C# 實現顏色的梯度漸變案例

 public void DrawRect(gasConcentration[] data)
    {
      Graphics graphic = pictureBox1.CreateGraphics();
      Graphics graphic2 = pictureBox2.CreateGraphics();
      int iCall2 = pictureBox2.Width/10;
           
      data = new gasConcentration[40];
      int iLen = pictureBox1.Width = 540; 
      int iHigh = pictureBox1.Height;
      //初始化十種顏色
      Color[] color = new Color[10] { Color.FromArgb(240, 0, 0), Color.Green, Color.Yellow, Color.Blue, Color.SteelBlue, Color.SeaGreen,
                    Color.Chartreuse, Color.SaddleBrown, Color.Violet, Color.BurlyWood};
          
      //十個顏色，每個顏色三個深度
      for (int i = 0; i < 40; i++)
      {        
        data[i].gasType = i/4 + 1;
        data[i].gasConc = i%4;
      }
      Color c3, c4;
      if (data.Length > 0)
      {       
        int iCall = iLen / data.Length;
        pictureBox2.Width = iCall * data.Length;
        pictureBox1.Width = iCall * data.Length;
        iCall2 = iCall * 4;
        //畫對比框條
        for (int i = 0; i < 10; i++)
        {          
          Brush brush1 = new LinearGradientBrush(new Point(0, iHigh), new Point(iCall2, iHigh), color[i], color[i]);
          graphic2.FillRectangle(brush1, 0 + iCall2 * i, 0, iCall2, iHigh);
          brush1.Dispose();
        }
        //畫顏色條梯度分量
        for (int i = 0; i < data.Length; i++)
        {          
          //將顏色分為三個深度
          if (data[i].gasConc != 0)
            c3 = c4 = Color.FromArgb((byte)(255 * (float)(1 - (data[i].gasConc * 0.01))),
            (byte)(color[data[i].gasType-1].R * (float)(1 - (data[i].gasConc * 0.2))),
            (byte)(color[data[i].gasType-1].G * (float)(1 - (data[i].gasConc * 0.2))),
            (byte)(color[data[i].gasType-1].B * (float)(1 - (data[i].gasConc * 0.2))));
          else
            c3 = c4 = Color.Black;
          Brush brush1 = new LinearGradientBrush(new Point(0, iHigh), new Point(iCall, iHigh), c3, c4);
          graphic.FillRectangle(brush1, 0 + iCall * i , 0, iCall, iHigh);
          brush1.Dispose();                  
        }
      }
      else
      {
        c4 = color[0];
        Brush brush1 = new LinearGradientBrush(new Point(0, iHigh), new Point(iLen, iHigh), c4, c4);        
        graphic.FillRectangle(brush1, 0, 0, iLen, iHigh);
        brush1.Dispose();
      }
      
    }

 public struct gasConcentration
    {
      int iGasType;//氣體名稱
      int iGasConc;//氣體濃度 // 0=no, 1=low, 2=med, 3=high
 
      public int gasType { get { return iGasType; }
        set { iGasType = value; }    }
      public int gasConc { get { return iGasConc; }
        set { iGasConc = value; }
      }
    }

**這是用來獲取某一顏色段的分度集合**
 /// <summary>
    /// 獲得某一顏色區間的顏色集合
    /// </summary>
    /// <param name="sourceColor">起始顏色</param>
    /// <param name="destColor">終止顏色</param>
    /// <param name="count">分度數</param>
    /// <returns>返回顏色集合</returns>
    public static List<Color> GetSingleColorList(Color srcColor, Color desColor, int count)
    {
      List<Color> colorFactorList = new List<Color>();
      int redSpan = desColor.R - srcColor.R;
      int greenSpan = desColor.G - srcColor.G;
      int blueSpan = desColor.B - srcColor.B;
      for (int i = 0; i < count; i++)
      {
        Color color = Color.FromArgb(
          srcColor.R + (int)((double)i / count * redSpan),
          srcColor.G + (int)((double)i / count * greenSpan),
          srcColor.B + (int)((double)i / count * blueSpan)
        );
        colorFactorList.Add(color);
      }
      return colorFactorList;
    }

**這裡就是將紅到紫之間的顏色分為5個區間，利用上面的算法拼接5個區間的分度值，就得到全彩顏色集合**
/// <summary>
    /// 獲取從紅到紫的顏色段的顏色集合
    /// </summary>
    /// <param name="totalCount">分度數</param>
    /// <param name="redToPurple">是否從紅到紫色漸變</param>
    /// <returns>返回顏色集合</returns>
    public static List<Color> GetFullColorList(int totalCount, bool redToPurple = true)
    {
      List<Color> colorList = new List<Color>();
      if (totalCount > 0)
      {
        if (redToPurple)
        {
          colorList.AddRange(GetSingleColorList(Color.Red, Color.Yellow, totalCount / 5 + (totalCount % 5 > 0 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Yellow, Color.Lime, totalCount / 5 + (totalCount % 5 > 1 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Lime, Color.Cyan, totalCount / 5 + (totalCount % 5 > 2 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Cyan, Color.Blue, totalCount / 5 + (totalCount % 5 > 3 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Blue, Color.Magenta, totalCount / 5 + (totalCount % 5 > 4 ? 1 : 0)));
        }
        else
        {
          colorList.AddRange(GetSingleColorList(Color.Magenta, Color.Blue, totalCount / 5 + (totalCount % 5 > 0 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Blue, Color.Cyan, totalCount / 5 + (totalCount % 5 > 1 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Cyan, Color.Lime, totalCount / 5 + (totalCount % 5 > 2 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Lime, Color.Yellow, totalCount / 5 + (totalCount % 5 > 3 ? 1 : 0)));
          colorList.AddRange(GetSingleColorList(Color.Yellow, Color.Red, totalCount / 5 + (totalCount % 5 > 4 ? 1 : 0)));
        }
      }
      return colorList;
    }