Xamarin Android：自定义渲染器的自定义键盘存在问题-出现在控件下方，按键无法按下等

问题描述

我正在创建具有自定义键盘的自定义控件。我遇到了几个问题。

我正在使用Visual Studio Community 2019，并且正在使用Android_Accelerated_x86_Oreo（Android 8.1 API-27）作为我的Android模拟器。

总之，

我需要对Entry进行不同的样式设置，因此我从中创建一个派生类，称为TextBoxEntry。

我在MainPage.cs中以编程方式创建了所有控件，因此MainPage.xaml为空白（差不多）。

Android专用代码（即渲染器）被塞入MainActivity.cs。

最后，自定义键盘在Resources / xml / keyboard.xml下定义。

我无法解决这些问题（已解决5个问题中的3个）：

为什么自定义渲染器的自定义键盘会出现在控件下方？
出现键盘时，我需要获取其高度，以便可以相应地修改scrollview尺寸。不幸的是，在ControlOnFocusChanged（）[EditText.FocusChange事件处理程序]中执行此操作不起作用，因为在该时间点上，键盘仍未显示，因此其高度为0。或者我应该在其中进行操作其他事件吗？ 应改用ViewTreeObserver.IOnGlobalLayoutListener。
键盘上的键不可按下。有时，键盘会隐藏起来。我想我按这些键时，实际输入会失去焦点。无论如何，我实际上在哪里出错？
scrollview的最后一列以及最后一行的TextBoxEntries被剪掉。再说一次，我不知道出了什么问题。 通过将“ margin”设置为1可以解决此问题。
在ControlOnFocusChange（）内，a_height提供1280，而b_height提供342。scrollview占据整个屏幕的一半以上，但是其高度远非整个屏幕的一半。这两个以不同的单位显示吗？ 根据Find our the default height of the controls in Xamarin Forms，似乎两个高地都使用不同的单位...好吧，可以通过一些转换来解决。

因此，这是所有相关文件的内容：

MainPage.xaml：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="CustomKeyboard.MainPage"/>

MainPage.xaml.cs：

using Xamarin.Forms;

namespace CustomKeyboard
{
    public class TextBoxEntry : Entry
    {
        public ScrollView ScrollView { get; set; } = null; // So that I Could easily get its reference and work on it...
    }
    public partial class MainPage : ContentPage
    {
        AbsoluteLayout layout = null;
        ScrollView scrollview = null;
        Grid grid = null;

        public MainPage()
        {
            InitializeComponent();
            BuildControls();
            BuildTextBoxes();
        }
        private void BuildControls()
        {
            layout = new AbsoluteLayout();
            scrollview = new ScrollView();
            grid = new Grid();
            layout.Children.Add(scrollview,new Rectangle(0.5d,0d,0.95d,0.85d),AbsoluteLayoutFlags.All);
            scrollview.BackgroundColor = Color.Yellow;
            scrollview.Padding = 5;
            scrollview.Content = grid;
            Content = layout;
        }
        private void BuildTextBoxes()
        {
            for (var i = 0; i < 50; ++i)
            {
                if (i % 5 == 0)
                {
                    var l = new Label()
                    {
                        Text = (i / 5).ToString(),HorizontalTextAlignment = TextAlignment.Center,VerticalTextAlignment = TextAlignment.Center,};
                    grid.Children.Add(l,i / 5);
                }
                else
                {
                    var r = i / 5;
                    var c = i % 5;
                    var e = new TextBoxEntry();
                    e.Margin = 1; // THIS SOLVES ISSUE 4
                    e.ScrollView = scrollview;
                    grid.Children.Add(e,c,r);
                }
            }
        }
    }
}

MainActivity.cs：

using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.Graphics;
using Android.Graphics.Drawables;
using Android.InputMethodServices;
using Android.OS;
using Android.Support.Design.Widget;
using Android.Views;
using Android.Widget;

using java.lang;

using System.Threading.Tasks;

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

using CustomKeyboard;
using CustomKeyboard.Droid;

[assembly: ExportRenderer(typeof(TextBoxEntry),typeof(TextBoxEntryRenderer))]

namespace CustomKeyboard.Droid
{
    [Activity(
        Label = "CustomKeyboard",Icon = "@mipmap/icon",Theme = "@style/MainTheme",MainLauncher = true,ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation
    )]

    public class MainActivity : FormsAppCompatActivity
    {
        internal static MainActivity Instance { get; private set; }
        protected override void OnCreate(Bundle savedInstanceState)
        {
            Instance = this;

            base.OnCreate(savedInstanceState);

            Xamarin.Essentials.Platform.Init(this,savedInstanceState);
            Forms.Init(this,savedInstanceState);
            LoadApplication(new App());
        }
    }

    public class TextBoxEntryRenderer : VieWrenderer<TextBoxEntry,TextInputLayout>
    {
        public KeyboardView mKeyboardView;
        ViewGroup activityRootView;
        protected EditText editText => Control.EditText;

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

        protected override TextInputLayout CreateNativeControl()
        {
            #region Add keyboard
            var activity = MainActivity.Instance as Activity;
            activity.Window.SetSoftInputMode(SoftInput.StatealwaysHidden);

            var rootView = activity.Window.DecorView.FindViewById(Android.Resource.Id.Content);
            activityRootView = ((ViewGroup)rootView).GetChildAt(0) as ViewGroup;

            mKeyboardView = new KeyboardView(MainActivity.Instance,null);
            mKeyboardView.PreviewEnabled = false; //Removes magnified key popups on key press
            mKeyboardView.Visibility = ViewStates.Gone;
            mKeyboardView.Keyboard = new Android.InputMethodServices.Keyboard(Context,Resource.Xml.keyboard);
            mKeyboardView.Key += (sender,e) =>
            {
                long eventTime = JavaSystem.CurrentTimeMillis();
                dispatchKeyEvent(new KeyEvent(eventTime,eventTime,KeyEventActions.Down,e.PrimaryCode,KeyEventFlags.softKeyboard | KeyEventFlags.KeepTouchMode));

                Task.Delay(1);
            };
            Android.Widget.RelativeLayout.LayoutParams layoutParams =
                new Android.Widget.RelativeLayout.LayoutParams(LayoutParams.MatchParent,LayoutParams.WrapContent); // or wrap_content
            layoutParams.AddRule(LayoutRules.AlignParentBottom);
            activityRootView.AddView(mKeyboardView,layoutParams);
            #endregion

            var _editText = new EditText(Context);
            _editText.SetTextColor(Android.Graphics.Color.Black);
            var textInputLayout = new TextInputLayout(Context);
            textInputLayout.AddView(_editText);
            return textInputLayout;
        }
        protected override void OnElementChanged(ElementChangedEventArgs<TextBoxEntry> e)
        {
            base.OnElementChanged(e);
            if (e.OldElement != null && Control != null) editText.FocusChange -= ControlOnFocusChange;
            if (e.NewElement != null)
            {
                SetNativeControl(CreateNativeControl());
                editText.ShowSoftInputOnFocus = false;
                editText.FocusChange += ControlOnFocusChange;
                editText.SetPadding(20,20,0);
                editText.SetTextSize(Android.Util.ComplexUnitType.Px,32);
                editText.TextChanged += (source,args) => { };
            }
            if (Control != null)
            {
                GradientDrawable gd = new GradientDrawable();
                gd.SetColor(Android.Graphics.Color.Transparent);
                Control.SetBackground(gd);
                editText.Background = null; // Remove underline.
                var shape = new ShapeDrawable(new Android.Graphics.Drawables.Shapes.RectShape());
                shape.Paint.Color = Xamarin.Forms.Color.Gray.ToAndroid();
                shape.Paint.SetStyle(Paint.Style.stroke);
                Control.Background = shape;
            }
        }
        private void ControlOnFocusChange(object sender,FocusChangeEventArgs args)
        {
            if (args.HasFocus)
            {
                editText.Post(() =>
                {
                    editText.RequestFocus();
                    if (mKeyboardView.Visibility == ViewStates.Gone) mKeyboardView.Visibility = ViewStates.Visible;

                    // Wanna resize scrollview,but Couldn't get necessary info...!
                    var devicedisplayInfo = Devicedisplay.MaindisplayInfo;
                    var a_height = devicedisplayInfo.Height;
                    var b_height = Element.ScrollView.Height;
                    var c_height = mKeyboardView.Height;
                });
            }
            else
            {
                // Hide keyboard
                mKeyboardView.Visibility = ViewStates.Gone;
            }
        }
    }
}

最后，资源/xml/keyboard.xml：

<Keyboard xmlns:android="http://schemas.android.com/apk/res/android"
    android:keyWidth="25%p" android:horizontalGap="0px"
    android:verticalGap="0px" android:keyHeight="27dip">

  <Row>
    <Key android:codes="8"  android:keyLabel="1" android:keyHeight="54dip" android:keyEdgeFlags="left" />
    <Key android:codes="9"  android:keyLabel="2" android:keyHeight="54dip" />
    <Key android:codes="10" android:keyLabel="3" android:keyHeight="54dip" />
    <Key android:codes="81" android:keyLabel="+" android:keyHeight="81dip" android:keyEdgeFlags="right" />
  </Row>
  <Row></Row>
  <Row>
    <Key android:codes="11" android:keyLabel="4" android:keyHeight="54dip" android:keyEdgeFlags="left" />
    <Key android:codes="12" android:keyLabel="5" android:keyHeight="54dip" />
    <Key android:codes="13" android:keyLabel="6" android:keyHeight="54dip" />
  </Row>
  <Row>
    <Key android:codes="66" android:keyLabel="RET" android:keyHeight="81dip" android:horizontalGap="75%p" android:keyEdgeFlags="right" />
  </Row>
  <Row>
    <Key android:codes="14" android:keyLabel="7" android:keyHeight="54dip" android:keyEdgeFlags="left" />
    <Key android:codes="15" android:keyLabel="8" android:keyHeight="54dip" />
    <Key android:codes="16" android:keyLabel="9" android:keyHeight="54dip" />
  </Row>
  <Row></Row>
  <Row>
    <Key android:codes="17" android:keyLabel="*" android:keyHeight="54dip" android:keyEdgeFlags="left" />
    <Key android:codes="7"  android:keyLabel="0" android:keyHeight="54dip" />
    <Key android:codes="18" android:keyLabel="#" android:keyHeight="54dip" />
    <Key android:codes="67" android:keyLabel="DEL" android:keyHeight="54dip" android:keyEdgeFlags="right" />
  </Row>
  <Row></Row>

</Keyboard>

解决方法

为什么自定义渲染器的自定义键盘出现在控件下方？

将alignParentBottom属性设置为true，以使我们的键盘从屏幕的底部可见。

android:layout_alignParentBottom="true"

键盘上的键不可按下。有时，键盘会隐藏起来。我想我按这些键时，实际输入会失去焦点。无论如何，我实际上在哪里出错？

为我们的键可以具有的两个状态定义一个状态选择器：正常（不按）和按true或false按下。

您可以从GitHub下载源文件。 https://github.com/WendyZang/CustomKeyboardXamarinForms

android android c#c#custom-keyboard custom-renderer xamarin xamarin