c# - 24 小时 TimePicker，带有聚焦和非聚焦事件

Question

我尝试实现 24 小时 Time Picker，如此处 24 Hour TimePicker在 XF 项目中。

但它不会触发 Android 上的 Focus 和 Unfocused 事件。有人实现了吗？

Answer 1

这是一个完整的示例:https://github.com/brminnick/24HourTimePicker

说明

此自定义控件的作者忘记触发 Focused和 Unfocused在 Android 自定义渲染器中。

我们可以通过调用 ElementController.SetValueFromRenderer(VisualElement.IsFocusedPropertyKey, [true/false]); 来触发这些事件来自 Android Custom Renderer when FocusChanged火灾。

此自定义 Android 控件在设置时间后也不会清除焦点，因此我们将添加 ClearFocus()至 OnTimeSet也是。

Xamarin.Forms 2.4 代码

因为示例是用 Xamarin.Forms v2.4 编写的，所以如果您继续使用 Xamarin.Forms v2.4，这里就是答案。

using System;

using Android.App;
using Android.Content;
using Android.Runtime;

using TimePickerDemo.CustomControls;
using TimePickerDemo.Droid;

using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(CustomTimePicker24H), typeof(CustomTimePicker24HRenderer))]
namespace TimePickerDemo.Droid
{
    public class CustomTimePicker24HRenderer : ViewRenderer<Xamarin.Forms.TimePicker, Android.Widget.EditText>, TimePickerDialog.IOnTimeSetListener, IJavaObject, IDisposable
    {
        private TimePickerDialog dialog = null;

        IElementController ElementController => Element as IElementController;

        protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.TimePicker> e)
        {
            base.OnElementChanged(e);
            this.SetNativeControl(new Android.Widget.EditText(Forms.Context));
            this.Control.Click += Control_Click;
            this.Control.Text = DateTime.Now.ToString("HH:mm");
            this.Control.KeyListener = null;
            this.Control.FocusChange += Control_FocusChange;
        }

        void Control_FocusChange(object sender, Android.Views.View.FocusChangeEventArgs e)
        {
            if (e.HasFocus)
            {
                ShowTimePicker();
                ElementController.SetValueFromRenderer(VisualElement.IsFocusedPropertyKey, true);
            }
            else
            {
                ElementController.SetValueFromRenderer(VisualElement.IsFocusedPropertyKey, false);
            }
        }

        void Control_Click(object sender, EventArgs e)
        {
            ShowTimePicker();
        }

        private void ShowTimePicker()
        {
            if (dialog == null)
            {
                dialog = new TimePickerDialog(Forms.Context, this, DateTime.Now.Hour, DateTime.Now.Minute, true);
            }

            dialog.Show();
        }

        public void OnTimeSet(Android.Widget.TimePicker view, int hourOfDay, int minute)
        {
            var time = new TimeSpan(hourOfDay, minute, 0);
            this.Element.SetValue(Xamarin.Forms.TimePicker.TimeProperty, time);

            this.Control.Text = time.ToString(@"hh\:mm");

            this.ClearFocus();
        }
    }
}

Xamarin.Forms 2.5+ 答案

Xamarin.Forms v2.5 已弃用 Forms.Context并且还需要一个重载的构造函数用于自定义渲染器。

替换Forms.Context ，我们需要安装 Plugin.CurrentActivity NuGet Package .

using System;

using Android.App;
using Android.Content;
using Android.Runtime;

using TimePickerDemo.CustomControls;
using TimePickerDemo.Droid;

using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(CustomTimePicker24H), typeof(CustomTimePicker24HRenderer))]
namespace TimePickerDemo.Droid
{
    public class CustomTimePicker24HRenderer : ViewRenderer<Xamarin.Forms.TimePicker, Android.Widget.EditText>, TimePickerDialog.IOnTimeSetListener, IJavaObject, IDisposable
    {
        private TimePickerDialog dialog = null;

        public CustomTimePicker24HRenderer(Context context) : base(context)
        {
            
        }

        Context CurrentContext => Plugin.CurrentActivity.CrossCurrentActivity.Current.Activity;
        IElementController ElementController => Element as IElementController;

        protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.TimePicker> e)
        {
            base.OnElementChanged(e);
            this.SetNativeControl(new Android.Widget.EditText(CurrentContext));
            this.Control.Click += Control_Click;
            this.Control.Text = DateTime.Now.ToString("HH:mm");
            this.Control.KeyListener = null;
            this.Control.FocusChange += Control_FocusChange;
        }

        void Control_FocusChange(object sender, Android.Views.View.FocusChangeEventArgs e)
        {
            if (e.HasFocus)
            {
                ShowTimePicker();
                ElementController.SetValueFromRenderer(VisualElement.IsFocusedPropertyKey, true);
            }
            else
            {
                ElementController.SetValueFromRenderer(VisualElement.IsFocusedPropertyKey, false);
            }
        }

        void Control_Click(object sender, EventArgs e)
        {
            ShowTimePicker();
        }

        private void ShowTimePicker()
        {
            if (dialog == null)
            {
                dialog = new TimePickerDialog(CurrentContext, this, DateTime.Now.Hour, DateTime.Now.Minute, true);
            }

            dialog.Show();
        }

        public void OnTimeSet(Android.Widget.TimePicker view, int hourOfDay, int minute)
        {
            var time = new TimeSpan(hourOfDay, minute, 0);
            this.Element.SetValue(Xamarin.Forms.TimePicker.TimeProperty, time);

            this.Control.Text = time.ToString(@"hh\:mm");

            this.ClearFocus();
        }
    }
}