HeartRateMonitorAndroid/MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="HeartRateMonitorAndroid.MainPage"
             BackgroundColor="#F8F9FA"
             Title="心率监测">

    <Grid Padding="20" RowSpacing="20">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>

        <!-- 服务状态指示器 -->
        <Frame Grid.Row="0" BorderColor="#E9ECEF" CornerRadius="15" Padding="15" 
               BackgroundColor="White" HasShadow="True">
            <Grid ColumnSpacing="15">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="Auto"/>
                </Grid.ColumnDefinitions>

                <!-- 状态指示灯 -->
                <Ellipse Grid.Column="0" 
                         x:Name="statusIndicator"
                         Fill="#28A745" 
                         WidthRequest="16" 
                         HeightRequest="16"
                         VerticalOptions="Center"/>

                <!-- 状态文本 -->
                <VerticalStackLayout Grid.Column="1" Spacing="2">
                    <Label x:Name="serviceStatusLabel" 
                           Text="后台服务运行中" 
                           FontSize="16" 
                           FontAttributes="Bold"
                           TextColor="#495057"/>
                    <Label x:Name="connectionStatusLabel" 
                           Text="正在连接心率设备..." 
                           FontSize="14" 
                           TextColor="#6C757D"/>
                </VerticalStackLayout>

                <!-- 数据上传状态 -->
                <Label Grid.Column="2"
                       x:Name="uploadStatusLabel"
                       Text="已连接"
                       FontSize="12"
                       TextColor="#28A745"
                       VerticalOptions="Center"
                       HorizontalOptions="End"/>
            </Grid>
        </Frame>

        <!-- 当前心率显示 -->
        <Frame Grid.Row="1" BorderColor="#E9ECEF" CornerRadius="15" Padding="20" 
               BackgroundColor="White" HasShadow="True">
            <VerticalStackLayout HorizontalOptions="Center" Spacing="5">
                <Label Text="当前心率" 
                       FontSize="16" 
                       TextColor="#6C757D"
                       HorizontalOptions="Center"/>
                <Label x:Name="heartRateLabel" 
                       Text="-- bpm" 
                       FontSize="48" 
                       FontAttributes="Bold"
                       TextColor="#FF4757"
                       HorizontalOptions="Center"/>
                <Label x:Name="lastUpdateLabel"
                       Text="等待数据..."
                       FontSize="12"
                       TextColor="#ADB5BD"
                       HorizontalOptions="Center"/>
            </VerticalStackLayout>
        </Frame>

        <!-- 心率统计信息 -->
        <Grid Grid.Row="2" ColumnSpacing="10">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>

            <!-- 最低心率 -->
            <Frame Grid.Column="0" BorderColor="#E9ECEF" BackgroundColor="#E8F5FE" CornerRadius="12" Padding="15" HasShadow="True">
                <VerticalStackLayout HorizontalOptions="Center" Spacing="3">
                    <Label Text="最低" FontSize="12" TextColor="#2E86DE" FontAttributes="Bold" HorizontalOptions="Center"/>
                    <Label x:Name="minHeartRateLabel" Text="--" FontSize="20" TextColor="#0056B3" FontAttributes="Bold" HorizontalOptions="Center"/>
                    <Label Text="bpm" FontSize="10" TextColor="#2E86DE" HorizontalOptions="Center"/>
                </VerticalStackLayout>
            </Frame>

            <!-- 平均心率 -->
            <Frame Grid.Column="1" BorderColor="#E9ECEF" BackgroundColor="#FFF5F5" CornerRadius="12" Padding="15" HasShadow="True">
                <VerticalStackLayout HorizontalOptions="Center" Spacing="3">
                    <Label Text="平均" FontSize="12" TextColor="#FF4757" FontAttributes="Bold" HorizontalOptions="Center"/>
                    <Label x:Name="avgHeartRateLabel" Text="--" FontSize="20" TextColor="#E01B30" FontAttributes="Bold" HorizontalOptions="Center"/>
                    <Label Text="bpm" FontSize="10" TextColor="#FF4757" HorizontalOptions="Center"/>
                </VerticalStackLayout>
            </Frame>

            <!-- 最高心率 -->
            <Frame Grid.Column="2" BorderColor="#E9ECEF" BackgroundColor="#FFF0E5" CornerRadius="12" Padding="15" HasShadow="True">
                <VerticalStackLayout HorizontalOptions="Center" Spacing="3">
                    <Label Text="最高" FontSize="12" TextColor="#FF8832" FontAttributes="Bold" HorizontalOptions="Center"/>
                    <Label x:Name="maxHeartRateLabel" Text="--" FontSize="20" TextColor="#E65C00" FontAttributes="Bold" HorizontalOptions="Center"/>
                    <Label Text="bpm" FontSize="10" TextColor="#FF8832" HorizontalOptions="Center"/>
                </VerticalStackLayout>
            </Frame>
        </Grid>

        <!-- 心率图表 -->
        <Frame Grid.Row="3" BorderColor="#E9ECEF" CornerRadius="15" Padding="15" 
               BackgroundColor="White" HasShadow="True">
            <Grid>
                <GraphicsView x:Name="heartRateGraphicsView" BackgroundColor="White"/>
                <VerticalStackLayout x:Name="noDataLayout" 
                                   HorizontalOptions="Center" 
                                   VerticalOptions="Center"
                                   IsVisible="True" 
                                   Spacing="10">
                    <Label Text="📊" FontSize="40" HorizontalOptions="Center"/>
                    <Label Text="等待心率数据" 
                           HorizontalOptions="Center" 
                           TextColor="#6C757D" 
                           FontSize="16"/>
                    <Label Text="后台服务将自动连接设备并获取数据" 
                           HorizontalOptions="Center" 
                           TextColor="#ADB5BD" 
                           FontSize="12"
                           HorizontalTextAlignment="Center"/>
                </VerticalStackLayout>
            </Grid>
        </Frame>

        <!-- 会话信息 -->
        <Frame Grid.Row="4" BorderColor="#E9ECEF" CornerRadius="15" Padding="15" 
               BackgroundColor="White" HasShadow="True">
            <Grid ColumnSpacing="20">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>

                <VerticalStackLayout Grid.Column="0" Spacing="3">
                    <Label Text="监测时长" FontSize="12" TextColor="#6C757D" FontAttributes="Bold"/>
                    <Label x:Name="durationLabel" Text="00:00:00" FontSize="16" TextColor="#495057" FontAttributes="Bold"/>
                </VerticalStackLayout>

                <VerticalStackLayout Grid.Column="1" Spacing="3">
                    <Label Text="数据点数" FontSize="12" TextColor="#6C757D" FontAttributes="Bold"/>
                    <Label x:Name="dataPointsLabel" Text="0" FontSize="16" TextColor="#495057" FontAttributes="Bold"/>
                </VerticalStackLayout>
            </Grid>
        </Frame>
    </Grid>
</ContentPage>