Merge pull request #4 from djengineerllc/patch-3

Add converter for show/hide if there is text

Author: djengineerllc

MahApps.Metro/Converters/StringToVisibilityConverter.cs

@@ -0,0 +1,87 @@
+//	--------------------------------------------------------------------
+//		Obtained from: WPFSmartLibrary
+//		For more information see : http://wpfsmartlibrary.codeplex.com/
+//		(by DotNetMastermind)
+//	--------------------------------------------------------------------
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Windows;
+using System.Windows.Data;
+using System.Windows.Markup;
+
+namespace MahApps.Metro.Converters
+{
+    /// <summary>
+    /// Converts a String into a Visibility enumeration (and back)
+    /// The FalseEquivalent can be declared with the "FalseEquivalent" property
+    /// </summary>
+    [ValueConversion(typeof(string), typeof(Visibility))]
+    [MarkupExtensionReturnType(typeof(StringToVisibilityConverter))]
+    public class StringToVisibilityConverter : MarkupExtension, IValueConverter
+    {
+        /// <summary>
+        /// FalseEquivalent (default : Visibility.Collapsed => see Constructor)
+        /// </summary>
+        public Visibility FalseEquivalent { get; set; }
+
+        /// <summary>
+        /// Define whether the opposite boolean value is crucial (default : false)
+        /// </summary>
+        public bool OppositeStringValue { get; set; }
+
+        /// <summary>
+        /// Initialize the properties with standard values
+        /// </summary>
+        public StringToVisibilityConverter()
+        {
+            this.FalseEquivalent = Visibility.Collapsed;
+            this.OppositeStringValue = false;
+        }
+
+        #region IValueConverter Members
+
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is string && targetType == typeof(Visibility))
+            {
+                if (this.OppositeStringValue == true)
+                {
+                    return ((value as string).ToLower().Equals(String.Empty)) ? Visibility.Visible : this.FalseEquivalent;
+                }
+                return ((value as string).ToLower().Equals(String.Empty)) ? this.FalseEquivalent : Visibility.Visible;
+            }
+            return value;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is Visibility)
+            {
+                if (this.OppositeStringValue == true)
+                {
+                    return ((Visibility)value == Visibility.Visible) ? String.Empty : "visible";
+                }
+                return ((Visibility)value == Visibility.Visible) ? "visible" : String.Empty;
+            }
+            return value;
+        }
+
+        #endregion
+
+        #region MarkupExtension "overrides"
+
+        public override object ProvideValue(IServiceProvider serviceProvider)
+        {
+            return new StringToVisibilityConverter
+            {
+                FalseEquivalent = this.FalseEquivalent,
+                OppositeStringValue = this.OppositeStringValue
+            };
+        }
+
+        #endregion
+    }
+}