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Xamarin.Forms DualScreenInfo 協助程序類別

DualScreenInfo 類別可讓您決定檢視所在的窗格、窗格大小、裝置方向、鉸鏈角度等。

設定 DualScreenInfo

請遵循下列指示,在您的應用程式中建立雙螢幕設定:

  1. 請遵循開始使用的指示來新增 NuGet 並設定 Android MainActivity 類別。
  2. 將 新增 using Xamarin.Forms.DualScreen; 至您的類別檔案。
  3. 在您的應用程式中使用類別 DualScreenInfo.Current

屬性

  • 當跨越兩個螢幕時,SpanningBounds 會傳回兩個矩形,表示每個可見區域的界限。 如果未跨越視窗,則會傳回空陣列。
  • HingeBounds 表示螢幕上的鉸鏈位置。
  • IsLandscape:指出裝置是否為橫向。 因為在應用程式跨越兩個螢幕時,原生方向 API 並不會正確回報方向,所以這會非常有幫助。
  • SpanMode:指出版面配置處於直向、橫向或單一窗格模式。

此外,事件會在 PropertyChanged 任何屬性變更時引發,而 HingeAngleChanged 事件會在轉軸角度變更時引發。

Android 和 UWP 上的輪詢轉軸角度

從 Android 和 UWP 平台專案存取 DualScreenInfo 時,可以使用下列方法:

  • GetHingeAngleAsync:擷取裝置鉸鏈的目前角度。 使用模擬器時,可以藉由修改壓力感應器來設定 HingeAngle。

這個方法可以從Android和UWP上的自定義轉譯器叫用。 下列程式代碼顯示Android自定義轉譯器範例:

public class HingeAngleLabelRenderer : Xamarin.Forms.Platform.Android.FastRenderers.LabelRenderer
{
    System.Timers.Timer _hingeTimer;
    public HingeAngleLabelRenderer(Context context) : base(context)
    {
    }

    async void OnTimerElapsed(object sender, System.Timers.ElapsedEventArgs e)
    {
        if (_hingeTimer == null)
            return;

        _hingeTimer.Stop();
        var hingeAngle = await DualScreenInfo.Current.GetHingeAngleAsync();

        Device.BeginInvokeOnMainThread(() =>
        {
            if (_hingeTimer != null)
                Element.Text = hingeAngle.ToString();
        });

        if (_hingeTimer != null)
            _hingeTimer.Start();
    }

    protected override void OnElementChanged(ElementChangedEventArgs<Label> e)
    {
        base.OnElementChanged(e);

        if (_hingeTimer == null)
        {
            _hingeTimer = new System.Timers.Timer(100);
            _hingeTimer.Elapsed += OnTimerElapsed;
            _hingeTimer.Start();
        }
    }

    protected override void Dispose(bool disposing)
    {
        if (_hingeTimer != null)
        {
            _hingeTimer.Elapsed -= OnTimerElapsed;
            _hingeTimer.Stop();
            _hingeTimer = null;
        }

        base.Dispose(disposing);
    }
}

在您的應用程式視窗存取 DualScreenInfo

下列程式碼示範如何在您的應用程式視窗存取 DualScreenInfo

DualScreenInfo currentWindow = DualScreenInfo.Current;

// Retrieve absolute position of the hinge on the screen
var hingeBounds = currentWindow.HingeBounds;

// check if app window is spanned across two screens
if(currentWindow.SpanMode == TwoPaneViewMode.SinglePane)
{
    // window is only on one screen
}
else if(currentWindow.SpanMode == TwoPaneViewMode.Tall)
{
    // window is spanned across two screens and oriented top-bottom
}
else if(currentWindow.SpanMode == TwoPaneViewMode.Wide)
{
    // window is spanned across two screens and oriented side-by-side
}

// Detect if any of the properties on DualScreenInfo change.
// This is useful to detect if the app window gets spanned
// across two screens or put on only one  
currentWindow.PropertyChanged += OnDualScreenInfoChanged;

將 DualScreenInfo 套用至版面配置

DualScreenInfo 類別包含一個可採用版面配置的建構函式,並會提供您裝置上兩個螢幕相對版面配置的相關資訊:

<Grid x:Name="grid" ColumnSpacing="0">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="{Binding Column1Width}" />
        <ColumnDefinition Width="{Binding Column2Width}" />
        <ColumnDefinition Width="{Binding Column3Width}" />
    </Grid.ColumnDefinitions>
    <Label FontSize="Large"
           VerticalOptions="Center"
           HorizontalOptions="End"
           Text="I should be on the left side of the hinge" />
    <Label FontSize="Large"
           VerticalOptions="Center"
           HorizontalOptions="Start"
           Grid.Column="2"
           Text="I should be on the right side of the hinge" />
</Grid>
public partial class GridUsingDualScreenInfo : ContentPage
{
    public DualScreenInfo DualScreenInfo { get; }
    public double Column1Width { get; set; }
    public double Column2Width { get; set; }
    public double Column3Width { get; set; }

    public GridUsingDualScreenInfo()
    {
        InitializeComponent();
        DualScreenInfo = new DualScreenInfo(grid);
        BindingContext = this;
    }

    protected override void OnAppearing()
    {
        base.OnAppearing();
        DualScreenInfo.PropertyChanged += OnInfoPropertyChanged;
        UpdateColumns();
    }

    protected override void OnDisappearing()
    {
        base.OnDisappearing();
        DualScreenInfo.PropertyChanged -= OnInfoPropertyChanged;
    }

    void UpdateColumns()
    {
        // Check if grid is on two screens
        if (DualScreenInfo.SpanningBounds.Length > 0)
        {
            // set the width of the first column to the width of the layout
            // that's on the left screen
            Column1Width = DualScreenInfo.SpanningBounds[0].Width;

            // set the middle column to the width of the hinge
            Column2Width = DualScreenInfo.HingeBounds.Width;

            // set the width of the third column to the width of the layout
            // that's on the right screen
            Column3Width = DualScreenInfo.SpanningBounds[1].Width;
        }
        else
        {
            Column1Width = 100;
            Column2Width = 0;
            Column3Width = 100;
        }

        OnPropertyChanged(nameof(Column1Width));
        OnPropertyChanged(nameof(Column2Width));
        OnPropertyChanged(nameof(Column3Width));

    }

    void OnInfoPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        UpdateColumns();
    }
}

下列螢幕擷取畫面顯示產生的版面配置:

在兩個螢幕上定位格線