Behavior的使用

Behavior

• Behavior将某些特定的功能从某个特定的控件中解耦出来，重用性高

利用behavior实现以下功能

• 点击某个控件 正常产生某个控件的事件
• 点击某个控件并移动鼠标， 拖动整个窗口

• 效果图如下

  
  dragwindow.gif
• 源码
• 相关连接

代码

• 定义一个类 继承抽象类 Behavior<T>（包含在System.Windows.Interactivity.dll中）
• 重写两个方法 OnAttached 和 OnDetaching 获取一个宿主控件对象AssociatedObject
• 以下是behavior的代码

public class WinDragMoveBehavior: Behavior<Window>
    {
        #region Fields

        private Point _downPoint;

        #endregion Fields

        #region Properties

        public Window AttachedWindow { get; set; }

        #endregion Properties

        #region Methods

        protected override void OnAttached()
        {
            base.OnAttached();
            AttachedWindow = AssociatedObject as Window;

            if (AttachedWindow == null)
            {
                return;
            }

            RegisterEvents();
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();

            UnRegisterEvents();
        }

        /// <summary>
        ///  注册事件
        /// </summary>
        private void RegisterEvents()
        {
            if (AttachedWindow != null)
            {
                AttachedWindow.PreviewMouseLeftButtonDown += AttachedGrid_PreviewMouseLeftButtonDown;
                AttachedWindow.PreviewMouseMove += AttachedGridOnPreviewMouseMove;
                AttachedWindow.PreviewMouseLeftButtonUp += AttachedGridOnPreviewMouseLeftButtonUp;
            }
        }

        /// <summary>
        /// 注销事件
        /// </summary>
        private void UnRegisterEvents()
        {
            if (AttachedWindow != null)
            {
                AttachedWindow.MouseLeftButtonDown -= AttachedGrid_PreviewMouseLeftButtonDown;
                AttachedWindow.MouseMove -= AttachedGridOnPreviewMouseMove;
                AttachedWindow.MouseLeftButtonUp -= AttachedGridOnPreviewMouseLeftButtonUp;
            }
        }

        #endregion Methods

        #region EventHandlers

        private void AttachedGrid_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            _downPoint = e.GetPosition(AttachedWindow);
        }

        private void AttachedGridOnPreviewMouseMove(object sender, MouseEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                var mouseMovePoint = e.GetPosition(AttachedWindow);

                if (AppUtils.IsAbleToDrag(mouseMovePoint, _downPoint))
                {
                    AttachedWindow.DragMove();
                }
            }
        }

        private void AttachedGridOnPreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            var mouseMovePoint = e.GetPosition(AttachedWindow);

            if (AppUtils.IsAbleToDrag(mouseMovePoint, _downPoint))
            {
                e.Handled = true;

                var element = Mouse.Captured;
                element?.ReleaseMouseCapture();
            }
        }

        #endregion EventHandlers
    }

• 使用此behavior

 xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
 xmlns:behavior="clr-namespace:DragAndClickWinSamples.Behaviors"
<i:Interaction.Behaviors>
        <behavior:WinDragMoveBehavior></behavior:WinDragMoveBehavior>
</i:Interaction.Behaviors>