/*************************************************************************************
最近看了一下DropDownButton源码，启示意义很大，所以分享一下
Extended WPF Toolkit
Copyright (C) 2007-2013 Xceed Software Inc.
This program is provided to you under the terms of the Microsoft Public
License (Ms-PL) as published at http://wpftoolkit.codeplex.com/license
For more features, controls, and fast professional support,
pick up the Plus Edition at http://xceed.com/wpf_toolkit
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***********************************************************************************/
using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Input;
using QPP.Wpf.UI.Controls.Toolkit.Primitives;
using System.Windows.Media;
using QPP.Wpf.UI.Controls.Toolkit.Core.Utilities;
namespace QPP.Wpf.UI.Controls.Toolkit
{
[TemplatePart( Name = PART_DropDownButton, Type = typeof( ToggleButton ) )]
[TemplatePart( Name = PART_ContentPresenter, Type = typeof( ContentPresenter ) )]
[TemplatePart( Name = PART_Popup, Type = typeof( Popup ) )]
public class DropDownButton : ContentControl, ICommandSource
{
private const string PART_DropDownButton = "PART_DropDownButton";
private const string PART_ContentPresenter = "PART_ContentPresenter";
private const string PART_Popup = "PART_Popup";
#region Members
private ContentPresenter _contentPresenter;
private Popup _popup;
#endregion
#region Constructors
static DropDownButton()
{
DefaultStyleKeyProperty.OverrideMetadata( typeof( DropDownButton ), new FrameworkPropertyMetadata( typeof( DropDownButton ) ) );
}
public DropDownButton()
{
Keyboard.AddKeyDownHandler( this, OnKeyDown );
Mouse.AddPreviewMouseDownOutsideCapturedElementHandler( this, OnMouseDownOutsideCapturedElement );
}
#endregion //Constructors
#region Properties
private System.Windows.Controls.Primitives.ButtonBase _button;
protected System.Windows.Controls.Primitives.ButtonBase Button
{
get
{
return _button;
}
set
{
if( _button != null ) //删除以前的button绑定的click方法，对新的button赋值
_button.Click -= DropDownButton_Click;
_button = value;
if( _button != null )
_button.Click += DropDownButton_Click;
}
}
#region DropDownContent
public static readonly DependencyProperty DropDownContentProperty = DependencyProperty.Register( "DropDownContent", typeof( object ), typeof( DropDownButton ), new UIPropertyMetadata( null, OnDropDownContentChanged ) );
public object DropDownContent
{
get
{
return ( object )GetValue( DropDownContentProperty );
}
set
{
SetValue( DropDownContentProperty, value );
}
}
private static void OnDropDownContentChanged( DependencyObject o, DependencyPropertyChangedEventArgs e )
{
DropDownButton dropDownButton = o as DropDownButton;
if( dropDownButton != null )
dropDownButton.OnDropDownContentChanged( ( object )e.OldValue, ( object )e.NewValue );
}
protected virtual void OnDropDownContentChanged( object oldValue, object newValue )
{
// TODO: Add your property changed side-effects. Descendants can override as well.
}
#endregion //DropDownContent
#region IsOpen
public static readonly DependencyProperty IsOpenProperty = DependencyProperty.Register( "IsOpen", typeof( bool ), typeof( DropDownButton ), new UIPropertyMetadata( false, OnIsOpenChanged ) );
public bool IsOpen
{
get
{
return ( bool )GetValue( IsOpenProperty );
}
set
{
SetValue( IsOpenProperty, value );
}
}
private static void OnIsOpenChanged( DependencyObject o, DependencyPropertyChangedEventArgs e )
{
DropDownButton dropDownButton = o as DropDownButton;
if( dropDownButton != null )
dropDownButton.OnIsOpenChanged( ( bool )e.OldValue, ( bool )e.NewValue );
}
protected virtual void OnIsOpenChanged( bool oldValue, bool newValue )
{
if( newValue )
RaiseRoutedEvent( DropDownButton.OpenedEvent );
else
RaiseRoutedEvent( DropDownButton.ClosedEvent );
}
#endregion //IsOpen
#endregion //Properties
#region Base Class Overrides
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
Button = GetTemplateChild( PART_DropDownButton ) as ToggleButton;
_contentPresenter = GetTemplateChild( PART_ContentPresenter ) as ContentPresenter;
if( _popup != null )
_popup.Opened -= Popup_Opened;
_popup = GetTemplateChild( PART_Popup ) as Popup;
if( _popup != null )
_popup.Opened += Popup_Opened;
}
#endregion //Base Class Overrides
#region Events
public static readonly RoutedEvent ClickEvent = EventManager.RegisterRoutedEvent( "Click", RoutingStrategy.Bubble, typeof( RoutedEventHandler ), typeof( DropDownButton ) );
public event RoutedEventHandler Click //对事件是这么赋值的 ，创建一个事件属性
{
add
{
AddHandler( ClickEvent, value );
}
remove
{
RemoveHandler( ClickEvent, value );
}
}
public static readonly RoutedEvent OpenedEvent = EventManager.RegisterRoutedEvent( "Opened", RoutingStrategy.Bubble, typeof( RoutedEventHandler ), typeof( DropDownButton ) );
public event RoutedEventHandler Opened
{
add
{
AddHandler( OpenedEvent, value );
}
remove
{
RemoveHandler( OpenedEvent, value );
}
}
public static readonly RoutedEvent ClosedEvent = EventManager.RegisterRoutedEvent( "Closed", RoutingStrategy.Bubble, typeof( RoutedEventHandler ), typeof( DropDownButton ) );
public event RoutedEventHandler Closed
{
add
{
AddHandler( ClosedEvent, value );
}
remove
{
RemoveHandler( ClosedEvent, value );
}
}
#endregion //Events
#region Event Handlers
private void OnKeyDown( object sender, KeyEventArgs e )
{
if( !IsOpen )
{
if( KeyboardUtilities.IsKeyModifyingPopupState( e ) )
{
IsOpen = true;
// ContentPresenter items will get focus in Popup_Opened().
e.Handled = true;
}
}
else
{
if( KeyboardUtilities.IsKeyModifyingPopupState( e ) )
{
CloseDropDown( true );
e.Handled = true;
}
else if( e.Key == Key.Escape )
{
CloseDropDown( true );
e.Handled = true;
}
}
}
private void OnMouseDownOutsideCapturedElement( object sender, MouseButtonEventArgs e )
{
CloseDropDown( false );
}
private void DropDownButton_Click( object sender, RoutedEventArgs e )
{
OnClick();
}
void CanExecuteChanged( object sender, EventArgs e )
{
CanExecuteChanged();
}
private void Popup_Opened( object sender, EventArgs e )
{
// Set the focus on the content of the ContentPresenter.
if( _contentPresenter != null )
{
_contentPresenter.MoveFocus(new TraversalRequest(FocusNavigationDirection.First));
}
}
#endregion //Event Handlers
#region Methods
private void CanExecuteChanged()
{
if( Command != null )
{
RoutedCommand command = Command as RoutedCommand;
// If a RoutedCommand.
if( command != null )
IsEnabled = command.CanExecute( CommandParameter, CommandTarget ) ? true : false; //命令可用和不可用状态原来是这么控制的
// If a not RoutedCommand.
else
IsEnabled = Command.CanExecute( CommandParameter ) ? true : false;
}
}
/// <summary>
/// Closes the drop down.
/// </summary>
private void CloseDropDown( bool isFocusOnButton )
{
if( IsOpen )
IsOpen = false;
ReleaseMouseCapture();
if( isFocusOnButton )
Button.Focus();
}
protected virtual void OnClick()
{
RaiseRoutedEvent( DropDownButton.ClickEvent );
RaiseCommand(); //传播命令
}
/// <summary>
/// Raises routed events.
/// </summary>
private void RaiseRoutedEvent( RoutedEvent routedEvent )
{
RoutedEventArgs args = new RoutedEventArgs( routedEvent, this );
RaiseEvent( args );
}
/// <summary>
/// Raises the command's Execute event.
/// </summary>
private void RaiseCommand()
{
if( Command != null )
{
RoutedCommand routedCommand = Command as RoutedCommand;
if( routedCommand == null )
( ( ICommand )Command ).Execute( CommandParameter );
else
routedCommand.Execute( CommandParameter, CommandTarget );
}
}
/// <summary>
/// Unhooks a command from the Command property.
/// </summary>
/// <param name="oldCommand">The old command.</param>
/// <param name="newCommand">The new command.</param>
private void UnhookCommand( ICommand oldCommand, ICommand newCommand )
{
EventHandler handler = CanExecuteChanged;
oldCommand.CanExecuteChanged -= handler;
}
/// <summary>
/// Hooks up a command to the CanExecuteChnaged event handler.
/// </summary>
/// <param name="oldCommand">The old command.</param>
/// <param name="newCommand">The new command.</param>
private void HookUpCommand( ICommand oldCommand, ICommand newCommand )
{
EventHandler handler = new EventHandler( CanExecuteChanged );
canExecuteChangedHandler = handler;
if( newCommand != null )
newCommand.CanExecuteChanged += canExecuteChangedHandler;
}
#endregion //Methods
#region ICommandSource Members
// Keeps a copy of the CanExecuteChnaged handler so it doesn't get garbage collected.
private EventHandler canExecuteChangedHandler;
#region Command
public static readonly DependencyProperty CommandProperty = DependencyProperty.Register( "Command", typeof( ICommand ), typeof( DropDownButton ), new PropertyMetadata( ( ICommand )null, OnCommandChanged ) );
[TypeConverter( typeof( CommandConverter ) )]
public ICommand Command
{
get
{
return ( ICommand )GetValue( CommandProperty );
}
set
{
SetValue( CommandProperty, value );
}
}
private static void OnCommandChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
{
DropDownButton dropDownButton = d as DropDownButton;
if( dropDownButton != null )
dropDownButton.OnCommandChanged( ( ICommand )e.OldValue, ( ICommand )e.NewValue );
}
protected virtual void OnCommandChanged( ICommand oldValue, ICommand newValue )
{
// If old command is not null, then we need to remove the handlers.
if( oldValue != null )
UnhookCommand( oldValue, newValue );
HookUpCommand( oldValue, newValue );
CanExecuteChanged(); //may need to call this when changing the command parameter or target.
}
#endregion //Command
public static readonly DependencyProperty CommandParameterProperty = DependencyProperty.Register( "CommandParameter", typeof( object ), typeof( DropDownButton ), new PropertyMetadata( null ) );
public object CommandParameter
{
get
{
return GetValue( CommandParameterProperty );
}
set
{
SetValue( CommandParameterProperty, value );
}
}
public static readonly DependencyProperty CommandTargetProperty = DependencyProperty.Register( "CommandTarget", typeof( IInputElement ), typeof( DropDownButton ), new PropertyMetadata( null ) );
public IInputElement CommandTarget
{
get
{
return ( IInputElement )GetValue( CommandTargetProperty );
}
set
{
SetValue( CommandTargetProperty, value );
}
}
#endregion //ICommandSource Members
}
}