C#自定义控件—仪表盘

C#用户控件之仪表盘

如何让温度、湿度、压力等有量程的监控值如仪表盘（DashBoard）一样显示？

思路（GDI绘图）：
定义属性：（仪表盘的半径、颜色、间隙；刻度圆的半径、颜色、字体；指针的颜色、占比；文本的字体、占比；）
绘制图形：（半圆、刻度、指针、中心、文本）

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定义属性（将以上属性挨个敲完）

//量程属性（Font、Color、Float、Int、String、Bool）
private float range = 180.0f;
[Browsable(true)]
[Category("布局_G")]
[Description("量程")]
public float Range
{
    get { return range; }

    set
    {
        if (value < 0.0f) return;
        range = value; this.Invalidate();
    }
}

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定义字段

private Graphics g;    //画布
private Pen p;         //笔-绘制线条、曲线
private SolidBrush sb; //笔（填充）-填充矩形、路径
private int width;
private int height;

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仪表盘外环

//画外环的三个圆弧（DrawArc）
float angle = (180.0f - gapAngle * 2) / 3;   //定义角度
RectangleF rec = new RectangleF(10, 10, this.width - 20, this.width - 20);  //定义坐标、宽、高
p = new Pen(colorCircle1, outThickness); 
g.DrawArc(p, rec, -180.0f, angle);  //第一个弧
p = new Pen(colorCircle2, outThickness);
g.DrawArc(p, rec, -180.0f + angle + gapAngle, angle);   //第二个弧
p = new Pen(colorCircle3, outThickness); 
g.DrawArc(p, rec, -180.0f + angle * 2.0f + gapAngle + 2.0f, angle);   //第三个弧

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仪表盘刻度

g.TranslateTransform(this.width * 0.5f, this.width * 0.5f);

点击查看代码

for (int i = 0; i < 4; i++)
{
    float actualAngle = -180.0f + 60.0f * i;
    double x1 = Math.Cos(actualAngle * Math.PI / 180);
    double y1 = Math.Sin(actualAngle * Math.PI / 180);
    float x = Convert.ToSingle(this.width * scaleProportion * 0.5f * x1);
    float y = Convert.ToSingle(this.width * scaleProportion * 0.5f * y1);

    StringFormat sf = new StringFormat();

    if (i > 1)
    {
        x = x - 60;
        sf.Alignment = StringAlignment.Far;
    }
    else
    {
        sf.Alignment = StringAlignment.Near;
    }

    //刻度的坐标，宽，高
    rec = new RectangleF(x, y, 60, 20);
    sb = new SolidBrush(scaleColor);

    if (range % 6 == 0)
    {
        g.DrawString((range / 3 * i).ToString(), scaleFont, sb, rec, sf);
    }
    else
    {
        g.DrawString((range / 3 * i).ToString("f1"), scaleFont, sb, rec, sf);
    }
} 

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仪表盘中心点

//画中心（FillEllipse）
g.FillEllipse(new SolidBrush(pointColor), new RectangleF(-centerRadius, -centerRadius, centerRadius * 2.0f, centerRadius * 2.0f));

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仪表盘指针

//画指针（DrawLine）
p = new Pen(pointColor, 3.0f);  //定义指针颜色、宽度
float sweepAngle = currentValue / range * 180.0f; //划过的角度
float z = this.width * 0.5f * scaleProportion - outThickness * 0.5f - 20.0f;  //指针长度
g.RotateTransform(90.0f); //默认开始角度
g.RotateTransform(sweepAngle);
g.DrawLine(p, new PointF(0, 0), new PointF(0, z));  //画一条线

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下标文本标签

//写文本（DrawString）
g.RotateTransform(-sweepAngle);
g.RotateTransform(-90.0f);  //指定初始角度
StringFormat sf = new StringFormat();
sf.Alignment = StringAlignment.Center;
rec = new RectangleF(this.width * (-0.5f), this.height * textProportion - 0.5f * this.width, this.width, this.height * (1.0f - this.scaleProportion));
string val = TextPrefix + currentValue.ToString() + "" + textUnit ;  //指定字符串
g.DrawString(val, textFont, new SolidBrush(textColor), rec, sf);  

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最后生成（自定义各种监控值显示）

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