【发布时间】：2016-07-03 19:33:01
【问题描述】：
在我的 WPF 应用程序中，我有几个带有大量输入字段的表单供用户使用。事实证明，并非每个用户都需要所有字段，具体取决于其公司的流程，因此我有一个新要求，允许用户根据自己的需要隐藏字段。
我计划为此使用一个行为，它可以附加到基本上每个 WPF 控件。该行为将向每个控件添加一个 ContextMenu，以允许显示/隐藏所有可用字段。我目前看起来运行良好的测试项目有四个 DependencyProperties 来使一切正常：
- 字符串 VisibilityGroupName：
这以某种方式作为每个字段的 ID，但不是唯一的，以便将多个字段组合在一起（例如，字段标题的标签到其相应的文本框）。此字符串当前也用作用户在 ContextMenu 中看到的名称。
- 字典可见性字典：
此字典跟踪字段的所有可见性状态。在我的应用程序中，我将把它序列化为 XML，以使用户的决策持久化。
- bool AllowCustomVisibility：
这只是一个标志，用于关闭整个功能。
- bool NotificationDummy：
这就是有趣的地方。目前，我将此属性与 ValueChanged 事件结合使用，以通知所有控件状态已更改，以便他们检查是否受到影响。虽然这按预期工作，但我知道这只是一个糟糕的解决方法，因为我不知道如何正确完成通知。
有人知道它是如何正确完成的吗？我已经用 TODO 标记了代码中的相应位置：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Interactivity;
namespace CustomizableUserControlVisibility
{
public class WPFCustomVisibilityBehavior : Behavior<DependencyObject>
{
#region Fields
private Control _control = null;
private ContextMenu _contextMenu;
private bool _contextMenuIsBuilt = false;
#endregion
#region Properties
public bool NotificationDummy
{
get { return (bool)GetValue(NotificationDummyProperty); }
set { SetValue(NotificationDummyProperty, value); }
}
public static readonly DependencyProperty NotificationDummyProperty = DependencyProperty.Register("NotificationDummy", typeof(bool), typeof(WPFCustomVisibilityBehavior), new PropertyMetadata(false));
public bool AllowCustomVisibility
{
get { return (bool)GetValue(AllowCustomVisibilityProperty); }
set { SetValue(AllowCustomVisibilityProperty, value); }
}
public static readonly DependencyProperty AllowCustomVisibilityProperty = DependencyProperty.Register("AllowCustomVisibility", typeof(bool), typeof(WPFCustomVisibilityBehavior), new PropertyMetadata(false));
public string VisibilityGroupName
{
get { return (string)GetValue(VisibilityGroupNameProperty); }
set { SetValue(VisibilityGroupNameProperty, value); }
}
public static readonly DependencyProperty VisibilityGroupNameProperty = DependencyProperty.Register("VisibilityGroupName", typeof(string), typeof(WPFCustomVisibilityBehavior), new PropertyMetadata(string.Empty));
public Dictionary<string, bool> VisibilityDictionary
{
get { return (Dictionary<string, bool>)GetValue(VisibilityDictionaryProperty); }
set { SetValue(VisibilityDictionaryProperty, value); }
}
public static readonly DependencyProperty VisibilityDictionaryProperty = DependencyProperty.Register("VisibilityDictionary", typeof(Dictionary<string, bool>), typeof(WPFCustomVisibilityBehavior), new PropertyMetadata(new Dictionary<string, bool>()));
#endregion
#region Constructor
public WPFCustomVisibilityBehavior()
{
// TODO: There should be a better way to notify other controls about state changes than this...
var temp = DependencyPropertyDescriptor.FromProperty(WPFCustomVisibilityBehavior.NotificationDummyProperty, typeof(WPFCustomVisibilityBehavior));
if (temp != null)
{
temp.AddValueChanged(this, OnNotificationDummyChanged);
}
}
#endregion
#region Overrrides
protected override void OnAttached()
{
base.OnAttached();
if (this.AllowCustomVisibility == false)
{
return;
}
this._control = this.AssociatedObject as Control;
if (!string.IsNullOrEmpty(this.VisibilityGroupName) && this._control != null)
{
if (this.VisibilityDictionary.ContainsKey(this.VisibilityGroupName))
{
if (this.VisibilityDictionary[this.VisibilityGroupName])
{
this._control.Visibility = Visibility.Visible;
}
else
{
this._control.Visibility = Visibility.Collapsed;
}
}
else
{
this.VisibilityDictionary.Add(this.VisibilityGroupName, this._control.Visibility == Visibility.Visible ? true : false);
}
// Add a ContextMenu to the Control, but only if it does not already have one (TextBox brings its default ContextMenu for copy, cut and paste)
if (this._control.ContextMenu == null && !(this._control is TextBox))
{
this._contextMenu = new ContextMenu();
ContextMenuService.SetContextMenu(this._control, this._contextMenu);
this._control.ContextMenuOpening += (sender, e) => { ContextMenuOpening(e); };
}
}
}
#endregion
#region Event handling
private void ContextMenuOpening(ContextMenuEventArgs e)
{
if (this._contextMenuIsBuilt == false)
{
this._contextMenu.Items.Clear();
Dictionary<string, MenuItem> menuItems = new Dictionary<string, MenuItem>();
foreach (string k in this.VisibilityDictionary.Keys)
{
MenuItem menuItem = new MenuItem() { Header = k, Name = k, IsCheckable = true, StaysOpenOnClick = true };
menuItem.Click += MenuItem_Click;
menuItems.Add(k, menuItem);
}
var keyList = menuItems.Keys.ToList();
keyList.Sort();
foreach (string key in keyList)
{
this._contextMenu.Items.Add(menuItems[key]);
}
this._contextMenuIsBuilt = true;
}
foreach (MenuItem mi in this._contextMenu.Items)
{
mi.IsChecked = this.VisibilityDictionary[mi.Name];
}
}
private void MenuItem_Click(object sender, RoutedEventArgs e)
{
MenuItem mi = sender as MenuItem;
if (mi != null && this.VisibilityDictionary != null && this.VisibilityDictionary.ContainsKey(mi.Name))
{
this.VisibilityDictionary[mi.Name] = mi.IsChecked;
// TODO: There should be a better way to notify other controls about state changes than this...
this.NotificationDummy = !NotificationDummy;
}
}
private void OnNotificationDummyChanged(object sender, EventArgs args)
{
// TODO: There should be a better way to notify other controls about state changes than this...
if (this._control != null && this.VisibilityDictionary != null && !string.IsNullOrEmpty(this.VisibilityGroupName))
{
if (this.VisibilityDictionary.ContainsKey(this.VisibilityGroupName))
{
if (this.VisibilityDictionary[this.VisibilityGroupName])
{
this._control.Visibility = Visibility.Visible;
}
else
{
this._control.Visibility = Visibility.Collapsed;
}
}
}
}
#endregion
}
}
【问题讨论】：
标签： c# .net wpf behavior attachedbehaviors