.</param>
         /// <returns><c>true</c> if [is like color] [the specified color1]; otherwise, <c>false</c>.</returns>
         private bool IsLikeColor(Color color1, Color color2)
         {
             var cv = Math.Sqrt(Math.Pow((color1.R - color2.R), ) + Math.Pow((color1.G - color2.G), ) + Math.Pow((color1.B - color2.B), ));
             if (cv <= colorThreshold)
                 return true;
             else
                 return false;
         }

  #region 根据角度得到坐标    English:Get coordinates from angles
         /// <summary>
         /// 功能描述:根据角度得到坐标    English:Get coordinates from angles
         /// 作　　者:HZH
         /// 创建日期:2019-09-28 11:56:25
         /// 任务编号:POS
         /// </summary>
         /// <param name="angle">angle</param>
         /// <param name="radius">radius</param>
         /// <param name="origin">origin</param>
         /// <returns>返回值</returns>
         private Point GetPointByAngle(float angle, float radius, PointF origin)
         {
             float y = origin.Y + (float)Math.Sin(Math.PI * (angle / 180.00F)) * radius;
             float x = origin.X + (float)Math.Cos(Math.PI * (angle / 180.00F)) * radius;
             return new Point((int)x, (int)y);
         }
         #endregion

取边界的思路如下：

1，以控件中心为原点，按照一定的角度顺时针依次进行旋转，

2、每次旋转后，按照此角度从外向内，找到第一个不是透明的点记录下来，这就是外边界点

这个取边界算法感觉并不是太好，如果哪位小伙伴有更好的算法，希望可以探讨一下

重绘

   protected override void OnPaint(PaintEventArgs e)
         {
             base.OnPaint(e);
             e.Graphics.SetGDIHigh();

             this.Region = new System.Drawing.Region(m_borderPath);

             if (_bitCache != null)
                 e.Graphics.DrawImage(_bitCache, , );

         }

最后的话

如果你喜欢的话，请到 https://gitee.com/kwwwvagaa/net_winform_custom_control 点个星星吧