在焦点侦听器中更改复合可绘制时，EditText会无限地触发焦点更改事件

Question

我有一个自定义的edittext控件，当它处于焦点并有文本时，右侧有一个清晰的(x)图标。单击清除图标将从textbox中删除文本。不幸的是，当你点击进入textbox时，焦点变化事件无限激发，因为在drawable中更改复合focus change listener似乎会激活两个focus change events，第一个关闭焦点，第二个重点关注。知道如何在没有无限循环的情况下让它工作吗？

这是代码：

public class CustomEditText : EditText {
        private Drawable clearButton;

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

        public CustomEditText (Context context) : base (context) {
            Init ();
        }

        public CustomEditText (Context context, IAttributeSet attrs) : base (context, attrs) {
            Init (attrs);
        }

        public CustomEditText (Context context, IAttributeSet attrs, int defStyle) : base (context, attrs, defStyle) {
            Init (attrs);
        }

        protected void Init (IAttributeSet attrs = null) {
            // Set up clear button
            SetupClearButton ();
            SetupEvents ();
        }

        private void SetupClearButton () {
            clearButton = ContextCompat.GetDrawable (android.App.Application.Context, Resource.Drawable.forms_edit_text_clear_gray);
            clearButton.SetBounds (0, 0, clearButton.IntrinsicWidth, clearButton.IntrinsicHeight);
        }

        private void SetupEvents () {
            // Handle clear button visibility
            this.TextChanged += (sender, e) => {
                if (this.HasFocus)
                    UpdateClearButton ();
            };
            this.FocusChange += (object sender, FocusChangeEventArgs e) => {
                UpdateClearButton (e.HasFocus);// Gets called infinitely
            };

            // Handle clearing the text
            this.Touch += (sender, e) => {
                if (this.GetCompoundDrawables ()[2] != null && 
                    e.Event.Action == MotionEventActions.Up &&
                    e.Event.GetX () > (this.Width - this.PaddingRight - clearButton.IntrinsicWidth)) {
                    this.Text = "";
                    UpdateClearButton ();
                    e.Handled = true;
                } else
                    e.Handled = false;
            };
        }

        private void UpdateClearButton (bool hasFocus = true) {
            var compoundDrawables = this.GetCompoundDrawables ();
            var compoundDrawable = this.Text.Length == 0 || !hasFocus ? null : clearButton;
            if (compoundDrawables[2] != compoundDrawable)
                this.SetCompoundDrawables (compoundDrawables[0], compoundDrawables[1], compoundDrawable, compoundDrawables[3]);
        }
    }

Answer 1

另一答案