Silverlight 解谜游戏 之十一 鼠标的新衣

       本篇我们将对鼠标指针进行美化，也给它穿上好看点的马甲，对于其样式来源可以选择Image 或Path。可以通过微软的 Expression Design 设计出鼠标指针样式。

   

先看看鼠标指针换上新装的效果：

 

1. 将鼠标指针图片加入Images 文件夹：

2. 在Interactivity 中创建MouseCursor 文件夹，并在其中加入MouseCursorBehavior、NameResolvedEventArgs、NameResolver 类：

3. 在NameResolver 类中，最关键的就是UpdateObjectFromName 方法，它将CursorName 属性与鼠标指针对象结合起来：

private void UpdateObjectFromName(DependencyObject oldObject)
{
   DependencyObject resolvedObject = null;
   this.ResolvedObject = null;

   if (this.NameScopeReferenceElement != null)
   {
      if (!IsElementLoaded(this.NameScopeReferenceElement))
      {
          this.NameScopeReferenceElement.Loaded += 
            new RoutedEventHandler(this.OnNameScopeReferenceLoaded);
          this.PendingReferenceElementLoad = true;
          return;
      }
      if (!string.IsNullOrEmpty(this.Name))
      {
          FrameworkElement actualNameScopeReferenceElement = 
            this.ActualNameScopeReferenceElement;
          if (actualNameScopeReferenceElement != null)
          {
             resolvedObject = actualNameScopeReferenceElement.FindName(this.Name) 
                as DependencyObject;
          }
      }
   }
   this.HasAttempedResolve = true;
   this.ResolvedObject = resolvedObject;
   if (oldObject != this.Object)
   {
      this.OnObjectChanged(oldObject, this.Object);
   }
}

4. 在MouseCursorBehavior 类中，存有CursorName、OffsetX、OffsetY 属性，它们将用于在Blend 中对鼠标指针进行设置：

public static readonly DependencyProperty CursorNameProperty = 
  DependencyProperty.Register("CursorName", typeof(string), typeof(MouseCursorBehavior), 
  new PropertyMetadata(new PropertyChangedCallback(OnCursorNameChanged)));

public static readonly DependencyProperty OffsetXProperty =
  DependencyProperty.Register("OffsetX", typeof(double), typeof(MouseCursorBehavior), null);

public static readonly DependencyProperty OffsetYProperty =
  DependencyProperty.Register("OffsetY", typeof(double), typeof(MouseCursorBehavior), null);

以及MouseEnter、MouseLeave、MouseMove 事件：

private void AssociatedObject_MouseEnter(object sender, MouseEventArgs e)
{
   if (!this.IsCursorNameSet)
      return;

   FrameworkElement cursor = Cursor as FrameworkElement;
   cursor.IsHitTestVisible = false;
   cursor.Visibility = Visibility.Visible;

   if (CursorStack.Count > 0 && CursorStack.Peek() != cursor)
   {
      CursorStack.Peek().Visibility = Visibility.Collapsed;
   }

   if (!CursorStack.Contains(cursor))
      CursorStack.Push(cursor);

   AssociatedObject.Cursor = Cursors.None;

   this.AssociatedObject.MouseMove += new MouseEventHandler(AssociatedObject_MouseMove);
}

private void AssociatedObject_MouseLeave(object sender, MouseEventArgs e)
{
   if (!this.IsCursorNameSet)
      return;

   FrameworkElement cursor = Cursor as FrameworkElement;
   cursor.Visibility = Visibility.Collapsed;

   CursorStack.Pop();

   if (CursorStack.Count > 0)
   {
      CursorStack.Peek().Visibility = Visibility.Visible;
   }

   this.AssociatedObject.MouseMove -= new MouseEventHandler(AssociatedObject_MouseMove);
   AssociatedObject.Cursor = null;
}

private void AssociatedObject_MouseMove(object sender, MouseEventArgs e)
{
   if (!this.IsCursorNameSet)
      return;

   FrameworkElement cursor = Cursor as FrameworkElement;

   Point mousePosition = e.GetPosition(null);
   cursor.Margin = new Thickness(mousePosition.X + OffsetX, mousePosition.Y + OffsetY, 0, 0);

}

5. 添加好上面三个类并重新编译后，我们回到Blend 中，为UserControl 添加新的Behavior->MouseCursorBehavior：

6. 在LayoutRoot 中添加鼠标指针图片，命名为cursorArrow：

将其放在GameScreen 上方，Left 设为0，Top 设为-50：

7. 选择刚刚添加的MouseCursorBehavior 将CursorName 设为鼠标指针名称cursorArrow，OffsetY 设为50（因为之前它与LayoutRoot有-50的偏差）：

运行程序便可看到新的鼠标指针效果，源代码下载：