精通Silverlight——12.5.4 添加控件事件

为控件添加事件可以分为如下所示的三步：

q      定义事件。

q      触发事件。

为了给MyLabel控件添加单击事件，需要先声明一个Click事件，代码如下：

        public event EventHandler Click;

当用户在文本上单击鼠标左键后，便触发事件，只需要在MouseLeftButton被触发时触发事件即可，代码如下所示：

         //当TextBox的鼠标左键按下时，触发事件。

        protected void MyLabel_MouseLeftButtonDown(object sender, MouseEventArgs e)

        {           

            RaiseClick();

        }

        //触过事件的函数

        private void RaiseClick()

        {

            if (Click != null)

            {

                Click(this, null);

            }

        }

代码中为触发事件定义了RaiseClick函数，在MouseLeftButtonDown事件中处理了此函数。最后，为MyLabel添加超级链接特效，完整的控件代码如下所示：

using System;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Ink;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Shapes;

using System.IO;

using System.Reflection;

namespace mySampleControls

{

    public class MyLabel : Control

    {

        #region 私有数据区

        TextBlock tb;

        FrameworkElement implementationRoot;

        SolidColorBrush sb;

        #endregion

        #region 构造函数

        public MyLabel()

        {

            //获取当前程序集实例

            Assembly asm = this.GetType().Assembly;

            //获取程序集的资源清单，注意xaml的命名。

            Stream s = asm.GetManifestResourceStream("mySampleControls.MyLabel.xaml");

            //调用InitializeFromXaml初始化控件树。

            implementationRoot = this.InitializeFromXaml(new StreamReader(s).ReadToEnd());

            //获取在Xaml中定义的TextBlock控件

            tb = implementationRoot.FindName("tb") as TextBlock;

            //定义加载事件

            this.Loaded += new EventHandler(MyLabel_Loaded);

            //指定宽和高

            base.Width = implementationRoot.Width;

            base.Height = implementationRoot.Height;

            tb.MouseLeftButtonDown += new MouseEventHandler(MyLabel_MouseLeftButtonDown);

            tb.MouseEnter += new MouseEventHandler(tb_MouseEnter);

            tb.MouseLeave += new EventHandler(tb_MouseLeave);

        }

        void tb_MouseLeave(object sender, EventArgs e)

        {

            tb.TextDecorations = TextDecorations.None;

        }

        void tb_MouseEnter(object sender, MouseEventArgs e)

        {

            tb.TextDecorations = TextDecorations.Underline;

        }      

        #endregion

        void MyLabel_Loaded(object sender, EventArgs e)

        {

            UpdateLayout();

        }

        #region 公共属性

        //定义控件的宽度

        public virtual new double Width

        {

            get

            {

                return implementationRoot.Width;

            }

            set

            {

                implementationRoot.Width = value;

                UpdateLayout();

            }

        }

        //定义控件的高度

        public virtual new double Height

        {

            get

            {

                return implementationRoot.Height;

            }

            set

            {

                implementationRoot.Height = value;               

                UpdateLayout();

            }

        }

        //定义控件的文本设置属性

        public String Text

        {

            get

            {

                return tb.Text;

            }

            set

            {

                tb.Text = value;

                UpdateLayout();

            }

        }

        //定义控件的颜色

        public SolidColorBrush LabelColor

        {

            get

            {

                return (SolidColorBrush)tb.Foreground;               

            }

            set

            {

                tb.Foreground = (SolidColorBrush)value;

            }

        }

        //定义控件的背影颜色

        public SolidColorBrush BackColor

        {

            get

            {

                return (SolidColorBrush)((Canvas)implementationRoot).Background;

            }

            set

            {

                ((Canvas)implementationRoot).Background= (SolidColorBrush)value;

                UpdateLayout();

            }

        }

        #endregion

        #region 公共事件

        public event EventHandler Click;

        #endregion

        //当TextBox的鼠标左键按下时，触发事件。

        protected void MyLabel_MouseLeftButtonDown(object sender, MouseEventArgs e)

        {           

            RaiseClick();

        }

        //触过事件的函数

        private void RaiseClick()

        {

            if (Click != null)

            {

                Click(this, null);

            }

        }

        //更新布局

        protected void UpdateLayout()

        {

            tb.SetValue(Canvas.LeftProperty, (Width - tb.ActualWidth) / 2);

            tb.SetValue(Canvas.TopProperty, (Height - tb.ActualHeight) / 2);

        }

   

    }

}