从零开始Windows Phone开发（三）：第三个练习-IN_CASE_OF_EMERGENCY

今天的练习是创建一个“紧急状况”的项目，涉及到的知识点有：屏幕的旋转，SIP（屏幕键盘）及处理按键时间，滚动视图，电话启动器。

1 界面设计

我们希望设计出来的界面是这样的：

当单击页面红色的标题时，拨号启动器被调用。各个文本框拥有自己的输入域，并且获得焦点的那个文本框默认全选文字。

1.1 涉及到的滚动视图问题

使用一个ScrollViewer将需要滚动的控件包裹在其中即可

1.2 输入域的问题

文本框的InputScope属性提供了11种不同类型的屏幕键盘，需要根据具体情况调用相应的键盘，通常需要实现导航到此页面自动弹出，通过处理回车事件达到额外的操作，限制输入值（需要手写代码）。

界面的代码如下所示：

<phone:PhoneApplicationPage 
    x:Class="IN_CASE_OF_EMERGENCY.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="PortraitOrLandscape"
    shell:SystemTray.IsVisible="True">

    <!--LayoutRoot is the root grid where all page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="IN CASE OF EMERGENCY" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock x:Name="PageTitle" Text="tab here to dial!" Margin="9,-7,0,0" FontSize="64" Foreground="Red" MouseLeftButtonUp="PageTitle_MouseLeftButtonUp"/>
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <ScrollViewer Grid.Row="1">
            <StackPanel Orientation="Vertical">
                <TextBlock Text="Emergency contact people" Foreground="{StaticResource PhoneSubtleBrush}" Margin="24,5,0,2"/>
                <TextBox x:Name="Ecp" InputScope="PersonalFullName" Margin="{StaticResource PhoneHorizontalMargin}" KeyDown="BoxKeyDown_Event" GotFocus="Box_GotFocus"/>
                <TextBlock Text="Emergency contact people number" Foreground="{StaticResource PhoneSubtleBrush}" Margin="24,5,0,2"/>
                <TextBox x:Name="Ecn" InputScope="TelephoneNumber" Margin="{StaticResource PhoneHorizontalMargin}" KeyDown="BoxKeyDown_Event" GotFocus="Box_GotFocus"/>
                <TextBlock Text="Phone owner name" Foreground="{StaticResource PhoneSubtleBrush}" Margin="24,5,0,2"/>
                <TextBox x:Name="Pon" InputScope="PersonalFullName" Margin="{StaticResource PhoneHorizontalMargin}" KeyDown="BoxKeyDown_Event" GotFocus="Box_GotFocus" />
                <TextBlock Text="Phone owner's medical notes" Foreground="{StaticResource PhoneSubtleBrush}" Margin="24,5,0,2"/>
                <TextBox x:Name="Pomn" InputScope="Text" Margin="{StaticResource PhoneHorizontalMargin}" AcceptsReturn="True"  TextWrapping="Wrap" MinHeight="250" KeyDown="BoxKeyDown_Event" GotFocus="Box_GotFocus"/>          
            </StackPanel>
        </ScrollViewer>
    </Grid>
</phone:PhoneApplicationPage>

2 后端代码

2.1 实现拨号启动器的功能

        private void PageTitle_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            PhoneCallTask phoneLauncher = new PhoneCallTask();
            phoneLauncher.DisplayName = this.Ecp.Text;
            phoneLauncher.PhoneNumber = this.Ecn.Text;
            //当号码不为空时，拨号
            if (phoneLauncher.PhoneNumber.Length == 0)
            {
                MessageBox.Show("There is no emergency contact phone number to call!", "Phone", MessageBoxButton.OK);
            }
            else
                phoneLauncher.Show();
        }

效果如下图：

2.2 处理全选消息

        private void Box_GotFocus(object sender, RoutedEventArgs e)
        {
            (sender as TextBox).SelectAll();
        }

效果见下图：

2.3 实现按键消息处理

主要是实现将输入焦点进行传递的功能，要注意最后一个文本框的回车在这里面表示换行，所以我们要去掉最后一个文本框的绑定事件KeyDown。

        private void BoxKeyDown_Event(object sender, KeyEventArgs e)
        {
            if(e.Key == Key.Enter)
            {
                if (sender == this.Ecp)
                    this.Ecn.Focus();
                else if (sender == this.Ecn)
                    this.Pon.Focus();
                else if (sender == this.Pon)
                    this.Pomn.Focus();
                e.Handled = true;
            }
        }