[Android] [TextBox] fix a bug which cause cannot call out the soft keyboard again after closing it (#15603)

* [Android] fix a bug which cause closing soft keyboard does not clear focus on TextBox, which makes clicking on the TextBox cannot call out the soft keyboard again

* change way to show soft keyboard

* add new api

---------

Co-authored-by: Max Katz <maxkatz6@outlook.com>

src/Avalonia.Base/Input/TextInput/TextInputMethodClient.cs

@@ -71,6 +71,8 @@ namespace Avalonia.Input.TextInput
         {
             SetPreeditText(preeditText);
         }
+
+        public virtual void ShowInputPanel() { }
         
         protected virtual void RaiseTextViewVisualChanged()
         {

src/Avalonia.Controls/TextBox.cs

@@ -1724,6 +1724,8 @@ namespace Avalonia.Controls
 
             if (e.Pointer.Type != PointerType.Mouse && !_isDoubleTapped)
             {
+                _imClient.ShowInputPanel();
+
                 var text = Text;
                 var clickInfo = e.GetCurrentPoint(this);
                 if (text != null && !(clickInfo.Pointer?.Captured is Border))

src/Avalonia.Controls/TextBoxTextInputMethodClient.cs

@@ -13,6 +13,7 @@ namespace Avalonia.Controls
         private TextPresenter? _presenter;
         private bool _selectionChanged;
         private bool _isInChange;
+        private ITextInputMethodImpl? _im;
 
         public override Visual TextViewVisual => _presenter!;
 
@@ -24,7 +25,7 @@ namespace Avalonia.Controls
                 {
                     return "";
                 }
-                
+
                 if (_parent.CaretIndex != _presenter.CaretIndex)
                 {
                     _presenter.SetCurrentValue(TextPresenter.CaretIndexProperty, _parent.CaretIndex);
@@ -34,7 +35,7 @@ namespace Avalonia.Controls
                 {
                     _presenter.SetCurrentValue(TextPresenter.TextProperty, _parent.Text);
                 }
-                
+
                 var lineIndex = _presenter.TextLayout.GetLineIndexFromCharacterIndex(_presenter.CaretIndex, false);
 
                 var textLine = _presenter.TextLayout.TextLines[lineIndex];
@@ -125,6 +126,11 @@ namespace Avalonia.Controls
             if (_parent != null)
             {
                 _parent.PropertyChanged += OnParentPropertyChanged;
+                _im = (_parent.VisualRoot as ITextInputMethodRoot)?.InputMethod;
+            }
+            else
+            {
+                _im = null;
             }
 
             var oldPresenter = _presenter;
@@ -133,7 +139,7 @@ namespace Avalonia.Controls
             {
                 oldPresenter.ClearValue(TextPresenter.PreeditTextProperty);
 
-                oldPresenter.CaretBoundsChanged -= (s,e) => RaiseCursorRectangleChanged();
+                oldPresenter.CaretBoundsChanged -= (s, e) => RaiseCursorRectangleChanged();
             }
 
             _presenter = presenter;
@@ -161,6 +167,17 @@ namespace Avalonia.Controls
             _presenter.SetCurrentValue(TextPresenter.PreeditTextCursorPositionProperty, cursorPos);
         }
 
+        public override void ShowInputPanel()
+        {
+            base.ShowInputPanel();
+
+            if (_parent is { } && _im is { })
+            {
+                _im.SetOptions(TextInputOptions.FromStyledElement(_parent));
+                _im.SetClient(this);
+            }
+        }
+
         private static string GetTextLineText(TextLine textLine)
         {
             var builder = StringBuilderCache.Acquire(textLine.Length);