[WPF系列]-高级部分 Shadowed TextBox

Download Solution

ShadowedTextBoxExample.zip (70.3 KB)

Usage

<local:ShadowedTextBox Label="First Name" Text="{Binding FirstName}" />

Styles

<Style x:Key="shadowedLabelStyle">

    <Setter Property="TextBlock.Foreground" Value="{x:Static SystemColors.ControlDarkBrush}" />

    <Setter Property="FrameworkElement.Opacity" Value="0.8" />

    <Setter Property="TextBlock.FontSize" Value="12" />

    <Setter Property="TextBlock.FontStyle" Value="Italic" />

    <Setter Property="TextBlock.Margin" Value="8,4,4,4" />

</Style>



<Style TargetType="{x:Type local:ShadowedTextBox}">

    <Setter Property="FontSize" Value="14" />

    <Setter Property="Margin" Value="5,2,2,2" />

    <Setter Property="LabelStyle" Value="{StaticResource shadowedLabelStyle}" />

</Style>

ShadowedTextBox.cs

using System.ComponentModel;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;



namespace ShadowedTextBoxExample

{

    public class ShadowedTextBox : TextBox

    {

        #region Properties

        public string Label

        {

            get { return (string)GetValue(LabelProperty); }

            set { SetValue(LabelProperty, value); }

        }



        // Using a DependencyProperty as the backing store for Label.  This enables animation, styling, binding, etc...

        public static readonly DependencyProperty LabelProperty =

            DependencyProperty.Register("Label", typeof(string), typeof(ShadowedTextBox), new UIPropertyMetadata("Label"));



        public Style LabelStyle

        {

            get { return (Style)GetValue(LabelStyleProperty); }

            set { SetValue(LabelStyleProperty, value); }

        }



        // Using a DependencyProperty as the backing store for LabelStyle.  This enables animation, styling, binding, etc...

        public static readonly DependencyProperty LabelStyleProperty =

            DependencyProperty.Register("LabelStyle", typeof(Style), typeof(ShadowedTextBox), new UIPropertyMetadata(null));





        public bool HasText

        {

            get { return (bool)GetValue(HasTextProperty); }

            private set { SetValue(HasTextPropertyKey, value); }

        }



        private static readonly DependencyPropertyKey HasTextPropertyKey =

            DependencyProperty.RegisterReadOnly("HasText", typeof(bool), typeof(ShadowedTextBox), new PropertyMetadata(false));

        public static readonly DependencyProperty HasTextProperty = HasTextPropertyKey.DependencyProperty;



        #endregion



        public ShadowedTextBox()

            : base()

        {

        }



        AdornerLayer myAdornerLayer;

        AdornerLabel myAdornerLabel;

        public override void OnApplyTemplate()

        {

            base.OnApplyTemplate();



            myAdornerLayer = AdornerLayer.GetAdornerLayer(this);

            myAdornerLabel = new AdornerLabel(this, this.Label, this.LabelStyle);

            UpdateAdorner(this);



            DependencyPropertyDescriptor focusProp = DependencyPropertyDescriptor.FromProperty(FrameworkElement.IsFocusedProperty, typeof(FrameworkElement));

            if (focusProp != null)

            {

                focusProp.AddValueChanged(this, delegate

                {

                    UpdateAdorner(this);

                });

            }



            DependencyPropertyDescriptor containsTextProp = DependencyPropertyDescriptor.FromProperty(ShadowedTextBox.HasTextProperty, typeof(ShadowedTextBox));

            if (containsTextProp != null)

            {

                containsTextProp.AddValueChanged(this, delegate

                {

                    UpdateAdorner(this);

                });

            }

        }



        protected override void OnTextChanged(TextChangedEventArgs e)

        {

            HasText = this.Text != "";



            base.OnTextChanged(e);

        }



        protected override void OnDragEnter(DragEventArgs e)

        {

            myAdornerLayer.RemoveAdorners<AdornerLabel>(this); // requires AdornerExtensions.cs



            base.OnDragEnter(e);

        }



        protected override void OnDragLeave(DragEventArgs e)

        {

            UpdateAdorner(this);



            base.OnDragLeave(e);

        }



        private void UpdateAdorner(FrameworkElement elem)

        {

            if (((ShadowedTextBox)elem).HasText || elem.IsFocused)

            {

                // Hide the Shadowed Label

                this.ToolTip = this.Label;

                myAdornerLayer.RemoveAdorners<AdornerLabel>(elem);  // requires AdornerExtensions.cs

            }

            else

            {

                // Show the Shadowed Label

                this.ToolTip = null;

                if (!myAdornerLayer.Contains<AdornerLabel>(elem))  // requires AdornerExtensions.cs

                    myAdornerLayer.Add(myAdornerLabel);

            }

        }

    }

}