C# .Net实现灰度图和HeatMap热力图winform(进阶)

目录

• 一、前文
• 二、渐进颜色调色板
• 三、热力点大小和扩展大小

一、前文

前文可以参考我的前一篇博文：C# .Net实现简易灰度图和酷炫HeatMap热力图winform

但是，先前的热力图效果，我并不满意。不满意的地方主要有三点：

• 热力图的颜色是通过一个调色板图片来实现，如果想要其他颜色，改起来比较麻烦
• 热力图的扩散效果不好看，不够渐进
• 热力图的每个点大小都一致，应该是大小不一才对

因此，我做了改进，上一个图是之前的效果，下一个图是改进后的效果

二、渐进颜色调色板

//创建调色板，颜色映射
private ColorMap[] CreatePalette()
{
    ColorMap[] colorMaps = new ColorMap[256];
    List<Color> newColors = new List<Color>();

    //颜色集合
    newColors.AddRange(GetGradientColorList(Color.Red, Color.Yellow, 64));
    newColors.AddRange(GetGradientColorList(Color.Yellow, Color.Green, 64));
    newColors.AddRange(GetGradientColorList(Color.Green, Color.Blue, 64));
    newColors.AddRange(GetGradientColorList(Color.Blue, Color.Navy, 64));
    //颜色调色板展示
    Bitmap colorBitmap = new Bitmap(colorPanel.Width, colorPanel.Height);

    Graphics graphic = Graphics.FromImage(colorBitmap);
    for (int i = 0; i < 256; i++)
    {
        SolidBrush solidBrush = new SolidBrush(newColors[i]);
        Rectangle rectangle = new Rectangle((int)(i * 2), 0, (int)2, colorPanel.Height);
        graphic.FillRectangle(solidBrush, rectangle);
        graphic.Save();
        solidBrush.Dispose();
    }
    colorPanel.BackgroundImage = colorBitmap;

    // 遍历每个像素并创建一个新的颜色映射
    for (int X = 0; X <= 255; X++)
    {
        colorMaps[X] = new ColorMap();
        colorMaps[X].OldColor = System.Drawing.Color.FromArgb(X, X, X);
        colorMaps[X].NewColor = System.Drawing.Color.FromArgb(255, newColors[X]);
    }
    return colorMaps;
}

/// <summary>
/// 获得两个颜色之间渐进颜色的集合
/// </summary>
/// <param name="sourceColor">起始颜色</param>
/// <param name="destColor">终止颜色</param>
/// <param name="count">渐进颜色的个数</param>
/// <returns>返回颜色集合</returns>
public static List<Color> GetGradientColorList(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;
}

三、热力点大小和扩展大小

private void DrawHeatPoint2(Graphics graphics, HeatPoint heatPoint)
{
    Console.WriteLine("heatPoint.Intensity = " + heatPoint.Intensity);

    int radius = 40 * (heatPoint.Intensity+6) / 240;

    List<System.Drawing.Point> pointsList = new List<System.Drawing.Point>();
    for (double degrees = 0; degrees <= 360; degrees += 10)
    {
        // 在定义半径的圆的圆周上绘制新点
        // 使用点坐标、半径和角度
        // 计算这个迭代点在圆上的位置
        System.Drawing.Point point = new System.Drawing.Point();
        point.X = Convert.ToInt32(heatPoint.X + radius * Math.Cos((Math.PI / 180) * degrees));
        point.Y = Convert.ToInt32(heatPoint.Y + radius * Math.Sin((Math.PI / 180) * degrees));
        pointsList.Add(point);
    }

    // 创建新的颜色混合来告诉 PathGradientBrush 使用什么颜色以及放置它们的位置
    ColorBlend colorBlend = new ColorBlend(3);

    colorBlend.Positions = new float[3] { 0, 0.8f, 1 };
    colorBlend.Colors = new System.Drawing.Color[3]
    {
        System.Drawing.Color.FromArgb(0, System.Drawing.Color.White),
        System.Drawing.Color.FromArgb(heatPoint.Intensity, System.Drawing.Color.Black),
        System.Drawing.Color.FromArgb(heatPoint.Intensity, System.Drawing.Color.Black)
    };

    // 创建新的 PathGradientBrush 以使用圆周点创建径向渐变
    PathGradientBrush brush = new PathGradientBrush(pointsList.ToArray());
    // 将颜色混合传递给 PathGradientBrush 以指示它如何生成渐变
    brush.InterpolationColors = colorBlend;
    graphics.FillPolygon(brush, pointsList.ToArray());
    //brush.Dispose();
}

四、更新视图 

private void UpdateView()
{
    //灰度
    Bitmap bitmap1 = CreateIntensityMask(new Bitmap((int)panel1.Width, (int)panel1.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb), heatPoints, 1);
    panel1.BackgroundImage = bitmap1;

    //上色
    panel3.BackgroundImage = Colorize(bitmap1);
}

private Bitmap CreateIntensityMask(Bitmap bitmap, List<HeatPoint> aHeatPoints)
{
    //从Bitmap获得Graphics GDI+ 绘图图面
    Graphics graphics = Graphics.FromImage(bitmap);
    //清除整个绘图面并以白色填充
    graphics.Clear(System.Drawing.Color.White);
    foreach (HeatPoint point in aHeatPoints)
    {
       DrawHeatPoint2(graphics, point);
    }
    return bitmap;
} 

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