more keyboard edit function

Assets/UIWidgets/painting/text_painter.cs

 
             return null;
         }
-
+        
         public List<TextBox> getBoxesForSelection(TextSelection selection)
         {
             D.assert(!_needsLayout);
             D.assert(!_needsLayout);
             var range = _paragraph.getWordBoundary(position.offset);
             return new TextRange(range.start, range.end);
+        }
+        
+        public TextPosition getPositionVerticalMove(TextPosition position, int move)
+        {
+            D.assert(!_needsLayout);
+            var offset = getOffsetForCaret(position, Rect.zero);
+            var line = _paragraph.getLine(position);
+            var targetLineStart = _paragraph.getLineStart(line + move);
+            var newLineOffset = getOffsetForCaret(targetLineStart, Rect.zero);
+            return getPositionForOffset(new Offset(offset.dx, newLineOffset.dy));
+        }
+
+        public int getLineIndex(TextPosition position)
+        {
+            D.assert(!_needsLayout);
+            return _paragraph.getLine(position);
+        public TextPosition getLineStartPosition(int line)
+        {
+            D.assert(!_needsLayout);
+            return _paragraph.getLineStart(line);
+        }
+        
+        public TextPosition getLineEndPosition(int line)
+        {
+            D.assert(!_needsLayout);
+            return _paragraph.getLineEnd(line);
+        }
+
+        public TextPosition getWordRight(TextPosition position)
+        {
+            D.assert(!_needsLayout);
+            var offset = position.offset;
+            while(true)
+            {
+                var range = _paragraph.getWordBoundary(offset);
+                if (range.end == range.start)
+                {
+                    break;
+                }
+                if (!char.IsWhiteSpace((char)(text.codeUnitAt(range.start)??0)))
+                {
+                    return new TextPosition(range.end);
+                }
+                offset = range.end;
+            }
+            
+            return new TextPosition(offset);
+        }
+        
+        public TextPosition getWordLeft(TextPosition position)
+        {
+            D.assert(!_needsLayout);
+            var offset = Math.Max(position.offset - 1, 0);
+            while(true)
+            {
+                var range = _paragraph.getWordBoundary(offset);
+                if (!char.IsWhiteSpace((char)(text.codeUnitAt(range.start)??0)))
+                {
+                    return new TextPosition(range.start);
+                }
+                offset = Math.Max(range.start - 1, 0);
+                if (offset == 0)
+                {
+                    break;
+                }
+            }
+            
+            return new TextPosition(offset);
+        }
+        
         private ParagraphStyle _createParagraphStyle(TextDirection defaultTextDirection = TextDirection.ltr)
         {
             if (_text.style == null)

Assets/UIWidgets/rendering/editable.cs

             var caretOffset = _textPainter.getOffsetForCaret(caretPosition, _caretPrototype);
             return Rect.fromLTWH(0.0, 0.0, _kCaretWidth, preferredLineHeight).shift(caretOffset + _paintOffset);
         }
+
+        public TextPosition getPositionDown(TextPosition position)
+        {
+            return _textPainter.getPositionVerticalMove(position, 1);
+        }
+        public TextPosition getPositionUp(TextPosition position)
+        {
+            return _textPainter.getPositionVerticalMove(position, -1);
+        }
+        
+        public TextPosition getLineStartPosition(TextPosition position)
+        {
+            return _textPainter.getLineStartPosition(_textPainter.getLineIndex(position));
+        }
+        
+        public TextPosition getLineEndPosition(TextPosition position)
+        {
+            return _textPainter.getLineEndPosition(_textPainter.getLineIndex(position));
+        }
+        
+        public TextPosition getWordRight(TextPosition position)
+        {
+            return _textPainter.getWordRight(position);
+        } 
+        
+        public TextPosition getWordLeft(TextPosition position)
+        {
+            return _textPainter.getWordLeft(position);
+        } 
+
         protected override double computeMinIntrinsicWidth(double height) {
             _layoutText(double.PositiveInfinity);
             return _textPainter.minIntrinsicWidth;

Assets/UIWidgets/service/text_input.cs

             );
         }
 
-        public TextEditingValue deleteSelection()
+        public TextEditingValue deleteSelection(bool backDelete = true)
-                if (selection.start == 0)
+                if (backDelete)
+                {
+                    if (selection.start == 0)
+                    {
+                        return this;
+                    }
+                    return this.copyWith(text: text.Substring(0, selection.start - 1) + selection.textAfter(this.text), 
+                        selection: TextSelection.collapsed(selection.start - 1));
+                }
+
+                if (selection.start >= text.Length)
-                return this.copyWith(text: text.Substring(0, selection.start - 1) + selection.textAfter(this.text), 
-                    selection: TextSelection.collapsed(selection.start - 1));
+                return this.copyWith(text: text.Substring(0, selection.start) + text.Substring(selection.start + 1));
             }
             else
             {
     public interface TextInputClient
     {
         void updateEditingValue(TextEditingValue value);
+
+        TextEditingValue getValueForOperation(TextEditOp operation);
         // void performAction(TextInputAction action);
     }
    
             if (s_Keyactions.ContainsKey(e))
             {
                 TextEditOp op = s_Keyactions[e];
-                var newValue = performOperation(op);
+                var newValue =_currentConnection._client.getValueForOperation(op);
                 if (_value != newValue)
                 {
                     _value = newValue;
         }
     }
     
-    internal enum TextEditOp
+    public enum TextEditOp
     {
         MoveLeft,
         MoveRight,

Assets/UIWidgets/ui/txt/paragraph.cs

 using System;
 using System.Collections.Generic;
+using UIWidgets.foundation;
 using UIWidgets.ui.txt;
 using UnityEngine;
 
                             _characterPositions, line.start, line.endExcludingWhitespace);
                     }
                 }
-                
             }
             
             computeWidthMetrics(maxWordWidth);
                 double top = baseLine - run.fontMetrics.ascent;
                 double bottom = baseLine + run.fontMetrics.descent;
 
-                // double left, right;
                 var from = Math.Max(start, run.codeUnits.start);
                 var to = Math.Min(end, run.codeUnits.end);
                 if (from < to)
                 return new PositionWithAffinity(index, TextAffinity.downstream);
             } else
             {
-                return new PositionWithAffinity(index, TextAffinity.upstream);
+                return new PositionWithAffinity(index + 1, TextAffinity.upstream);
+            }
+        }
+
+        public int getLine(TextPosition position)
+        {
+            D.assert(!_needsLayout);
+            if (position.offset < 0)
+            {
+                return 0;
+            }
+
+            var offset = position.offset;
+            if (position.affinity == TextAffinity.upstream && offset > 0)
+            {
+                offset = _isUtf16Surrogate(_text[offset - 1]) ? offset - 2 : offset - 1;
+            }
+            
+            var lineCount = getLineCount();
+            for (int lineIndex = 0; lineIndex < getLineCount(); ++lineIndex)
+            {
+                var line = _lineRanges[lineIndex];
+                if (offset >= line.start && offset <= line.end)
+                {
+                    return lineIndex;
+                }
+
+            return Math.Max(lineCount - 1, 0);
+        public TextPosition getLineStart(int lineIndex)
+        {
+            lineIndex = Math.Min(getLineCount() - 1, Math.Max(lineIndex, 0));
+            return new TextPosition(_lineRanges[lineIndex].start);
+        }
+        
+        public TextPosition getLineEnd(int lineIndex)
+        {
+            lineIndex = Math.Min(getLineCount() - 1, Math.Max(lineIndex, 0));
+            return new TextPosition(_lineRanges[lineIndex].end);
+        }
+        
         public IndexRange getWordBoundary(int offset)
         {
             WordSeparate s = new WordSeparate(_text);
                 }
             }
         }
-        
+
+        public int getLineCount()
+        {
+            return _lineHeights.Count;
+        }
 
         private void computeWidthMetrics(double maxWordWidth)
         {
                     yOffset = yOffsetOriginal;
                 }
             }
+        }
+        
+        private static bool _isUtf16Surrogate(int value)
+        {
+            return (value & 0xF800) == 0xD800;
         }
         
     }

Assets/UIWidgets/ui/txt/word_separate.cs

         
         public IndexRange findWordRange(int index)
         {
+            if (index >= _text.Length)
+            {
+                return new IndexRange(0, 0);
+            }
             var t = classifyChar(index);
             int start = index;
             for (int i = index; i >= 0; --i)

Assets/UIWidgets/widgets/editable_text.cs

             _formatAndSetValue(value);
         }
 
+        public TextEditingValue getValueForOperation(TextEditOp operation)
+        {
+            TextPosition newPosition = null;
+            switch (operation)
+            {
+                    case TextEditOp.MoveLeft:
+                    return _value.moveLeft();
+                case TextEditOp.MoveRight:
+                    return _value.moveRight();
+                case TextEditOp.MoveUp:             
+                    newPosition = this.renderEditable.getPositionUp(new TextPosition(_value.selection.start, _value.selection.affinity));
+                    return _value.copyWith(selection: TextSelection.fromPosition(newPosition));
+               case TextEditOp.MoveDown:
+                   newPosition = this.renderEditable.getPositionDown(new TextPosition(_value.selection.start, _value.selection.affinity));
+                   return _value.copyWith(selection: TextSelection.fromPosition(newPosition));
+                case TextEditOp.MoveLineStart:      
+                    newPosition = this.renderEditable.getLineStartPosition(new TextPosition(_value.selection.start, _value.selection.affinity));
+                    return _value.copyWith(selection: TextSelection.fromPosition(newPosition));
+                case TextEditOp.MoveLineEnd:      
+                    newPosition = this.renderEditable.getLineEndPosition(new TextPosition(_value.selection.start, _value.selection.affinity));
+                    return _value.copyWith(selection: TextSelection.fromPosition(newPosition));
+               case TextEditOp.MoveWordRight:      
+                   newPosition = this.renderEditable.getWordRight(new TextPosition(_value.selection.start));
+                   return _value.copyWith(selection: TextSelection.fromPosition(newPosition));
+                case TextEditOp.MoveWordLeft:      
+                    newPosition = this.renderEditable.getWordLeft(new TextPosition(_value.selection.start));
+                    return _value.copyWith(selection: TextSelection.fromPosition(newPosition));
+//                case TextEditOp.MoveToStartOfNextWord:      MoveToStartOfNextWord(); break;
+//                case TextEditOp.MoveToEndOfPreviousWord:        MoveToEndOfPreviousWord(); break;
+
+                case TextEditOp.MoveTextStart:
+                    return _value.copyWith(selection: TextSelection.collapsed(0));
+                case TextEditOp.MoveTextEnd:        
+                    return _value.copyWith(selection: TextSelection.collapsed(_value.text.Length));
+//                case TextEditOp.MoveParagraphForward:   MoveParagraphForward(); break;
+//                case TextEditOp.MoveParagraphBackward:  MoveParagraphBackward(); break;
+//                case TextEditOp.MoveGraphicalLineStart: MoveGraphicalLineStart(); break;
+//                case TextEditOp.MoveGraphicalLineEnd: MoveGraphicalLineEnd(); break;
+                  case TextEditOp.SelectLeft:
+                      return _value.extendLeft();
+                  case TextEditOp.SelectRight:
+                      return _value.extendRight();
+                  case TextEditOp.SelectUp:           
+                      newPosition = this.renderEditable.getPositionUp(_value.selection.extendPos);
+                      return _value.copyWith(selection: _value.selection.copyWith(extentOffset: newPosition.offset));
+                  case TextEditOp.SelectDown:        
+                      newPosition = this.renderEditable.getPositionDown(_value.selection.extendPos);
+                      return _value.copyWith(selection: _value.selection.copyWith(extentOffset: newPosition.offset));
+                  case TextEditOp.SelectWordRight:        
+                      newPosition = this.renderEditable.getWordRight(_value.selection.extendPos);
+                      return _value.copyWith(selection: _value.selection.copyWith(extentOffset: newPosition.offset));
+                  case TextEditOp.SelectWordLeft:     
+                      newPosition = this.renderEditable.getWordLeft(_value.selection.extendPos);
+                      return _value.copyWith(selection: _value.selection.copyWith(extentOffset: newPosition.offset));
+//                case TextEditOp.SelectToEndOfPreviousWord:  SelectToEndOfPreviousWord(); break;
+//                case TextEditOp.SelectToStartOfNextWord:    SelectToStartOfNextWord(); break;
+//
+                 case TextEditOp.SelectTextStart:        
+                     return _value.copyWith(selection: _value.selection.copyWith(extentOffset: 0));
+               case TextEditOp.SelectTextEnd:      
+                   return _value.copyWith(selection: _value.selection.copyWith(extentOffset: _value.text.Length));
+//                case TextEditOp.ExpandSelectGraphicalLineStart: ExpandSelectGraphicalLineStart(); break;
+//                case TextEditOp.ExpandSelectGraphicalLineEnd: ExpandSelectGraphicalLineEnd(); break;
+//                case TextEditOp.SelectParagraphForward:     SelectParagraphForward(); break;
+//                case TextEditOp.SelectParagraphBackward:    SelectParagraphBackward(); break;
+//                case TextEditOp.SelectGraphicalLineStart: SelectGraphicalLineStart(); break;
+//                case TextEditOp.SelectGraphicalLineEnd: SelectGraphicalLineEnd(); break;
+                 case TextEditOp.Delete: return _value.deleteSelection(false);
+                case TextEditOp.Backspace:
+                    return _value.deleteSelection();
+            }
+
+            return _value;
+        }
+
         void _updateRemoteEditingValueIfNeeded()
         {
             if (!_hasInputConnection)