C# .Net实现灰度图和HeatMap热力图winform(进阶)

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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