WPF实现强大的动态公式计算

数据库可以定义表不同列之间的计算公式，进行自动公式计算，但如何实现行上的动态公式计算呢？行由于可以动态扩展，在某些应用场景下将能很好的解决实际问题。

1、VS2012新建一个WPF应用程序WpfApp_DynCalc，并添加一个类DynCalc.cs，如下图：

2、编辑MainWindow.xaml，代码如下：

 <Window x:Class="WpfApp_DynCalc.MainWindow"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Title="WPF动态计算示例" Height="350" Width="525">
     <Grid>
         <Grid.Resources>
         <Style TargetType="DataGrid">
             <!--网格线颜色-->
             <Setter Property="CanUserResizeColumns" Value="false"/>
             <Setter Property="Background" Value="#E6DBBB" />
             <Setter Property="BorderBrush" Value="#d6c79b" />
             <Setter Property="HorizontalGridLinesBrush">
                 <Setter.Value>
                     <SolidColorBrush Color="#d6c79b"/>
                 </Setter.Value>
             </Setter>
             <Setter Property="VerticalGridLinesBrush">
                 <Setter.Value>
                     <SolidColorBrush Color="#d6c79b"/>
                 </Setter.Value>
             </Setter>
         </Style>

         <!--标题栏样式-->
         <!--<Style  TargetType="DataGridColumnHeader" >
         <Setter Property="Width" Value="50"/>
         <Setter Property="Height" Value="30"/>
         <Setter Property="FontSize" Value="14" />
         <Setter Property="Background" Value="White" />
         <Setter  Property="FontWeight"  Value="Bold"/>
     </Style>-->

         <Style TargetType="DataGridColumnHeader">
             <Setter Property="SnapsToDevicePixels" Value="True" />
             <Setter Property="MinWidth" Value="0" />
             <Setter Property="MinHeight" Value="28" />
             <Setter Property="Foreground" Value="#323433" />
             <Setter Property="FontSize" Value="14" />
             <Setter Property="Cursor" Value="Hand" />
             <Setter Property="Template">
                 <Setter.Value>
                     <ControlTemplate TargetType="DataGridColumnHeader">
                         <Border x:Name="BackgroundBorder" BorderThickness="0,1,0,1"
                              BorderBrush="#e6dbba"
                               Width="Auto">
                             <Grid >
                                 <Grid.ColumnDefinitions>
                                     <ColumnDefinition Width="*" />
                                 </Grid.ColumnDefinitions>
                                 <ContentPresenter  Margin="0,0,0,0" VerticalAlignment="Center" HorizontalAlignment="Center"/>
                                 <Path x:Name="SortArrow" Visibility="Collapsed" Data="M0,0 L1,0 0.5,1 z" Stretch="Fill"  Grid.Column="2" Width="8" Height="6" Fill="White" Margin="0,0,50,0"
                             VerticalAlignment="Center" RenderTransformOrigin="1,1" />
                                 <Rectangle Width="1" Fill="#d6c79b" HorizontalAlignment="Right" Grid.ColumnSpan="1" />
                                 <!--<TextBlock  Background="Red">
                             <ContentPresenter></ContentPresenter></TextBlock>-->
                             </Grid>
                         </Border>
                     </ControlTemplate>
                 </Setter.Value>
             </Setter>
             <Setter Property="Height" Value="25"/>
         </Style>
         <!--行样式触发-->
         <!--背景色改变必须先设置cellStyle 因为cellStyle会覆盖rowStyle样式-->
         <Style  TargetType="DataGridRow">
             <Setter Property="Background" Value="#F2F2F2" />
             <Setter Property="Height" Value="25"/>
             <Setter Property="Foreground" Value="Black" />
             <Style.Triggers>
                 <!--隔行换色-->
                 <Trigger Property="AlternationIndex" Value="0" >
                     <Setter Property="Background" Value="#e7e7e7" />
                 </Trigger>
                 <Trigger Property="AlternationIndex" Value="1" >
                     <Setter Property="Background" Value="#f2f2f2" />
                 </Trigger>

                 <Trigger Property="IsMouseOver" Value="True">
                     <Setter Property="Background" Value="LightGray"/>
                     <!--<Setter Property="Foreground" Value="White"/>-->
                 </Trigger>

                 <Trigger Property="IsSelected" Value="True">
                     <Setter Property="Foreground" Value="Black"/>
                 </Trigger>
             </Style.Triggers>
         </Style>

         <!--单元格样式触发-->
         <Style TargetType="DataGridCell">
             <Setter Property="Template">
                 <Setter.Value>
                     <ControlTemplate TargetType="DataGridCell">
                         <TextBlock TextAlignment="Center" VerticalAlignment="Center"  >
                            <ContentPresenter />
                         </TextBlock>
                     </ControlTemplate>
                 </Setter.Value>
             </Setter>
             <Style.Triggers>
                 <Trigger Property="IsSelected" Value="True">
                     <!--<Setter Property="Background" Value="White"/>
                 <Setter Property="BorderThickness" Value="0"/>-->
                     <Setter Property="Foreground" Value="Black"/>
                 </Trigger>
             </Style.Triggers>
         </Style>
         </Grid.Resources>

         <DataGrid  Name="dgrid"   HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Height="256" Width="498"  AutoGenerateColumns="False" >
             <DataGrid.Columns>
                 <DataGridTextColumn  Header="指标" Binding="{Binding Zb}" Width="118"/>
                 <DataGridTextColumn  Header="值" Binding="{Binding Value}" Width="100"/>
                 <DataGridTextColumn  Header="公式" Binding="{Binding Formula}" Width="188"/>
             </DataGrid.Columns>
         </DataGrid>
         <Button Content="计 算" HorizontalAlignment="Left" Margin="419,281,0,0" VerticalAlignment="Top" Width="85" Click="Button_Click_1" Height="28" />
         <TextBlock Name="lblResult" HorizontalAlignment="Left" Margin="28,281,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top"/>

     </Grid>
 </Window>

3、编辑后台文件MainWindow.xaml.cs，代码如下：

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
 using System.Windows.Documents;
 using System.Windows.Input;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
 using System.Windows.Navigation;
 using System.Windows.Shapes;

 using System.Collections.ObjectModel;
 namespace WpfApp_DynCalc
 {
     /// <summary>
     /// MainWindow.xaml 的交互逻辑
     /// </summary>
     public partial class MainWindow : Window
     {
         public MainWindow()
         {
             InitializeComponent();

             ObservableCollection<Dynformula> ofs = new ObservableCollection<Dynformula>();
             ofs.Add(new Dynformula { Zb = "A", Value = "", Formula = "" });
             ofs.Add(new Dynformula { Zb = "B", Value = "", Formula = "2*A+1" });
             ofs.Add(new Dynformula { Zb = "C", Value = "", Formula = "B*B" });
             ofs.Add(new Dynformula { Zb = "D", Value = "", Formula = "C-2" });
             ofs.Add(new Dynformula { Zb = "Z", Value = "", Formula = "D+C" });
             this.dgrid.ItemsSource = ofs;

         }

         private void Button_Click_1(object sender, RoutedEventArgs e)
         {
             this.lblResult.Text = "计算...";
              this.dgrid.ItemsSource=   DynCalc.CalcScript(ref this.dgrid);
              this.lblResult.Text = "计算完成!";

         }
     }

     public class Dynformula
     {
         private string zb;

         public string Zb
         {
             get { return zb; }
             set { zb = value; }
         }
         private string value;

         public string Value
         {
             get { return this.value; }
             set { this.value = value; }
         }
         private string formula;

         public string Formula
         {
             get { return formula; }
             set { formula = value; }
         }

     }
 }

3、编辑类DynCalc.cs，代码如下：

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 namespace WpfApp_DynCalc
 {
 using System.Collections.ObjectModel;
 using System.Windows;
 using System.Windows.Controls;
 using System.Reflection;
 using System.Globalization;
 using Microsoft.CSharp;
 using System.CodeDom;
 using System.CodeDom.Compiler;
    public static class DynCalc
     {

        public static ObservableCollection<Dynformula> CalcScript(ref DataGrid dgrid)
        {

            CSharpCodeProvider objCSharpCodePrivoder = new CSharpCodeProvider();
            ICodeCompiler objICodeCompiler = objCSharpCodePrivoder.CreateCompiler();
            CompilerParameters objCompilerParameters = new CompilerParameters();
            objCompilerParameters.ReferencedAssemblies.Add("System.dll");
            objCompilerParameters.GenerateExecutable = false;
            objCompilerParameters.GenerateInMemory = true;
            CompilerResults cr = objICodeCompiler.CompileAssemblyFromSource(objCompilerParameters, GenerateCode(ref dgrid));
            if (cr.Errors.HasErrors)
            {
                Console.WriteLine("编译错误：");
                foreach (CompilerError err in cr.Errors)
                {
                    Console.WriteLine(err.ErrorText);
                }
                return null;
            }
            else
            {
                // 通过反射，调用实例
                Assembly objAssembly = cr.CompiledAssembly;
                object objDynCalc = objAssembly.CreateInstance("DynamicCodeGenerate.RunScript");
                //MethodInfo objMI = objHelloWorld.GetType().GetMethod("OutPut");
                //Console.WriteLine(objMI.Invoke(objHelloWorld, null));

                ObservableCollection<Dynformula> ofsnew = new ObservableCollection<Dynformula>();
                //循环datagrid进行公式计算并赋值
                for (int i = ; i < dgrid.Items.Count; i++)
                {
                    Dynformula item = dgrid.Items[i] as Dynformula;
                    if (item == null)
                    {
                        break;
                    }
                    string zb = item.Zb;
                    PropertyInfo pinfo = objDynCalc.GetType().GetProperty(zb);
                    if (pinfo != null && pinfo.CanRead)                   {
                        //获取属性get值
                        object obj_Name = pinfo.GetValue(objDynCalc, null);
                      //  item.Value = obj_Name.ToString();
                        ofsnew.Add(new Dynformula { Zb = item.Zb, Value = obj_Name.ToString(), Formula = item.Formula});
                    }
                }
                return ofsnew;
            }
        }
        /// <summary>
        /// 计算逻辑C#脚本动态构建
        /// </summary>
        /// <param name="dgrid">存有指标以及指标计算公式的datagrid</param>
        /// <returns>C#脚本</returns>
         static string GenerateCode(ref DataGrid dgrid)
         {
             StringBuilder sb = new StringBuilder();
             StringBuilder sb构建函数内容 = new StringBuilder();
             sb.Append("using System;");
             sb.Append(Environment.NewLine);
             sb.Append("namespace DynamicCodeGenerate");
             sb.Append(Environment.NewLine);
             sb.Append("{");
             sb.Append(Environment.NewLine);
             sb.Append("    public class RunScript");
             sb.Append(Environment.NewLine);
             sb.Append("    {");
             //------------------------------------------------------------
             for(int i=;i<dgrid.Items.Count;i++)
             {
                 Dynformula item = dgrid.Items[i] as Dynformula;
                 if (item == null)
                 {
                     break;
                 }
                 string zb = item.Zb;
                 sb.Append(Environment.NewLine);
                 sb.AppendFormat("        public double _{0};", item.Zb);
                 sb.Append(Environment.NewLine);
                 sb.AppendFormat("        public double {0}",item.Zb);
                 sb.Append(Environment.NewLine);
                 sb.Append("        {");
                 sb.Append(Environment.NewLine);

                 if (item.Formula.Trim() != "")
                 {
                     sb.Append("             set{ "+item.Zb+"=value;}" );
                     sb.Append(Environment.NewLine);
                     sb.Append("             get{return "+ item.Formula + ";}");
                 }
                 else
                 {
                     sb.Append("             set{ _" + item.Zb + "=value;}");
                     sb.Append(Environment.NewLine);
                     sb.Append("             get{return  _"+item.Zb+";} ");
                     sb.Append(Environment.NewLine);
                     sb构建函数内容.Append("       _" + item.Zb + "=" + item.Value);
                 }
                 sb.Append(Environment.NewLine);
                 sb.Append("        }");
                 sb.Append(Environment.NewLine);
             }
             //--------------------------------------------
             //构造函数进行赋值
             sb.Append(Environment.NewLine);
             sb.Append("        public  RunScript()");
             sb.Append(Environment.NewLine);
             sb.Append("        {");
             sb.Append(Environment.NewLine);
             sb.AppendFormat("            {0};",sb构建函数内容.ToString());
             sb.Append(Environment.NewLine);
             sb.Append("        }");
             sb.Append(Environment.NewLine);

             //----------------------------------------------
             sb.Append(Environment.NewLine);
             sb.Append("        public string OutPut()");
             sb.Append(Environment.NewLine);
             sb.Append("        {");
             sb.Append(Environment.NewLine);
             sb.Append("             return \"Hello world!\";");
             sb.Append(Environment.NewLine);
             sb.Append("        }");
             //-----------------------------------------
             sb.Append(Environment.NewLine);
             sb.Append("    }");
             sb.Append(Environment.NewLine);
             sb.Append("}");

             string code = sb.ToString();
             Console.WriteLine(code);
             return code;
         }

     }
 }

4、运行程序，其中值列的值为初始值，点击计算后会根据公式列配置进行动态计算，初始化界面如下:

5、点击计算后界面如下：

可见现在的值是根据公式配置进行动态计算的。当然代码经过扩展还可以支持函数和简单的逻辑判断，如if ...else等。实现更强大的逻辑处理。