I usually set all the static parameters of my application in one static or singleton class, called something common, for example ApplicationSettings (or MainWindowSettings , if the values are used only by MainWindow )
If the values are for customization, they are included in app.config and loaded into the constructor of the static class. If not, I will just copy them in my static class so that they are easy to find / modify later.
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; } }
For calculated values in your XAML, I usually use the MathConverter , which I wrote, which allows me to write a binding with a mathematical expression and pass its used values.
The version that I posted on my blog is just an IValueConverter , but it’s pretty easy to deploy it to IMultiValueConverter so that it can take several related values.
<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>
Normally, I would hide all this messy XAML in style somewhere, so it does not clutter up my main XAML code and just apply the style where necessary.
Here is a copy of the converter code that I use for 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; } }
But honestly, if these values are used in only one form, I just set the values in the Loaded event in the code behind the View :)