Xamarin形式的TimePicker，间隔为15分钟

问题描述

我需要在时间选择器中设置15分钟间隔。我已经为iOS做过。但是在Android中，它不起作用。

对于iOS，我使用了以下代码，并且可以正常工作：

public class CustomTimePickerRenderer : TimePickerRenderer
{
    protected override void OnElementChanged(ElementChangedEventArgs<TimePicker> e)
    {
            base.OnElementChanged(e);
            var view = (TimePicker)Element;

        if (view != null)
        {
                var timePicker = (UIDatePicker)Control.InputView;
            timePicker.MinuteInterval = 15;
            }
    }
}

对于Andoroid，我正在尝试以下代码：

public class CustomTimePickerRenderer : TimePickerRenderer
{
    Context _context;

    public CustomTimePickerRenderer(Context context) : base(context)
    {
        _context = context;
    }

    protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.TimePicker> e)
    {
        base.OnElementChanged(e);

        TimePickerDialogIntervals timePickerDlg = new TimePickerDialogIntervals(this.Context,new EventHandler<TimePickerDialogIntervals.TimeSetEventArgs>(UpdateDuration),Element.Time.Hours,Element.Time.Minutes,true);

        var control = new EditText(this.Context);
        control.Focusable = false;
        control.FocusableInTouchMode = false;
        control.Clickable = false;
        control.Click += (sender,ea) => timePickerDlg.Show();
        control.Text = Element.Time.Hours.ToString("00") + ":" + Element.Time.Minutes.ToString("00");

        SetNativeControl(control);
    }

    void UpdateDuration(object sender,Android.App.TimePickerDialog.TimeSetEventArgs e)
    {
        Element.Time = new TimeSpan(e.HourOfDay,e.Minute,0);
        Control.Text = Element.Time.Hours.ToString("00") + ":" + Element.Time.Minutes.ToString("00");
    }
}

public class TimePickerDialogIntervals : TimePickerDialog
{
    public const int TimePickerInterval = 15;
    private bool _ignoreEvent = false;

    public TimePickerDialogIntervals(Context context,EventHandler<TimePickerDialog.TimeSetEventArgs> callBack,int hourOfDay,int minute,bool is24HourView)
        : base(context,(sender,e) => {
            callBack(sender,new TimePickerDialog.TimeSetEventArgs(e.HourOfDay,e.Minute * TimePickerInterval));
        },hourOfDay,minute / TimePickerInterval,is24HourView)
    {
    }

    protected TimePickerDialogIntervals(IntPtr javaReference,JniHandleOwnership transfer) : base(javaReference,transfer)
    {
    }

    public override void SetView(Android.Views.View view)
    {
        SetupMinutePicker(view);
        base.SetView(view);
    }

    void SetupMinutePicker(Android.Views.View view)
    {
        var numberPicker =  FindMinuteNumberPicker(view as ViewGroup);
        if (numberPicker != null)
        {
            numberPicker.MinValue = 0;
            numberPicker.MaxValue = 3;
            numberPicker.SetdisplayedValues(new String[] { "00","15","30","45" });
        }
    }

    protected override void OnCreate(Android.OS.Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        GetButton((int)DialogButtonType.Negative).Visibility = Android.Views.ViewStates.Gone;
        this.SetCanceledOnTouchOutside(false);
    }

    private NumberPicker FindMinuteNumberPicker(ViewGroup viewGroup)
    {
        for (var i = 0; i < viewGroup.ChildCount; i++)
        {
            var child = viewGroup.GetChildAt(i);
            var numberPicker = child as NumberPicker;
            if (numberPicker != null)
            {
                if (numberPicker.MaxValue == 59)
                {
                    return numberPicker;
                }
            }

            var childViewGroup = child as ViewGroup;
            if (childViewGroup != null)
            {
                var childResult = FindMinuteNumberPicker(childViewGroup);
                if (childResult != null)
                    return childResult;
            }
        }

        return null;
    }
}

但是Android代码无法正常工作。我认为问题出在SetupMinutePicker方法中的数字选择器上。我在数字选择器中得到了空值。 请让我知道如何解决此数字选择器问题，或者是否有其他替代方法来设置15分钟的时间选择器。

解决方法

我找到了适用于Android的解决方法。先前的覆盖INSERT INTO My_Table (COMMON_ID,COMMON_LIMIT_IDENTITY,COMMON_CLASS_ID,COMMON_ASSET_TYPE) SELECT NEWID(),'USER' FROM My_Table WHERE COMMON_ASSET_TYPE = 'ASSET' 方法现在无法获取SetView(...)，在这里我们可以按如下方式更改覆盖NumberPicker方法中的分钟间隔：

OnTimeChanged

完整的android渲染器代码如下：

public override void OnTimeChanged(Android.Widget.TimePicker view,int hourOfDay,int minute)
{
    if (_ignoreEvent) return;

    if (minute % TimePickerInterval != 0)
    {
        int minuteFloor = minute - (minute % TimePickerInterval);
        minute = minuteFloor + (minute == minuteFloor + 1 ? TimePickerInterval : 0);
        if (minute == 60)
            minute = 0;
        _ignoreEvent = true;
        view.CurrentMinute = (Java.Lang.Integer)minute;
        _ignoreEvent = false;
    }
}

效果：

,

对我来说，Junior Jiang 的解决方案在 Xamarin.Forms 5.0 中不再适用。这样做的原因是基础渲染器总是调用自己的 TimePickerDialog。幸运的是，您可以覆盖必要的方法。

我还改变了分钟跳转到最接近当前位置的下一个间隔的行为。我认为这比完全拉到下一个间隔要快得多。分钟的某些特定值也有轻微的计算错误，导致指针闪烁。

public class IntervalTimePickerRenderer : TimePickerRenderer
{
    private Context _context;

    public IntervalTimePickerRenderer(Context context) : base(context)
    {
        _context = context;
    }

    protected override TimePickerDialog CreateTimePickerDialog(int hours,int minutes)
    {
        return new TimePickerDialogIntervals(
            Context,UpdateDuration,hours,minutes,DateFormat.Is24HourFormat(_context));
    }

    void UpdateDuration(object sender,TimePickerDialog.TimeSetEventArgs e)
    {
        Element.Time = new TimeSpan(e.HourOfDay,e.Minute,0);
        Control.Text = Element.Time.Hours.ToString("00") + ":" + Element.Time.Minutes.ToString("00");

        Element.Unfocus();
    }
}

public class TimePickerDialogIntervals : TimePickerDialog
{
    public const int TimePickerInterval = 15;
    private bool _ignoreEvent = false;

    public TimePickerDialogIntervals(
        Context context,EventHandler<TimeSetEventArgs> callBack,int minute,bool is24HourView)
        : base(context,(sender,e) =>
              {
                  callBack(sender,new TimePickerDialog.TimeSetEventArgs(e.HourOfDay,e.Minute));
              },hourOfDay,minute,is24HourView)
    {
    }

    public override void OnTimeChanged(Android.Widget.TimePicker view,int minute)
    {
        base.OnTimeChanged(view,minute);

        if (_ignoreEvent) return;

        if (minute % TimePickerInterval != 0)
        {
            float minuteFactor = (float)minute / TimePickerInterval;
            int intervalFactor = (int)Math.Round(minuteFactor,0);

            minute = intervalFactor * TimePickerInterval;
            
            if (minute == 60)
            {
                minute = 0;
            }

            _ignoreEvent = true;
            view.Minute = minute;
            _ignoreEvent = false;
        }
    }
}