只读值的优雅解决方案

Question

我正在开发一个WPF应用程序，其窗口大小和组件位置必须在初始化时动态计算，因为它们基于我使用的主UserControl大小和一些其他次要大小设置。因此，就目前而言，我已经放在那些常量值在我的窗口代码如下：

public const Double MarginInner = 6D; 
public const Double MarginOuter = 10D; 
public const Double StrokeThickness = 3D; 

public static readonly Double TableHeight = (StrokeThickness * 2D) + (MarginInner * 3D) + (MyUC.RealHeight * 2.5D); 
public static readonly Double TableLeft = (MarginOuter * 3D) + MyUC.RealHeight + MarginInner; 
public static readonly Double TableTop = MarginOuter + MyUC.RealHeight + MarginInner; 
public static readonly Double TableWidth = (StrokeThickness * 2D) + (MyUC.RealWidth * 6D) + (MarginInner * 7D); 
public static readonly Double LayoutHeight = (TableTop * 2D) + TableHeight; 
public static readonly Double LayoutWidth = TableLeft + TableWidth + MarginOuter; 

然后，我只是用他们我的XAML里面如下：

<Window x:Class="MyNS.MainWindow" ResizeMode="NoResize" SizeToContent="WidthAndHeight"> 
    <Canvas x:Name="m_Layout" Height="{x:Static ns:MainWindow.LayoutHeight}" Width="{x:Static ns:MainWindow.LayoutWidth}"> 

嗯...无话可说。它的工作原理...但它是如此丑陋看到，我想知道是否有任何更好的解决方案。我不知道......也许是一个设置文件，绑定，内联XAML计算或其他任何东西......这会使它看起来更好。

Answer 1

我通常把所有的静态我的应用程序设置中称为东西通用的单一静态或单例类，像ApplicationSettings

（或MainWindowSettings如果值仅由MainWindow使用）如果值是指用户可配置的，他们进入app.config并加载到静态类的构造函数中。如果没有，我只是在我的静态类中对它们进行硬编码，以便以后很容易找到/更改。

public static class ApplicationSettings 
{ 
    public static Double MarginInner { get; private set; } 
    public static Double MarginOuter { get; private set; } 
    public static Double StrokeThickness { get; private set; } 

    static ApplicationSettings() 
    { 
     MarginInner = 6D; 
     MarginOuter = 10D; 
     StrokeThickness = 3D; 
    } 
} 

对于您的XAML计算值，我通常使用一个MathConverter我写的，让我写一个数学表达式的绑定，并通过它的值来使用。

我发布在我的博客上的版本只是IValueConverter，但它很容易展开为IMultiValueConverter，因此它可以接受多个绑定值。

<Setter Property="Height"> 
    <Setter.Value> 
     <MultiBinding Converter="{StaticResource MathMultiConverter}" 
        ConverterParameter="(@VALUE1 * 2D) + (@VALUE2 * 3D) + (@VALUE3 * 2.5D)"> 
     <Binding RelativeSource="{x:Static ns:ApplicationSettings.StrokeThickness }" /> 
     <Binding RelativeSource="{x:Static ns:ApplicationSettings.MarginInner}" /> 
     <Binding ElementName="MyUc" Path="ActualHeight" /> 
     </MultiBinding> 
    </Setter.Value> 
</Setter> 

通常我会躲在一个风格这一切混乱的XAML的地方，因此它不会弄乱我的主要XAML代码，只是应用在需要的地方风格。

这是我使用的转换代码的副本IMultiValueConvter

// Does a math equation on a series of bound values. 
// Use @VALUEN in your mathEquation as a substitute for bound values, where N is the 0-based index of the bound value 
// Operator order is parenthesis first, then Left-To-Right (no operator precedence) 
public class MathMultiConverter : IMultiValueConverter 
{ 
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) 
    { 
     // Remove spaces 
     var mathEquation = parameter as string; 
     mathEquation = mathEquation.Replace(" ", ""); 

     // Loop through values to substitute placeholders for values 
     // Using a backwards loop to avoid replacing something like @VALUE10 with @VALUE1 
     for (var i = (values.Length - 1); i >= 0; i--) 
      mathEquation = mathEquation.Replace(string.Format("@VALUE{0}", i), values[i].ToString()); 

     // Return result of equation 
     return MathConverterHelpers.RunEquation(ref mathEquation); 
    } 

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) 
    { 
     throw new NotImplementedException(); 
    } 
} 

public static class MathConverterHelpers 
{ 
    private static readonly char[] _allOperators = new[] { '+', '-', '*', '/', '%', '(', ')' }; 

    private static readonly List<string> _grouping = new List<string> { "(", ")" }; 
    private static readonly List<string> _operators = new List<string> { "+", "-", "*", "/", "%" }; 


    public static double RunEquation(ref string mathEquation) 
    { 
     // Validate values and get list of numbers in equation 
     var numbers = new List<double>(); 
     double tmp; 

     foreach (string s in mathEquation.Split(_allOperators)) 
     { 
      if (s != string.Empty) 
      { 
       if (double.TryParse(s, out tmp)) 
       { 
        numbers.Add(tmp); 
       } 
       else 
       { 
        // Handle Error - Some non-numeric, operator, or grouping character found in string 
        throw new InvalidCastException(); 
       } 
      } 
     } 

     // Begin parsing method 
     EvaluateMathString(ref mathEquation, ref numbers, 0); 

     // After parsing the numbers list should only have one value - the total 
     return numbers[0]; 
    } 

    // Evaluates a mathematical string and keeps track of the results in a List<double> of numbers 
    private static void EvaluateMathString(ref string mathEquation, ref List<double> numbers, int index) 
    { 
     // Loop through each mathemtaical token in the equation 
     string token = GetNextToken(mathEquation); 

     while (token != string.Empty) 
     { 
      // Remove token from mathEquation 
      mathEquation = mathEquation.Remove(0, token.Length); 

      // If token is a grouping character, it affects program flow 
      if (_grouping.Contains(token)) 
      { 
       switch (token) 
       { 
        case "(": 
         EvaluateMathString(ref mathEquation, ref numbers, index); 
         break; 

        case ")": 
         return; 
       } 
      } 

      // If token is an operator, do requested operation 
      if (_operators.Contains(token)) 
      { 
       // If next token after operator is a parenthesis, call method recursively 
       string nextToken = GetNextToken(mathEquation); 
       if (nextToken == "(") 
       { 
        EvaluateMathString(ref mathEquation, ref numbers, index + 1); 
       } 

       // Verify that enough numbers exist in the List<double> to complete the operation 
       // and that the next token is either the number expected, or it was a (meaning 
       // that this was called recursively and that the number changed 
       if (numbers.Count > (index + 1) && 
        (double.Parse(nextToken) == numbers[index + 1] || nextToken == "(")) 
       { 
        switch (token) 
        { 
         case "+": 
          numbers[index] = numbers[index] + numbers[index + 1]; 
          break; 
         case "-": 
          numbers[index] = numbers[index] - numbers[index + 1]; 
          break; 
         case "*": 
          numbers[index] = numbers[index] * numbers[index + 1]; 
          break; 
         case "/": 
          numbers[index] = numbers[index]/numbers[index + 1]; 
          break; 
         case "%": 
          numbers[index] = numbers[index] % numbers[index + 1]; 
          break; 
        } 
        numbers.RemoveAt(index + 1); 
       } 
       else 
       { 
        // Handle Error - Next token is not the expected number 
        throw new FormatException("Next token is not the expected number"); 
       } 
      } 

      token = GetNextToken(mathEquation); 
     } 
    } 

    // Gets the next mathematical token in the equation 
    private static string GetNextToken(string mathEquation) 
    { 
     // If we're at the end of the equation, return string.empty 
     if (mathEquation == string.Empty) 
     { 
      return string.Empty; 
     } 

     // Get next operator or numeric value in equation and return it 
     string tmp = ""; 
     foreach (char c in mathEquation) 
     { 
      if (_allOperators.Contains(c)) 
      { 
       return (tmp == "" ? c.ToString() : tmp); 
      } 
      else 
      { 
       tmp += c; 
      } 
     } 

     return tmp; 
    } 
} 

但坦白地说，如果这些值都在一个单一的形式，那么我刚才设置的值在Loaded事件仅用于代码背后的观点:)

Answer 2

把那些静态的放在app.config中，它们在那里会更干净。

使用app.config，您首先必须参考System.Configuration。

然后你就可以做（有可能是某种类型的铸造涉及）：

ConfigurationManager.AppSettings["MarginInner"]; 

要检索：

<configuration> 
    <appsettings> 
     <add key="MarginInner" value="6D" /> 
    </appsettings> 
</configuration> 

那么也许有一个静态类来保存动态计算，东西如：

public class CalculationHelper 
{ 
    //your dynamic properties in here 
} 

Answer 3

mattytommo的回答只处理您拥有的常量值（页边距和笔划厚度），但不包含计算的字段。

我会在什么马蒂说一起选择，添加从app.config文件中检索恒值的设置类，也做相应的计算需要，然后我可以在XAML

引用相应的属性

即

{ Settings.MainWindow.LayoutWidth } 

编辑：

它看起来像马蒂有相同的，虽然他我之间张贴在编辑;）