如何在Xamarin.Forms中单击按钮时更改自定义条目浮动标签的颜色

Question

我使用此uri https://github.com/AlejandroRuiz/FloatingTextEntry

的自定义渲染器创建了一个带有浮动标签的自定义 条目 字段

我需要在按钮点击上更改条目下划线颜色和占位符颜色。

自定义输入代码：

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using Xamarin.Forms;

namespace BloodTrace.CustomControls
{
    public class XfxEntry : Entry
    {
        public static readonly BindableProperty ErrorTextProperty = BindableProperty.Create(nameof(ErrorText),
            typeof(string),
            typeof(XfxEntry),
            default(string), propertyChanged: OnErrorTextChangedInternal);

        public static readonly BindableProperty FloatingHintEnabledProperty = BindableProperty.Create(nameof(FloatingHintEnabled),
            typeof(bool),
            typeof(XfxEntry),
            true);

        public static readonly BindableProperty ActivePlaceholderColorProperty = BindableProperty.Create(nameof(ActivePlaceholderColor),
            typeof(Color),
            typeof(XfxEntry),
            Color.Accent);

        /// <summary>
        /// ActivePlaceholderColor summary. This is a bindable property.
        /// </summary>
        public Color ActivePlaceholderColor
        {
            get { return (Color)GetValue(ActivePlaceholderColorProperty); }
            set { SetValue(ActivePlaceholderColorProperty, value); }
        }
        public Color ErrorPlaceholderColor
        {
            get { return (Color)GetValue(ErrorPlaceholderColorProperty); }
            set { SetValue(ErrorPlaceholderColorProperty, value); }
        }
        public static readonly BindableProperty ErrorPlaceholderColorProperty = BindableProperty.Create(nameof(ErrorPlaceholderColor),
           typeof(Color),
           typeof(XfxEntry),
           Color.Green);
        /// <summary>
        /// <c>true</c> to float the hint into a label, otherwise <c>false</c>. This is a bindable property.
        /// </summary>
        public bool FloatingHintEnabled
        {
            get { return (bool)GetValue(FloatingHintEnabledProperty); }
            set { SetValue(FloatingHintEnabledProperty, value); }
        }

        /// <summary>
        /// Gets or Sets whether or not the Error Style is 'Underline' or 'None'
        /// </summary>
        public ErrorDisplay ErrorDisplay { get; set; } = ErrorDisplay.None;
        public bool IsErrorPlaceholderColorChange { get; set; } = false;
        /// <summary>
        ///    Error text for the entry. An empty string removes the error. This is a bindable property.
        /// </summary>
        public string ErrorText
        {
            get { return (string)GetValue(ErrorTextProperty); }
            set { SetValue(ErrorTextProperty, value); }
        }

        /// <summary>
        /// Raised when the value of the error text changes
        /// </summary>
        public event EventHandler<TextChangedEventArgs> ErrorTextChanged;

        private static void OnErrorTextChangedInternal(BindableObject bindable, object oldvalue, object newvalue)
        {
            var materialEntry = (XfxEntry)bindable;
            materialEntry.OnErrorTextChanged(bindable, oldvalue, newvalue);
            materialEntry.ErrorTextChanged?.Invoke(materialEntry, new TextChangedEventArgs((string)oldvalue, (string)newvalue));
        }

        protected virtual void OnErrorTextChanged(BindableObject bindable, object oldvalue, object newvalue) { }
       

    }

    public enum ErrorDisplay
    {
        Underline,
        None
    }
}

Android Renderer：-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;

using BloodTrace;
using BloodTrace.Droid.Renderer;
using Application = Android.App.Application;
using Color = Xamarin.Forms.Color;
using AColor = Android.Graphics.Color;
using FormsAppCompat = Xamarin.Forms.Platform.Android.AppCompat;
using BloodTrace.CustomControls;
using Android.Support.Design.Widget;
using Android.Text;
using Xamarin.Forms;
using Android.Content.Res;
using Android.Views.InputMethods;
using Java.Lang;
using Android.Support.V7.Widget;
using Android.Util;
using Xamarin.Forms.Platform.Android;
using System.ComponentModel;
using Android.Text.Method;
using Android.Support.V4.View;
using BloodTrace.Droid.Extensions;
using BloodTraceSharedProject.Extensions;

[assembly: ExportRenderer(typeof(XfxEntry), typeof(XfxEntryRendererDroid))]
namespace BloodTrace.Droid.Renderer
{
    public class XfxEntryRendererDroid : FormsAppCompat.ViewRenderer<XfxEntry, TextInputLayout>,
        ITextWatcher,
        TextView.IOnEditorActionListener
    {
        private bool _hasFocus;
        private ColorStateList _defaultTextColor;

        public XfxEntryRendererDroid(Context context) : base(context)
        {
            AutoPackage = false;
        }

        protected EditText EditText => Control.EditText;

        public bool OnEditorAction(TextView v, ImeAction actionId, KeyEvent e)
        {
            if ((actionId == ImeAction.Done) || ((actionId == ImeAction.ImeNull) && (e.KeyCode == Keycode.Enter)))
            {
                Control.ClearFocus();
                HideKeyboard();
                ((IEntryController)Element).SendCompleted();
            }
            return true;
        }

        public virtual void AfterTextChanged(IEditable s)
        {
        }

        public virtual void BeforeTextChanged(ICharSequence s, int start, int count, int after)
        {
        }

        public virtual void OnTextChanged(ICharSequence s, int start, int before, int count)
        {
            if (string.IsNullOrWhiteSpace(Element.Text) && (s.Length() == 0)) return;
            ((IElementController)Element).SetValueFromRenderer(Entry.TextProperty, s.ToString());
        }

        protected override TextInputLayout CreateNativeControl()
        {
            var textInputLayout = new TextInputLayout(Context);
            var editText = new AppCompatEditText(Context)
            {
                SupportBackgroundTintList = ColorStateList.ValueOf(GetPlaceholderColor())
            };
            editText.SetTextSize(ComplexUnitType.Sp, (float)Element.FontSize);
            textInputLayout.AddView(editText);
            return textInputLayout;
        }

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

            if (e.OldElement != null)
                if (Control != null)
                    EditText.FocusChange -= ControlOnFocusChange;

            if (e.NewElement != null)
            {
                var ctrl = CreateNativeControl();
                SetNativeControl(ctrl);

                if (!string.IsNullOrWhiteSpace(Element.AutomationId))
                    EditText.ContentDescription = Element.AutomationId;

                _defaultTextColor = EditText.TextColors;

                Focusable = true;
                EditText.ShowSoftInputOnFocus = true;

                // Subscribe
                EditText.FocusChange += ControlOnFocusChange;
                EditText.AddTextChangedListener(this);
                EditText.SetOnEditorActionListener(this);
                EditText.ImeOptions = ImeAction.Done;

                SetText();
                SetHintText();
                SetErrorText();
                SetFontAttributesSizeAndFamily();
                SetInputType();
                SetTextColor();
                SetHorizontalTextAlignment();
                SetFloatingHintEnabled();
                SetIsEnabled();
                SetErrorDisplay();
                SetLabelAndUnderlineColor();
            }
        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);

            if (e.PropertyName == Entry.PlaceholderProperty.PropertyName)
                SetHintText();
            else if (e.PropertyName == XfxEntry.ErrorTextProperty.PropertyName)
                SetErrorText();
            else if (e.PropertyName == Entry.IsPasswordProperty.PropertyName ||
                e.PropertyName == InputView.KeyboardProperty.PropertyName)
                SetInputType();
            else if (e.PropertyName == Entry.TextProperty.PropertyName)
                SetText();
            else if (e.PropertyName == Entry.HorizontalTextAlignmentProperty.PropertyName)
                SetHorizontalTextAlignment();
            else if (e.PropertyName == XfxEntry.FloatingHintEnabledProperty.PropertyName)
                SetFloatingHintEnabled();
            else if (e.PropertyName == VisualElement.IsEnabledProperty.PropertyName)
                SetIsEnabled();
            else if ((e.PropertyName == Entry.FontAttributesProperty.PropertyName) ||
                     (e.PropertyName == Entry.FontFamilyProperty.PropertyName) ||
                     (e.PropertyName == Entry.FontSizeProperty.PropertyName))
                SetFontAttributesSizeAndFamily();
            else if (e.PropertyName == XfxEntry.ActivePlaceholderColorProperty.PropertyName ||
                     e.PropertyName == Entry.PlaceholderColorProperty.PropertyName)
                SetLabelAndUnderlineColor();
            else if (e.PropertyName == Entry.TextColorProperty.PropertyName)
                SetTextColor();
        }

        private void ControlOnFocusChange(object sender, FocusChangeEventArgs args)
        {
            _hasFocus = args.HasFocus;
            if (_hasFocus)
            {
                var manager = (InputMethodManager)Application.Context.GetSystemService(Context.InputMethodService);

                EditText.PostDelayed(() =>
                {
                    EditText.RequestFocus();
                    manager.ShowSoftInput(EditText, 0);
                },
                    100);
            }

            var isFocusedPropertyKey = Element.GetInternalField<BindablePropertyKey>("IsFocusedPropertyKey");
            ((IElementController)Element).SetValueFromRenderer(isFocusedPropertyKey, _hasFocus);

            //This will change floating label entry  SetUnderlineColor >>>>  SetUnderlineColor color basedon focus or non focus
            SetUnderlineColor(_hasFocus ? GetActivePlaceholderColor() : GetPlaceholderColor());
        }

        
        protected AColor GetPlaceholderColor() => Element.PlaceholderColor.ToAndroid(Color.FromHex("#80000000"));

        private AColor GetActivePlaceholderColor() => Element.ActivePlaceholderColor.ToAndroid(global::Android.Resource.Attribute.ColorAccent, Context);

        protected virtual void SetLabelAndUnderlineColor()
        {
            var defaultColor = GetPlaceholderColor();
            var activeColor = GetActivePlaceholderColor();

            SetHintLabelDefaultColor(defaultColor);
            SetHintLabelActiveColor(activeColor);
            SetUnderlineColor(_hasFocus ? activeColor : defaultColor);
        }

        //This will change entry under line color 
        private void SetUnderlineColor(AColor color)
        {
            var element = (ITintableBackgroundView)EditText;
            element.SupportBackgroundTintList = ColorStateList.ValueOf(color);
        }

        private void SetHintLabelActiveColor(AColor color)
        {
            var hintText = Control.Class.GetDeclaredField("mFocusedTextColor");
            hintText.Accessible = true;
            hintText.Set(Control, new ColorStateList(new int[][] { new[] { 0 } }, new int[] { color }));
        }

        private void SetHintLabelDefaultColor(AColor color)
        {
            var hint = Control.Class.GetDeclaredField("mDefaultTextColor");
            hint.Accessible = true;
            hint.Set(Control, new ColorStateList(new int[][] { new[] { 0 } }, new int[] { color }));
        }

        private void SetText()
        {
            if (EditText.Text != Element.Text)
            {
                EditText.Text = Element.Text;
                if (EditText.IsFocused)
                    EditText.SetSelection(EditText.Text.Length);
            }
        }

        private void SetHintText()
        {
            Control.Hint = Element.Placeholder;
        }

        private void SetTextColor()
        {
            if (Element.TextColor == Color.Default)
            {
                EditText.SetTextColor(_defaultTextColor);
            }
            else
            {
                EditText.SetTextColor(Element.TextColor.ToAndroid());
            }
        }

        private void SetHorizontalTextAlignment()
        {
            switch (Element.HorizontalTextAlignment)
            {
                case Xamarin.Forms.TextAlignment.Center:
                    EditText.Gravity = GravityFlags.CenterHorizontal;
                    break;
                case Xamarin.Forms.TextAlignment.End:
                    EditText.Gravity = GravityFlags.Right;
                    break;
                default:
                    EditText.Gravity = GravityFlags.Left;
                    break;
            }
        }

        public void SetFloatingHintEnabled()
        {
            Control.HintEnabled = Element.FloatingHintEnabled;
            Control.HintAnimationEnabled = Element.FloatingHintEnabled;
            SetFontAttributesSizeAndFamily();
        }

        public void SetErrorDisplay()
        {
            switch (Element.ErrorDisplay)
            {
                case ErrorDisplay.None:
                    Control.ErrorEnabled = false;
                    break;
                case ErrorDisplay.Underline:
                    Control.ErrorEnabled = true;
                    break;
            }
        }

        protected void HideKeyboard()
        {
            var manager = (InputMethodManager)Application.Context.GetSystemService(Context.InputMethodService);
            manager.HideSoftInputFromWindow(EditText.WindowToken, 0);
        }


        //here we can set entry floating label >>> input text  size
        private void SetFontAttributesSizeAndFamily()
        {
            EditText.Typeface = Control.Typeface = Element.ToTypeface();
            EditText.SetTextSize(ComplexUnitType.Sp, (float)Element.FontSize);
            //var a = (float)Element.FontSize; //18
        }

        private void SetErrorText()
        {
            Control.Error = !string.IsNullOrEmpty(Element.ErrorText) ? Element.ErrorText : null;
        }
        private void SetIsEnabled()
        {
            EditText.Enabled = Element.IsEnabled;
        }

        private void SetInputType()
        {
            EditText.InputType = Element.Keyboard.ToInputType();
            if (Element.IsPassword && (EditText.InputType & InputTypes.ClassText) == InputTypes.ClassText)
            {
                EditText.TransformationMethod = new PasswordTransformationMethod();
                EditText.InputType = EditText.InputType | InputTypes.TextVariationPassword;
            }
            if (Element.IsPassword && (EditText.InputType & InputTypes.ClassNumber) == InputTypes.ClassNumber)
            {
                EditText.TransformationMethod = new PasswordTransformationMethod();
                EditText.InputType = EditText.InputType | InputTypes.NumberVariationPassword;
            }
        }

        
    }
}

XML：-

<xfx:XfxEntry x:Name="EntPassword"  Placeholder="Password" IsPassword="True" Focused="EntPassword_Focused"></xfx:XfxEntry>
<Button Text="Sign Up" BackgroundColor="#C62729" TextColor="White" x:Name="BtnSignUp" Clicked="BtnSignUp_Clicked"  ></Button>

请帮助。

预先感谢