Feature/auto watermark

src/MahApps.Metro.Samples/MahApps.Metro.Demo/MahApps.Metro.Demo.Shared/ExampleViews/DateExamples.xaml.cs

@@ -2,6 +2,9 @@
 
 namespace MetroDemo.ExampleViews
 {
+    using System.Windows;
+    using MahApps.Metro.Controls;
+
     /// <summary>
     /// Interaction logic for DateExamples.xaml
     /// </summary>
@@ -10,6 +13,10 @@ public partial class DateExamples : UserControl
         public DateExamples()
         {
             InitializeComponent();
+#if NET4_5
+            this.AutoWatermark.Visibility = Visibility.Visible;
+            this.AutoWatermark.SetValue(TextBoxHelper.AutoWatermarkProperty, true);
+#endif
         }
     }
 }

src/MahApps.Metro.Samples/MahApps.Metro.Demo/MahApps.Metro.Demo.Shared/MainWindowViewModel.cs

@@ -16,6 +16,9 @@
 using MetroDemo.ExampleViews;
 using NHotkey;
 using NHotkey.Wpf;
+#if NET4_5
+    using MahApps.Metro.Controls.Helper;
+#endif
 
 namespace MetroDemo
 {
@@ -125,6 +128,10 @@ public int? IntegerGreater10Property
         }
 
         DateTime? _datePickerDate;
+
+#if NET4_5
+        [Watermark("Auto resolved Watermark")]
+#endif
         public DateTime? DatePickerDate
         {
             get { return this._datePickerDate; }
@@ -254,6 +261,7 @@ public string this[string columnName]
             }
         }
 
+        [Description("Test-Property")]
         public string Error { get { return string.Empty; } }
 
         private ICommand singleCloseTabCommand;

src/MahApps.Metro/MahApps.Metro.Shared/Controls/Helper/TextBoxHelper.cs

@@ -6,10 +6,15 @@
 using System.Windows.Documents;
 using System.Windows.Input;
 using System.Windows.Media;
+using System.ComponentModel;
+#if NET4_5
+using System.Collections.Generic;
+using System.Reflection;
+using MahApps.Metro.Controls.Helper;
+#endif
 
 namespace MahApps.Metro.Controls
 {
-    using System.ComponentModel;
 
     /// <summary>
     /// A helper class that provides various attached properties for the TextBox control.
@@ -50,6 +55,20 @@ public class TextBoxHelper
 
         public static readonly DependencyProperty IsSpellCheckContextMenuEnabledProperty = DependencyProperty.RegisterAttached("IsSpellCheckContextMenuEnabled", typeof(bool), typeof(TextBoxHelper), new FrameworkPropertyMetadata(false, UseSpellCheckContextMenuChanged));
 
+#if NET4_5
+        public static readonly DependencyProperty AutoWatermarkProperty = DependencyProperty.RegisterAttached("AutoWatermark", typeof(bool), typeof(TextBoxHelper), new PropertyMetadata(default(bool), OnAutoWatermarkChanged));
+
+        private static readonly Dictionary<Type, DependencyProperty> AutoWatermarkPropertyMapping = new Dictionary<Type, DependencyProperty>
+                                                                                                    {
+                                                                                                        { typeof(TextBox), TextBox.TextProperty },
+                                                                                                        { typeof(ComboBox), Selector.SelectedItemProperty },
+                                                                                                        { typeof(NumericUpDown), NumericUpDown.ValueProperty },
+                                                                                                        { typeof(DatePicker), DatePicker.SelectedDateProperty },
+                                                                                                        { typeof(TimePicker), TimePickerBase.SelectedTimeProperty },
+                                                                                                        { typeof(DateTimePicker), DateTimePicker.SelectedDateProperty }
+                                                                                                    };
+#endif
+
         /// <summary>
         /// Indicates if a TextBox or RichTextBox should use SpellCheck context menu
         /// </summary>
@@ -66,6 +85,61 @@ public static void SetIsSpellCheckContextMenuEnabled(UIElement element, bool val
             element.SetValue(IsSpellCheckContextMenuEnabledProperty, value);
         }
 
+#if NET4_5
+        [Category(AppName.MahApps)]
+        [AttachedPropertyBrowsableForType(typeof(TextBox))]
+        [AttachedPropertyBrowsableForType(typeof(ComboBox))]
+        [AttachedPropertyBrowsableForType(typeof(DatePicker))]
+        [AttachedPropertyBrowsableForType(typeof(TimePickerBase))]
+        [AttachedPropertyBrowsableForType(typeof(NumericUpDown))]
+        public static bool GetAutoWatermark(DependencyObject element)
+        {
+            return (bool)element.GetValue(AutoWatermarkProperty);
+        }
+
+        public static void SetAutoWatermark(DependencyObject element, bool value)
+        {
+            element.SetValue(AutoWatermarkProperty, value);
+        }
+
+        private static void OnAutoWatermarkChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            FrameworkElement element = d as FrameworkElement;
+            if (element != null)
+            {
+                element.Loaded += OnControlWithAutoWatermarkSupportLoaded;
+            }
+        }
+
+        private static void OnControlWithAutoWatermarkSupportLoaded(object o, RoutedEventArgs routedEventArgs)
+        {
+            FrameworkElement obj = (FrameworkElement)o;
+            obj.Loaded -= OnControlWithAutoWatermarkSupportLoaded;
+
+            DependencyProperty dependencyProperty;
+
+            if (!AutoWatermarkPropertyMapping.TryGetValue(obj.GetType(), out dependencyProperty))
+            {
+                throw new NotSupportedException($"{nameof(AutoWatermarkProperty)} is not supported for {obj.GetType()}");
+            }
+            var binding = obj.GetBindingExpression(dependencyProperty);
+
+            if (binding != null)
+            {
+                var dataItem = binding.DataItem.GetType();
+                var property = dataItem.GetProperty(binding.ResolvedSourcePropertyName, BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance);
+                if (property != null)
+                {
+                    var attribute = property.GetCustomAttribute<WatermarkAttribute>();
+                    if (attribute != null)
+                    {
+                        obj.SetValue(WatermarkProperty, attribute.Caption);
+                    }
+                }
+            }
+        }
+#endif
+
         private static void UseSpellCheckContextMenuChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
         {
             var tb = d as TextBoxBase;
@@ -212,7 +286,7 @@ public static void SetUseFloatingWatermark(DependencyObject obj, bool value)
         {
             obj.SetValue(UseFloatingWatermarkProperty, value);
         }
-
+        
         /// <summary>
         /// Gets if the attached TextBox has text.
         /// </summary>
@@ -310,15 +384,15 @@ private static void OnIsMonitoringChanged(DependencyObject d, DependencyProperty
                 }
             }
         }
-
+        
         private static void SetTextLength<TDependencyObject>(TDependencyObject sender, Func<TDependencyObject, int> funcTextLength) where TDependencyObject : DependencyObject
         {
             if (sender != null)
             {
                 var value = funcTextLength(sender);
                 sender.SetValue(TextLengthProperty, value);
                 sender.SetValue(HasTextProperty, value >= 1);
-        }
+            }
         }
 
         private static void TextChanged(object sender, RoutedEventArgs e)

src/MahApps.Metro/MahApps.Metro.Shared/Controls/Helper/WatermarkAttribute.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace MahApps.Metro.Controls.Helper
+{
+#if NET4_5
+    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
+    public class WatermarkAttribute : Attribute
+    {
+        public WatermarkAttribute(string caption)
+        {
+            this.Caption = caption;
+        }
+
+        public string Caption { get; set; }
+    }
+#endif
+}

src/MahApps.Metro/MahApps.Metro.Shared/MahApps.Metro.Shared.projitems

@@ -77,6 +77,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Helper\TextBoxHelper.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Helper\ToggleButtonHelper.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Helper\VisibilityHelper.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Controls\Helper\WatermarkAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\HotKeyBox.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\IMetroThumb.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\LayoutInvalidationCatcher.cs" />