C#控件开发4—仪表盘

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）

1.定义属性

将以上属性挨个敲完

        private Color colorCircle1 = Color.FromArgb(33, 80, 33);[Browsable(true)][Category("布局_G")][Description("外环颜色1")]public Color ColorCircle1{get { return colorCircle1; }set { colorCircle1 = value; this.Invalidate(); }}private Color colorCircle2 = Color.FromArgb(22, 128, 22);[Browsable(true)][Category("布局_G")][Description("外环颜色2")]public Color ColorCircle2{get { return colorCircle2; }set { colorCircle2 = value; this.Invalidate(); }}private Color colorCircle3 = Color.FromArgb(20, 181, 20);[Browsable(true)][Category("布局_G")][Description("外环颜色3")]public Color ColorCircle3{get { return colorCircle3; }set { colorCircle3 = value; this.Invalidate(); }}private Color pointColor = Color.Green;[Browsable(true)][Category("布局_G")][Description("指针颜色")]public Color PointColor{get { return pointColor; }set { pointColor = value; this.Invalidate(); }}private Color scaleColor = Color.Black;[Browsable(true)][Category("布局_G")][Description("刻度颜色")]public Color ScaleColor{get { return scaleColor; }set { scaleColor = value; this.Invalidate(); }}private float scaleProportion = 0.8f;[Browsable(true)][Category("布局_G")][Description("刻度圆占外圆的比例0-1：越大越紧挨")]public float ScaleProportion{get { return scaleProportion; }set{if (value > 1.0f || value < 0.0f) return;scaleProportion = value; this.Invalidate();}}private Font scaleFont = new Font(new FontFamily("微软雅黑"), 10.0f);[Browsable(true)][Category("布局_G")][Description("字体格式")]public Font ScaleFont{get { return scaleFont; }set{if (value != null){scaleFont = value;this.Invalidate();}}}private string textPrefix = "实际温度：";[Browsable(true)]  //说明：文本关闭[Category("布局_G")][Description("文本前缀")]public string TextPrefix{get { return textPrefix; }set { textPrefix = value; this.Invalidate(); }}private string textUnit = "℃";[Browsable(true)]  //说明：文本关闭[Category("布局_G")][Description("文本单位")]public string TextUnit{get { return textUnit; }set { textUnit = value; this.Invalidate(); }}private Font textFont = new Font("Segoe UI", 10.5f);[Browsable(true)][Category("布局_G")][Description("字体格式")]public Font TextFont{get { return textFont; }set{if (value != null){textFont = value;this.Invalidate();}}}private Color textColor = Color.Black;[Browsable(true)][Category("布局_G")][Description("指针颜色")]public Color TextColor{get { return textColor; }set { textColor = value; this.Invalidate(); }}private float textProportion = 0.88f;[Browsable(true)][Category("布局_G")][Description("文本显示高度占比0-1；越小越靠上")]public float TextProportion{get { return textProportion; }set{if (value > 1.0f || value < 0.0f) return;textProportion = value; this.Invalidate();}}private bool textShow = true;[Browsable(true)][Category("布局_G")][Description("是否显示文本")]public bool TextShow{get { return textShow; }set{textShow = value; this.Invalidate();}}private float currentValue = 100.0f;[Browsable(true)][Category("布局_G")][Description("实时值显示")]public float CurrentValue{get { return currentValue; }set{if (value < 0.0f || value > range) return;currentValue = value; this.Invalidate();}}private int outThickness = 5;[Browsable(true)][Category("布局_G")][Description("外环画笔的宽度")]public int OutThickness{get { return outThickness; }set{if (value <= 0) return;outThickness = value; this.Invalidate();}}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();}}private float centerRadius = 6.0f;[Browsable(true)][Category("布局_G")][Description("中心半径")]public float CenterRadius{get { return centerRadius; }set{if (value <= 0.0f) return;centerRadius = value; this.Invalidate();}}private float gapAngle = 2.0f;[Browsable(true)][Category("布局_G")][Description("间隙角度")]public float GapAngle{get { return gapAngle; }set{if (value <= 0.0f) return;gapAngle = value; this.Invalidate();}}#endregion

2.绘制图形

定义画布、笔
画布质量
画外环-定义角度、坐标、宽度、高度
画内圆
画指针
文本标签

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;

 #region 重绘【画外圆、画刻度、画指针、画中心、画文本】protected override void OnPaint(PaintEventArgs e){base.OnPaint(e);//画布质量g = e.Graphics;g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;this.width = this.Width;this.height = this.Height;//特殊情况处理if (this.width <= 20 || this.height <= 20) return;if (this.height < this.width * 0.5f) return;// 画外环-定义角度、坐标、宽度、高度float angle = (180.0f - gapAngle * 2) / 3;RectangleF rec = new RectangleF(10, 10, this.width - 20, this.width - 20);//第一个圆弧p = new Pen(colorCircle3, outThickness);g.DrawArc(p, rec, -180.0f, angle);//第二个圆弧p = new Pen(colorCircle2, outThickness);g.DrawArc(p, rec, -180.0f + angle + gapAngle, angle);//第三个圆弧p = new Pen(colorCircle1, outThickness);g.DrawArc(p, rec, -180.0f + angle * 2.0f + gapAngle + 2.0f, angle);//画刻度g.TranslateTransform(this.width * 0.5f, this.width * 0.5f);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);}}//画内圆g.FillEllipse(new SolidBrush(pointColor), new RectangleF(-centerRadius, -centerRadius, centerRadius * 2.0f, centerRadius * 2.0f));//画指针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);//画线g.DrawLine(p, new PointF(0, 0), new PointF(0, z));//文本标签if (textShow){g.RotateTransform(-sweepAngle);g.RotateTransform(-90.0f);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 + "（" + (currentValue / range * 100.0f).ToString("f0") + "%" + "）";string val = TextPrefix + currentValue.ToString() + "" + textUnit ;//文本g.DrawString(val, textFont, new SolidBrush(textColor), rec, sf);}}#endregion