【Silverlight】Bing Maps开发应用与技巧二：自定义图钉标注控件和动态ToolPanel

　　在Bing Maps Silverlight Control中以及为我们提供了地图图钉控件Pushpin，我曾经在《 使用图钉层（Pushpin layer）及地图图层（MapLayer）》一文中介绍过他的使用方法，本篇主要介绍如何自定义图钉标注控件以及对他的一些扩展，比如实现图钉的动态ToolPanel。

 

　　关于图钉的UI外观的设计这里就不详细介绍了，通过Blend可以快速的构建UI界面。首先介绍下我的实现思想，通过Path构建图钉标注控件的UI外观，控件整体布局使用Grid布局，分别在Grid容器里设计好图钉UI外观效果和需要动态提示的ToolPanel(使用Border布局设计)，默认将ToolPanel隐藏，在后台代码中通过鼠标事件进行控制其是否出现；另外还布局了一个TextBlock控件，用于出现图钉标注上的内容。下面是定义好的图钉风格的样式：

自定义图钉样式

< Style  x:Name ="PushpinStyle"  TargetType ="Controls:PushPinControl" >
     < Setter  Property ="Template" >
         < Setter.Value >
             < ControlTemplate  TargetType ="Controls:PushPinControl" >
                 < Grid  x:Name ="grdRoot"  Height ="Auto"  Width ="Auto"  HorizontalAlignment ="Stretch"  RenderTransformOrigin ="0,0" >
                     < Grid.RenderTransform >
                         < TransformGroup >
                             < ScaleTransform  x:Name ="_ScaleTransform"  ScaleX ="1"  ScaleY ="1" />
                             < SkewTransform />
                             < RotateTransform />
                             < TranslateTransform />
                         </ TransformGroup >
                     </ Grid.RenderTransform >
                     < Path  Stretch ="Fill"  Opacity ="1"  RenderTransformOrigin ="0.501,0.281"  Data ="M0,-250L6.09909264359567,
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                             < TransformGroup >
                                 < ScaleTransform  ScaleX ="1"  ScaleY ="1" />
                                 < SkewTransform  AngleX ="-57.547"  AngleY ="0" />
                                 < RotateTransform  Angle ="0" />
                                 < TranslateTransform  X ="45.252"  Y ="0" />
                             </ TransformGroup >
                         </ Path.RenderTransform >
                     </ Path >
                     < Path  Stretch ="Fill"  Stroke ="#FF000000"  Opacity ="1"  RenderTransformOrigin ="0.501,0.281"  
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                          StrokeThickness ="2.5"  HorizontalAlignment ="Left"  Margin ="-18,-63.25,0,0"  x:Name ="shpPushpin"  
                          Width ="35"  d:LayoutOverrides ="Width"  Height ="63"  
                          VerticalAlignment ="Top"  Cursor ="Hand" >
                         < Path.RenderTransform >
                             < TransformGroup >
                                 < ScaleTransform  ScaleX ="1"  ScaleY ="1" />
                                 < SkewTransform  AngleX ="0"  AngleY ="0" />
                                 < RotateTransform  Angle ="0" />
                                 < TranslateTransform  X ="0"  Y ="0" />
                             </ TransformGroup >
                         </ Path.RenderTransform >
                         < Path.Fill >
                             < LinearGradientBrush  EndPoint ="0.5,1"  StartPoint ="0.5,0" >
                                 < GradientStop  Color ="#FFFFF77F"  Offset ="0" />
                                 < GradientStop  Color ="#FFFCF14E"  Offset ="1" />
                             </ LinearGradientBrush >
                         </ Path.Fill >
                     </ Path >
                     < TextBlock  TextWrapping ="Wrap"  d:LayoutOverrides ="Height, GridBox"  RenderTransformOrigin ="0.51,0.491"  VerticalAlignment ="Top"  
                           TextAlignment ="Center"  Margin ="-15.55,-60,0,0"  x:Name ="txtTitle"
                           Width ="30"  FontSize ="24"  Visibility ="Visible"  FontFamily ="Verdana"  HorizontalAlignment ="Left"  IsHitTestVisible ="False"   >
                             < TextBlock.RenderTransform >
                                 < TransformGroup >
                                     < ScaleTransform />
                                     < SkewTransform  AngleX ="0"  AngleY ="0" />
                                     < RotateTransform  Angle ="0" />
                                     < TranslateTransform  X ="0"  Y ="0" />
                                 </ TransformGroup >
                             </ TextBlock.RenderTransform >
                     </ TextBlock >
                     < Border  x:Name ="ToolPanel"  VerticalAlignment ="Stretch"  Background ="#A82D2D2D"  CornerRadius ="8,8,8,8"  Visibility ="Collapsed"  
                        BorderBrush ="#FF626262"  BorderThickness ="2,2,2,2"  ScrollViewer.HorizontalScrollBarVisibility ="Visible"  
                        RenderTransformOrigin ="0.5,0.5"  Grid.Row ="0"  Width ="300"  Height ="200" >
                         < Border.RenderTransform >
                             < TransformGroup >
                                 < ScaleTransform />
                                 < SkewTransform />
                                 < RotateTransform />
                                 < TranslateTransform  X ="20"  Y ="-75" />
                             </ TransformGroup >
                         </ Border.RenderTransform >
                         < StackPanel  VerticalAlignment ="Top"  Margin ="5,10, 5, 10" >
                             < Grid  Height ="29"  VerticalAlignment ="Top" >
                                 < TextBlock  Height ="25"  Width ="346"  Text ="标题内容"  TextWrapping ="Wrap"  Foreground ="#FFF0E7E7"  FontSize ="16"  
                                    HorizontalAlignment ="Left"  Margin ="12,3,0,1" />
                             </ Grid >
                             < StackPanel  VerticalAlignment ="Top" >
                                 < Border  x:Name ="ContentBorder"  Background ="#FF000000"  CornerRadius ="8,8,8,8"  VerticalAlignment ="Top"
                                        Margin ="0,3,0,3"  Padding ="0,8,0,8"  Opacity ="0.68"  MinHeight ="200" >
                                     < TextBlock  Text ="显示内容"  Foreground ="White"  Margin ="3"   ></ TextBlock >
                                 </ Border >
                             </ StackPanel >
                         </ StackPanel >
                     </ Border >
                 </ Grid >
             </ ControlTemplate >
         </ Setter.Value >
     </ Setter >
</ Style >

 

　　接下来要做的就是实现图标注控件的定义以及动态控制ToolPanel控件的显示与否了，主要思路就是通过引用上面定义的样式，以模板的方式从样式里获取到相应的控件元素进行动态控制，详细见如下代码：

///   <summary>
///  自定义图钉控件
///   </summary>
public   class  PushPinControl : ContentControl
{
     private   string  Text;

     public  PushPinControl(String text)
    {
         // 设置图钉标注控件的标注内容
         this .Text  =  text  ==   ""   ?   " M "  : text;
        DefaultStyleKey  =   typeof (PushPinControl);
         // 为当前对象引用样式，从全局资源里读取
         this .Style  =  Application.Current.Resources[ " PushpinStyle " ]  as  Style;
    }

     public   override   void  OnApplyTemplate()
    {
         base .OnApplyTemplate();

         // 从样式模板中获取TextBlock控件
        var textBlock  =  GetTemplateChild( " txtTitle " )  as  TextBlock;
        textBlock.Text  =   this .Text;
         // 从样式模板中获取ToolPanel(既Border布局实现的，详细见样式的定义)控件
        var ToolPanelBorder  =  GetTemplateChild( " ToolPanel " )  as  Border;
         // 通过事件动态控制ToolPanel的显示和隐藏
         this .MouseEnter  +=  (mes, meo)  =>  { ToolPanelBorder.Visibility  =  Visibility.Visible; };
         this .MouseLeave  +=  (mls, mlo)  =>  { ToolPanelBorder.Visibility  =  Visibility.Collapsed; };
    }
}

 　　　　　　　

　　到这里就成功的完成了图钉标注控件的自定义了，接下来看看如何使用这个自定义的图钉标注控件，详见如下代码块：

private   void  AddPushPin()
{
     // 添加Bing Maps Silverlight Control自带的图钉
     // var pushpin = new Pushpin();
     // pushpin.Location = new Location(29.5076372217973, 106.489384971208);
     // 添加自定义的图钉
    var pushpin  =   new  PushPinControl( " D " );
    MapLayer.AddChild(pushpin,  new  Location( 29.5076372217973 ,  106.489384971208 ));
}

 

　　　　　　　

 

　　或许会有人问道，如何动态的实现ToolPanel里显示的内容？要实现这个功能也是非常简单的，首先我们来分析下上面定义的样式里对ToolPanel部分的定义：

< Border  x:Name ="ToolPanel"  VerticalAlignment ="Stretch"  Background ="#A82D2D2D"  CornerRadius ="8,8,8,8"  Visibility ="Collapsed"  
    BorderBrush ="#FF626262"  BorderThickness ="2,2,2,2"  ScrollViewer.HorizontalScrollBarVisibility ="Visible"  
    RenderTransformOrigin ="0.5,0.5"  Grid.Row ="0"  Width ="300"  Height ="200" >
     < Border.RenderTransform >
         < TransformGroup >
             < ScaleTransform />
             < SkewTransform />
             < RotateTransform />
             < TranslateTransform  X ="20"  Y ="-75" />
         </ TransformGroup >
     </ Border.RenderTransform >
     < StackPanel  VerticalAlignment ="Top"  Margin ="5,10, 5, 10" >
         < Grid  Height ="29"  VerticalAlignment ="Top" >
             < TextBlock  Height ="25"  Width ="346"  Text ="标题内容"  TextWrapping ="Wrap"  Foreground ="#FFF0E7E7"  FontSize ="16"  
                HorizontalAlignment ="Left"  Margin ="12,3,0,1" />
         </ Grid >
         < StackPanel  VerticalAlignment ="Top" >
             < Border  x:Name ="ContentBorder"  Background ="#FF000000"  CornerRadius ="8,8,8,8"  VerticalAlignment ="Top"
                    Margin ="0,3,0,3"  Padding ="0,8,0,8"  Opacity ="0.68"  MinHeight ="200" >
                 < TextBlock  Text ="显示内容"  Foreground ="White"  Margin ="3"   ></ TextBlock >
             </ Border >
         </ StackPanel >
     </ StackPanel >
</ Border >

 

　　使用了Border进行圆角布局，在其内部通过StackPanel垂直布局实现了ToolPanel的的标题和内容两大部分，内容部分并通过Border进行设计，取名为ContentBorder，这是为了实现动态呈现显示内容而设计，整体Border通过 TranslateTransform进行一个偏移的处理，也就是让ToolPanel始终显示在图钉标注的右边相应的位置，详细见本文前面提供的截图。

 

　　从上面的实现知道ToolPanel是在鼠标的MouseEnter事件执行的时候才会显示的，当鼠标离开就会将其可见性设置为隐藏。了解了这个原理后就可以想到，是否可以从MouseEnter事件中通过某种方法去处理？事件是个非常强大的技术点，这里我们就可以通过事件，将显示内容的Border容器派发处理，通过事件的监听来动态更新其显示内容。首先需要扩展一个事件类：

public   delegate   void  PushpinContentChangedHandler( object  sender,PushpinContentChangedEvantAgrs e);

public   class  PushpinContentChangedEvantAgrs : EventArgs
{
     public  Border ContentBorder {  get ;  set ; }

     public  PushpinContentChangedEvantAgrs() { }

     public  PushpinContentChangedEvantAgrs(Border ContentBorder)
    {
         this .ContentBorder  =  ContentBorder;
    }
}

 

     接下来为自定义的图钉标注类定义一个事件，事件类型就为上面所定义好的委托类型，传递的事件为PushpinContentChangedEventArgs.

///   <summary>
///  自定义图钉控件
///   </summary>
public   class  PushPinControl : ContentControl
{
     public   event  PushpinContentChangedHandler ContentChangedEvent;

    现在需要做的就是在当前对象的MouseEnter事件中去触发这个事件，将样式里所定义好的用于显示内容的Border对象获取出来，通过事件参数传递派发出去，让事件监听段可以通过该事件获取事件参数进行ToolPanel内容的呈现更新。所有我们需要改写PushPinControl的OnApplyTemplate方法：

public   override   void  OnApplyTemplate()
{
     base .OnApplyTemplate();

     // 从样式模板中获取TextBlock控件
    var textBlock  =  GetTemplateChild( " txtTitle " )  as  TextBlock;
    textBlock.Text  =   this .Text;
     // 从样式模板中获取ToolPanel(既Border布局实现的，详细见样式的定义)控件
    var ToolPanelBorder  =  GetTemplateChild( " ToolPanel " )  as  Border;
     // 获取内容Border对象，通过事件将该对象派发出去，在使用段可以通过监听这个事件而获取到内容Border
    var ContentBorder  =  GetTemplateChild( " ContentBorder " )  as  Border;
     // 通过事件动态控制ToolPanel的显示和隐藏
     this .MouseEnter  +=  (mes, meo)  =>  
    { 
        ToolPanelBorder.Visibility  =  Visibility.Visible;  
         if  (ContentChangedEvent  !=   null )
        {
            ContentChangedEvent( this ,  new  PushpinContentChangedEvantAgrs(ContentBorder));
        }
    };
     this .MouseLeave  +=  (mls, mlo)  =>  { ToolPanelBorder.Visibility  =  Visibility.Collapsed; };
}

 

 　　通过ContentChangedEvent事件的监听动态的去改变ToolPanel里的显示内容就可以达到我们的目的了，比如我们动态的将ToolPanel里的显示内容更改为一张图片，上面使用自定义图钉标注的代码将变成下面这样的。

 

private   void  AddPushPin()
{
     // 添加Bing Maps Silverlight Control自带的图钉
     // var pushpin = new Pushpin();
     // pushpin.Location = new Location(29.5076372217973, 106.489384971208);
     // 添加自定义的图钉
    var pushpin  =   new  PushPinControl( " D " );
    pushpin.ContentChangedEvent  +=  (sender, o)  =>
        {
             // 构造Image对象 用于显示在ToolPanel中
            var image  =   new  Image { Width  =   100 , Height  =   100 , Margin  =   new  Thickness( 8 ) };
            image.Source  =   new  BitmapImage( new  Uri( " Resources/Smbecker.png " , UriKind.RelativeOrAbsolute));
            Border border  =  o.ContentBorder;

            border.Child  =  image;
        };
    MapLayer.AddChild(pushpin,  new  Location( 29.5076372217973 ,  106.489384971208 ));
}

 

　　　　　　　　  

 

　　之前有网友问到如何实现可拖拽的图钉标注控件，鉴于篇幅的原因这里就不做介绍，不清楚的朋友可以留言讨论。本篇就介绍到这里，欢迎大家前来交流、讨论、拍砖。

 

　　更多学习资料：

　　MSDN: http://msdn.microsoft.com/en-us/library/ee681890.aspx

　　官方： http://www.microsoft.com/maps

　　中国Bing Maps: http://cn.bing.com/ditu/

　　官方SDK： http://www.microsoft.com/maps/isdk/silverlight/