【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

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StrokeThickness="2.5"HorizontalAlignment="Left"Margin="-18,-63.25,0,0"x:Name="shpPushpin"
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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>
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<RotateTransformAngle="0"/>
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</TextBlock.RenderTransform>
</TextBlock>
<Borderx: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/>
<TranslateTransformX="20"Y="-75"/>
</TransformGroup>
</Border.RenderTransform>
<StackPanelVerticalAlignment="Top"Margin="5,10,5,10">
<GridHeight="29"VerticalAlignment="Top">
<TextBlockHeight="25"Width="346"Text="标题内容"TextWrapping="Wrap"Foreground="#FFF0E7E7"FontSize="16"
HorizontalAlignment="Left"Margin="12,3,0,1"/>
</Grid>
<StackPanelVerticalAlignment="Top">
<Borderx: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">
<TextBlockText="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>
publicclassPushPinControl:ContentControl
{
privatestringText;

publicPushPinControl(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"]asStyle;
}

publicoverridevoidOnApplyTemplate()
{
base.OnApplyTemplate();

//从样式模板中获取TextBlock控件
vartextBlock=GetTemplateChild("txtTitle")asTextBlock;
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")asBorder;
//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/ />-->privatevoidAddPushPin()
{
//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=newPushPinControl("D");
MapLayer.AddChild(pushpin,newLocation(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/ />--><Borderx: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/>
<TranslateTransformX="20"Y="-75"/>
</TransformGroup>
</Border.RenderTransform>
<StackPanelVerticalAlignment="Top"Margin="5,10,5,10">
<GridHeight="29"VerticalAlignment="Top">
<TextBlockHeight="25"Width="346"Text="标题内容"TextWrapping="Wrap"Foreground="#FFF0E7E7"FontSize="16"
HorizontalAlignment="Left"Margin="12,3,0,1"/>
</Grid>
<StackPanelVerticalAlignment="Top">
<Borderx: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">
<TextBlockText="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/ />-->publicdelegatevoidPushpinContentChangedHandler(objectsender,PushpinContentChangedEvantAgrse);

publicclassPushpinContentChangedEvantAgrs:EventArgs
{
publicBorderContentBorder{get;set;}

publicPushpinContentChangedEvantAgrs(){}

publicPushpinContentChangedEvantAgrs(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>
publicclassPushPinControl:ContentControl
{
publiceventPushpinContentChangedHandlerContentChangedEvent;

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/ />-->publicoverridevoidOnApplyTemplate()
{
base.OnApplyTemplate();

//从样式模板中获取TextBlock控件
vartextBlock=GetTemplateChild("txtTitle")asTextBlock;
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")asBorder;
//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")asBorder;
//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,newPushpinContentChangedEvantAgrs(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/ />-->privatevoidAddPushPin()
{
//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=newPushPinControl("D");
pushpin.ContentChangedEvent+=(sender,o)=>
{
//构造Image对象用于显示在ToolPanel中
varimage=newImage{Width=100,Height=100,Margin=newThickness(8)};
image.Source=newBitmapImage(newUri("Resources/Smbecker.png",UriKind.RelativeOrAbsolute));
Borderborder=o.ContentBorder;

border.Child=image;
};
MapLayer.AddChild(pushpin,newLocation(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/