WPF利用DrawingContext实现绘制温度计

using System; using System.Windows; using System.Windows.Controls; using System.Windows.Media; namespace WPFDevelopers.Controls {     public class Thermometer : Control     {         public static readonly DependencyProperty MaxValueProperty =             DependencyProperty.Register("MaxValue", typeof(double), typeof(Thermometer), new UIPropertyMetadata(40.0));         public static readonly DependencyProperty MinValueProperty =             DependencyProperty.Register("MinValue", typeof(double), typeof(Thermometer), new UIPropertyMetadata(-10.0));         /// 
         ///     当前值         /// 
         public static readonly DependencyProperty CurrentValueProperty =             DependencyProperty.Register("CurrentValue", typeof(double), typeof(Thermometer),                 new UIPropertyMetadata(OnCurrentValueChanged));         /// 
         ///     步长         /// 
         public static readonly DependencyProperty IntervalProperty =             DependencyProperty.Register("Interval", typeof(double), typeof(Thermometer), new UIPropertyMetadata(10.0));         /// 
         ///     当前值的图形坐标点         /// 
         public static readonly DependencyProperty CurrentGeometryProperty =             DependencyProperty.Register("CurrentGeometry", typeof(Geometry), typeof(Thermometer), new PropertyMetadata(                 Geometry.Parse(@"M 2 132.8                               a 4 4 0 0 1 4 -4                               h 18                               a 4 4 0 0 1 4 4                               v 32.2                               a 4 4 0 0 1 -4 4                               h -18                               a 4 4 0 0 1 -4 -4 z")));         /// 
         ///     构造函数         /// 
         static Thermometer()         {             DefaultStyleKeyProperty.OverrideMetadata(typeof(Thermometer),                 new FrameworkPropertyMetadata(typeof(Thermometer)));         }         public double MaxValue         {             get => (double)GetValue(MaxValueProperty);             set => SetValue(MaxValueProperty, value);         }         public double MinValue         {             get => (double)GetValue(MinValueProperty);             set => SetValue(MinValueProperty, value);         }         public double CurrentValue         {             get => (double)GetValue(CurrentValueProperty);             set             {                 SetValue(CurrentValueProperty, value);                 PaintPath();             }         }         public double Interval         {             get => (double)GetValue(IntervalProperty);             set => SetValue(IntervalProperty, value);         }         public Geometry CurrentGeometry         {             get => (Geometry)GetValue(CurrentGeometryProperty);             set => SetValue(CurrentGeometryProperty, value);         }         private static void OnCurrentValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)         {             var thermometer = d as Thermometer;             thermometer.CurrentValue = Convert.ToDouble(e.NewValue);         }         public override void OnApplyTemplate()         {             base.OnApplyTemplate();             PaintPath();         }         protected override void OnRender(DrawingContext drawingContext)         {             var brush = new SolidColorBrush((Color)ColorConverter.ConvertFromString("#82848A"));             var rect = new Rect();             rect.Width = 30;             rect.Height = 169;             drawingContext.DrawRoundedRectangle(Brushes.Transparent,                 new Pen(brush, 2d),                 rect, 8d, 8d);             #region 华氏温度             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("华",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), textSize: 14D),                 new Point(-49, 115));             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("氏",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), textSize: 14D),                 new Point(-49, 115 + 14));             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("温",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), textSize: 14D),                 new Point(-49, 115 + 28));             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("度",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), textSize: 14D),                 new Point(-49, 115 + 42));             #endregion             #region 摄氏温度             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("摄",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), FlowDirection.LeftToRight,                     14D), new Point(75, 115));             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("氏",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), FlowDirection.LeftToRight,                     14D), new Point(75, 115 + 14));             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("温",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), FlowDirection.LeftToRight,                     14D), new Point(75, 115 + 28));             drawingContext.DrawText(                 DrawingContextHelper.GetFormattedText("度",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), FlowDirection.LeftToRight,                     14D), new Point(75, 115 + 42));             #endregion             #region 画刻度             var total_Value = MaxValue - MinValue;             var cnt = total_Value / Interval;             var one_value = 161d / cnt;             for (var i = 0; i <= cnt; i++)             {                 var formattedText = DrawingContextHelper.GetFormattedText($"{MaxValue - i * Interval}",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), FlowDirection.LeftToRight,                     14D);                 drawingContext.DrawText(formattedText,                     new Point(43, i * one_value - formattedText.Height / 2d)); //减去字体高度的一半                 formattedText = DrawingContextHelper.GetFormattedText($"{(MaxValue - i * Interval) * 1.8d + 32d}",                     (Brush)DrawingContextHelper.BrushConverter.ConvertFromString("#82848A"), textSize: 14D);                 drawingContext.DrawText(formattedText, new Point(-13, i * one_value - formattedText.Height / 2d));                 if (i != 0 && i != 5)                 {                     drawingContext.DrawLine(new Pen(Brushes.Black, 1d),                         new Point(4, i * one_value), new Point(6, i * one_value));                     drawingContext.DrawLine(new Pen(Brushes.Black, 1d),                         new Point(24, i * one_value), new Point(26, i * one_value));                 }             }             #endregion         }         /// 
         ///     动态计算当前值图形坐标点         /// 
         private void PaintPath()         {             var one_value = 161d / ((MaxValue - MinValue) / Interval);             var width = 26d;             var height = 169d - (MaxValue - CurrentValue) * (one_value / Interval);             var x = 2d;             var y = 169d - (169d - (MaxValue - CurrentValue) * (one_value / Interval));             CurrentGeometry = Geometry.Parse($@"M 2 {y + 4}                               a 4 4 0 0 1 4 -4                               h {width - 8}                               a 4 4 0 0 1 4 4                               v {height - 8}                               a 4 4 0 0 1 -4 4                               h -{width - 8}                               a 4 4 0 0 1 -4 -4 z");         }     } }