WPF 实现温度计

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  在WPF中没有现成的温度计控件，所以我们自己实现一个。

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01

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代码如下

一、创建 Thermometer.cs 继承 Control代码如下。

using System;
using System.Globalization;
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 double MaxValue
        
            get  return (double)GetValue(MaxValueProperty); 


            set  SetValue(MaxValueProperty, value); 
        


        public static readonly DependencyProperty MinValueProperty = 
            DependencyProperty.Register("MinValue", typeof(double), typeof(Thermometer), new UIPropertyMetadata(-10.0));


        public double MinValue
        
            get  return (double)GetValue(MinValueProperty); 


            set  SetValue(MinValueProperty, value); 
        


        /// <summary>
        /// 当前值
        /// </summary>
        public static readonly DependencyProperty CurrentValueProperty = 
            DependencyProperty.Register("CurrentValue", typeof(double), typeof(Thermometer), new UIPropertyMetadata(OnCurrentValueChanged));


        private static void OnCurrentValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        
            Thermometer thermometer = d as Thermometer;
            thermometer.CurrentValue = Convert.ToDouble(e.NewValue);
        


        public double CurrentValue
        
            get  return (double)GetValue(CurrentValueProperty); 


            set
            
                SetValue(CurrentValueProperty, value);


                PaintPath();
            
        


        /// <summary>
        /// 步长
        /// </summary>
        public static readonly DependencyProperty IntervalProperty = 
            DependencyProperty.Register("Interval", typeof(double), typeof(Thermometer), new UIPropertyMetadata(10.0));


        public double Interval
        
            get  return (double)GetValue(IntervalProperty); 


            set  SetValue(IntervalProperty, value); 
        


        /// <summary>
        /// 当前值的图形坐标点
        /// </summary>
        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")));


        public Geometry CurrentGeometry
        
            get  return (Geometry)GetValue(CurrentGeometryProperty); 


            set  SetValue(CurrentGeometryProperty, value); 
        


        /// <summary>
        /// 构造函数
        /// </summary>
        static Thermometer()
        
            DefaultStyleKeyProperty.OverrideMetadata(typeof(Thermometer), new FrameworkPropertyMetadata(typeof(Thermometer)));
        


        public override void OnApplyTemplate()
        
            base.OnApplyTemplate();


            PaintPath();
        


        protected override void OnRender(DrawingContext drawingContext)
        
            SolidColorBrush brush = new SolidColorBrush((Color)ColorConverter.ConvertFromString("#82848A"));
            Rect 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(GetFormattedText("华"), new Point(-49, 115));




            drawingContext.DrawText(GetFormattedText("氏"), new Point(-49, 115 + 14));




            drawingContext.DrawText(GetFormattedText("温"), new Point(-49, 115 + 28));




            drawingContext.DrawText(GetFormattedText("度"), new Point(-49, 115 + 42));


            #endregion


            #region 摄氏温度




            drawingContext.DrawText(GetFormattedText("摄", FlowDirection.LeftToRight), new Point(75, 115));




            drawingContext.DrawText(GetFormattedText("氏", FlowDirection.LeftToRight), new Point(75, 115 + 14));




            drawingContext.DrawText(GetFormattedText("温", FlowDirection.LeftToRight), new Point(75, 115 + 28));




            drawingContext.DrawText(GetFormattedText("度", FlowDirection.LeftToRight), 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 (int i = 0; i <= cnt; i++)
            
                var formattedText = GetFormattedText($"MaxValue - (i * Interval)", FlowDirection.LeftToRight);


                drawingContext.DrawText(formattedText, new Point(43, i * one_value - (formattedText.Height / 2d)));//减去字体高度的一半


                formattedText = GetFormattedText($"(MaxValue - (i * Interval)) * 1.8d + 32d");


                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
        


        private FormattedText GetFormattedText(string text, FlowDirection flowDirection = FlowDirection.RightToLeft)
        
            return new FormattedText(text,
               CultureInfo.CurrentUICulture,
               flowDirection,
               new Typeface("Microsoft YaHei"),
               14d,
               new SolidColorBrush((Color)ColorConverter.ConvertFromString("#82848A")));
        


        /// <summary>
        /// 动态计算当前值图形坐标点
        /// </summary>
        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");

二、创建ThermometerExample.xaml代码如下

<UserControl x:Class="WPFDevelopers.Samples.ExampleViews.ThermometerExample"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:wpfdev="https://github.com/yanjinhuagood/WPFDevelopers"
             xmlns:local="clr-namespace:WPFDevelopers.Samples.ExampleViews"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <Grid>
        
        <Border Background="White" 
                CornerRadius="12"
                Width="400" Height="400"
                Effect="StaticResource NormalShadowDepth">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition/>
                    <ColumnDefinition/>
                </Grid.ColumnDefinitions>
                <Slider x:Name="PART_Slider" IsSnapToTickEnabled="True"
                Value="10"
                Minimum="-10"
                Maximum="40" 
                Orientation="Vertical"
                Height="300"/>
                <Grid VerticalAlignment="Center"
                      Margin="160,0,0,0">
                    <Path Fill="StaticResource PrimaryMouseOverSolidColorBrush" 
                          Stroke="StaticResource PrimaryMouseOverSolidColorBrush"
                          StrokeThickness="1" Opacity=".6"
                          Data="Binding ElementName=PART_Thermometer, Path=CurrentGeometry,Mode=TwoWay"/>
                    <wpfdev:Thermometer x:Name="PART_Thermometer"
                                        CurrentValue="Binding ElementName=PART_Slider,Path=Value,Mode=TwoWay"/>
                </Grid>
                <TextBlock Text="Binding ElementName=PART_Thermometer,Path=CurrentValue,StringFormat=0℃" 
                           FontSize="24" Grid.Column="1"
                           Foreground="StaticResource PrimaryPressedSolidColorBrush" FontFamily="Bahnschrift"
                           HorizontalAlignment="Center" VerticalAlignment="Center"/>
            </Grid>
        </Border>
    </Grid>
</UserControl>

02

—

效果预览

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源码地址如下

github：https://github.com/yanjinhuagood/WPFDevelopers.git

gitee：https://gitee.com/yanjinhua/WPFDevelopers.git

WPF开发者QQ群： 340500857 

blogs： https://www.cnblogs.com/yanjinhua

Github：https://github.com/yanjinhuagood

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