【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

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> < 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" >
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< TransformGroup >
< ScaleTransform x:Name ="_ScaleTransform" ScaleX ="1" ScaleY ="1" />
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StrokeThickness ="2.5" HorizontalAlignment ="Left" Margin ="-18,-63.25,0,0" x:Name ="shpPushpin"
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VerticalAlignment ="Top" Cursor ="Hand" >
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< LinearGradientBrush EndPoint ="0.5,1" StartPoint ="0.5,0" >
< GradientStop Color ="#FFFFF77F" Offset ="0" />
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</ 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：

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> /// <summary>
/// 自定义图钉控件
/// </summary>
public class PushPinControl:ContentControl
{
private string Text;

public PushPinControl(Stringtext)
{
// 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
vartextBlock = 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
varToolPanelBorder = 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：

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> private void AddPushPin()
{
// 添加BingMapsSilverlightControl自带的图钉
// varpushpin=newPushpin();
// pushpin.Location=newLocation(29.5076372217973,106.489384971208);
// 添加自定义的图钉
varpushpin = 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：

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> < 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：

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> public delegate void PushpinContentChangedHandler( object sender,PushpinContentChangedEvantAgrse);

public class PushpinContentChangedEvantAgrs:EventArgs
{
public BorderContentBorder{ get ; set ;}

public PushpinContentChangedEvantAgrs(){}

public PushpinContentChangedEvantAgrs(BorderContentBorder)
{
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.

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> /// <summary>
/// 自定义图钉控件
/// </summary>
public class PushPinControl:ContentControl
{
public event PushpinContentChangedHandlerContentChangedEvent;

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：

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> public override void OnApplyTemplate()
{
base .OnApplyTemplate();

// 从样式模板中获取TextBlock控件
vartextBlock = 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
varToolPanelBorder = 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
varContentBorder = 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。

<!--<br/ /><br/ />Code highlighting produced by Actipro CodeHighlighter (freeware)<br/ />http://www.CodeHighlighter.com/<br/ /><br/ />--> private void AddPushPin()
{
// 添加BingMapsSilverlightControl自带的图钉
// varpushpin=newPushpin();
// pushpin.Location=newLocation(29.5076372217973,106.489384971208);
// 添加自定义的图钉
varpushpin = new PushPinControl( " D " );
pushpin.ContentChangedEvent += (sender,o) =>
{
// 构造Image对象用于显示在ToolPanel中
varimage = new Image{Width = 100 ,Height = 100 ,Margin = new Thickness( 8 )};
image.Source = new BitmapImage( new Uri( " Resources/Smbecker.png " ,UriKind.RelativeOrAbsolute));
Borderborder = 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/