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

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

 1   /// <summary>   2         /// The sampling imag   3         /// </summary>   4         private Bitmap samplingImag = null;   5         /// <summary>   6         /// Gets or sets the sampling imag.   7         /// </summary>   8         /// <value>The sampling imag.</value>   9         [Browsable(true), Category("自定义属性"), Description("采样图片"), Localizable(true)]  10         public Bitmap SamplingImag  11         {  12             get { return samplingImag; }  13             set  14             {  15                 samplingImag = value;  16                 ResetBorderPath();  17                 Invalidate();  18             }  19         }  20   21         /// <summary>  22         /// The transparent  23         /// </summary>  24         private Color? transparent = null;  25   26         /// <summary>  27         /// Gets or sets the transparent.  28         /// </summary>  29         /// <value>The transparent.</value>  30         [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)]  31         public Color? Transparent  32         {  33             get { return transparent; }  34             set  35             {  36                 transparent = value;  37                 ResetBorderPath();  38                 Invalidate();  39             }  40         }  41   42         /// <summary>  43         /// The alpha  44         /// </summary>  45         private int alpha = 50;  46   47         /// <summary>  48         /// Gets or sets the alpha.  49         /// </summary>  50         /// <value>The alpha.</value>  51         [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)]  52         public int Alpha  53         {  54             get { return alpha; }  55             set  56             {  57                 if (value < 0 || value > 255)  58                     return;  59                 alpha = value;  60                 ResetBorderPath();  61                 Invalidate();  62             }  63         }  64   65         /// <summary>  66         /// The color threshold  67         /// </summary>  68         private int colorThreshold = 10;  69   70         /// <summary>  71         /// Gets or sets the color threshold.  72         /// </summary>  73         /// <value>The color threshold.</value>  74         [Browsable(true), Category("自定义属性"), Description("透明色颜色阀值"), Localizable(true)]  75         public int ColorThreshold  76         {  77             get { return colorThreshold; }  78             set  79             {  80                 colorThreshold = value;  81                 ResetBorderPath();  82                 Invalidate();  83             }  84         }  85   86         /// <summary>  87         /// The bit cache  88         /// </summary>  89         private Bitmap _bitCache;

在大小改变或图片改变时重新计算边界

 1  /// <summary>   2         /// The m border path   3         /// </summary>   4         GraphicsPath m_borderPath = new GraphicsPath();   5    6         /// <summary>   7         /// Handles the SizeChanged event of the UCSampling control.   8         /// </summary>   9         /// <param name="sender">The source of the event.</param>  10         /// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>  11         void UCSampling_SizeChanged(object sender, EventArgs e)  12         {  13             ResetBorderPath();  14         }  15   16         /// <summary>  17         /// Resets the border path.  18         /// </summary>  19         private void ResetBorderPath()  20         {  21             if (samplingImag == null)  22             {  23                 m_borderPath = this.ClientRectangle.CreateRoundedRectanglePath(5);  24             }  25             else  26             {  27                 var bit = new Bitmap(this.ClientRectangle.Width, this.ClientRectangle.Height);  28                 using (var bitg = Graphics.FromImage(bit))  29                 {  30                     bitg.DrawImage(samplingImag, this.ClientRectangle, 0, 0, samplingImag.Width, samplingImag.Height, GraphicsUnit.Pixel);  31                 }  32                 _bitCache = bit;  33                 m_borderPath = new GraphicsPath();  34                 List<PointF> lstPoints = GetBorderPoints(bit, transparent ?? samplingImag.GetPixel(0, 0));  35                 m_borderPath.AddLines(lstPoints.ToArray());  36                 m_borderPath.CloseAllFigures();  37             }  38         }  39   40         /// <summary>  41         /// Gets the border points.  42         /// </summary>  43         /// <param name="bit">The bit.</param>  44         /// <param name="transparent">The transparent.</param>  45         /// <returns>List&lt;PointF&gt;.</returns>  46         private List<PointF> GetBorderPoints(Bitmap bit, Color transparent)  47         {  48             float diameter = (float)Math.Sqrt(bit.Width * bit.Width + bit.Height * bit.Height);  49             int intSplit = 0;  50             intSplit = (int)(7 - (diameter - 200) / 100);  51             if (intSplit < 1)  52                 intSplit = 1;  53             List<PointF> lstPoint = new List<PointF>();  54             for (int i = 0; i < 360; i += intSplit)  55             {  56                 for (int j = (int)diameter / 2; j > 5; j--)  57                 {  58                     Point p = GetPointByAngle(i, j, new PointF(bit.Width / 2, bit.Height / 2));  59                     if (p.X < 0 || p.Y < 0 || p.X >= bit.Width || p.Y >= bit.Height)  60                         continue;  61                     Color _color = bit.GetPixel(p.X, p.Y);  62                     if (!(((int)_color.A) <= alpha || IsLikeColor(_color, transparent)))  63                     {  64                         if (!lstPoint.Contains(p))  65                         {  66                             lstPoint.Add(p);  67                         }  68                         break;  69                     }  70                 }  71             }  72             return lstPoint;  73         }  74   75         /// <summary>  76         /// Determines whether [is like color] [the specified color1].  77         /// </summary>  78         /// <param name="color1">The color1.</param>  79         /// <param name="color2">The color2.</param>  80         /// <returns><c>true</c> if [is like color] [the specified color1]; otherwise, <c>false</c>.</returns>  81         private bool IsLikeColor(Color color1, Color color2)  82         {  83             var cv = Math.Sqrt(Math.Pow((color1.R - color2.R), 2) + Math.Pow((color1.G - color2.G), 2) + Math.Pow((color1.B - color2.B), 2));  84             if (cv <= colorThreshold)  85                 return true;  86             else  87                 return false;  88         }

 1  #region 根据角度得到坐标    English:Get coordinates from angles   2         /// <summary>   3         /// 功能描述:根据角度得到坐标    English:Get coordinates from angles   4         /// 作　　者:HZH   5         /// 创建日期:2019-09-28 11:56:25   6         /// 任务编号:POS   7         /// </summary>   8         /// <param name="angle">angle</param>   9         /// <param name="radius">radius</param>  10         /// <param name="origin">origin</param>  11         /// <returns>返回值</returns>  12         private Point GetPointByAngle(float angle, float radius, PointF origin)  13         {  14             float y = origin.Y + (float)Math.Sin(Math.PI * (angle / 180.00F)) * radius;  15             float x = origin.X + (float)Math.Cos(Math.PI * (angle / 180.00F)) * radius;  16             return new Point((int)x, (int)y);  17         }  18         #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

 1   protected override void OnPaint(PaintEventArgs e)   2         {   3             base.OnPaint(e);   4             e.Graphics.SetGDIHigh();   5    6             this.Region = new System.Drawing.Region(m_borderPath);   7               8             if (_bitCache != null)   9                 e.Graphics.DrawImage(_bitCache, 0, 0);  10              11         }

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

来源：https://www.cnblogs.com/bfyx/p/11603213.html

标签

winform

（七十七）c#Winform自定义控件-采样控件

前提

NuGet

目录

用处及效果

准备工作

开始

最后的话