Add keyboard cursor moving: left, right.

Author: ilopX

patterns/state/manipulator_state/states/selections/text/text_cursor.dart

@@ -7,11 +7,10 @@ class TextCursor {
 
   double get xCoordinate => _xPosition;
 
-  void changePosition(double x, double y) {
+  void changePosition(double x) {
     x = x - _shape.x;
-    y = y - _shape.y;
 
-    final pos = _shape.paragraph.getPositionForOffset(Offset(x, y));
+    final pos = _shape.paragraph.getPositionForOffset(Offset(x, _shape.y));
     _charIndex = pos.offset;
 
     final range = _shape.paragraph.getBoxesForRange(
@@ -26,41 +25,59 @@ class TextCursor {
     }
   }
 
-  String inputText(String char) {
-    final start = _shape.text.substring(0, _charIndex);
-    final end = _shape.text.substring(_charIndex);
-    _shape.text = '$start$char$end';
-    final range = _shape.paragraph.getBoxesForRange(_charIndex, ++_charIndex);
-    _xPosition = _shape.x;
+  void inputText(String char) {
+    _changeText(char: char);
+    moveRight();
+  }
 
-    if (range.isNotEmpty) {
-      _xPosition += range.first.right;
+  void backspace() {
+    if (_charIndex <= 0) {
+      return;
     }
 
-    return '$start$char$end';
+    _changeText(removeChars: -1);
+    moveLeft();
   }
 
-  void backspace() {
+  void moveLeft() {
+    _charIndex--;
+    _xPosition = _shape.x;
+
     if (_charIndex <= 0) {
+      _charIndex = 0;
       return;
     }
 
-    final start = _shape.text.substring(0, _charIndex - 1);
-    final end = _shape.text.length > start.length
-        ? _shape.text.substring(_charIndex)
-        : '';
+    final range = _shape.paragraph.getBoxesForRange(_charIndex - 1, _charIndex);
+
+    if (range.isNotEmpty) {
+      _xPosition += range.first.right;
+    }
+  }
 
-    _shape.text = '$start$end';
+  void moveRight() {
+    _charIndex++;
+    _xPosition = _shape.x;
+
+    if (_charIndex >= _shape.text.length) {
+      _charIndex = _shape.text.length;
+      _xPosition += _shape.width;
+      return;
+    }
 
     final range = _shape.paragraph.getBoxesForRange(_charIndex - 1, _charIndex);
-    _xPosition = _shape.x;
 
     if (range.isNotEmpty) {
-      _xPosition += range.first.left;
-    } else {
-      _xPosition += _shape.width;
+      _xPosition += range.first.right;
     }
-    _charIndex--;
+  }
+
+  void _changeText({String char = '', int removeChars = 0}) {
+    final start = _shape.text.substring(0, _charIndex + removeChars);
+    final end = _shape.text.length > start.length
+        ? _shape.text.substring(_charIndex)
+        : '';
+    _shape.text = '$start$char$end';
   }
 
   final TextShape _shape;

patterns/state/manipulator_state/states/selections/text_change_state.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
@@ -14,19 +16,27 @@ class TextChangeState extends SelectionState<TextShape> {
 
   @override
   void init() {
-    _textCursor.changePosition(_startPointer.dx, _startPointer.dy);
+    _textCursor.changePosition(_startPointer.dx);
     context.cursor = SystemMouseCursors.text;
+
+    _cursorAnimateTimer = Timer.periodic(Duration(milliseconds: 500), (_) {
+      _isShowCursor = !_isShowCursor;
+      context.update();
+    });
+
     context.update();
   }
 
   @override
   void mouseDown(double x, double y) {
     if (selectedShape.rect.contains(Offset(x, y))) {
-      _textCursor.changePosition(x, y);
+      _textCursor.changePosition(x);
+      _isShowCursor = true;
       context.update();
       return;
     }
 
+    _cursorAnimateTimer.cancel();
     super.mouseDown(x, y);
   }
 
@@ -35,19 +45,27 @@ class TextChangeState extends SelectionState<TextShape> {
     if (keyEvent is KeyDownEvent || keyEvent is KeyRepeatEvent) {
       if (keyEvent.physicalKey == PhysicalKeyboardKey.backspace) {
         _textCursor.backspace();
-        context.update();
+      } else if (keyEvent.physicalKey == PhysicalKeyboardKey.arrowLeft) {
+        _textCursor.moveLeft();
+      } else if (keyEvent.physicalKey == PhysicalKeyboardKey.arrowRight) {
+        _textCursor.moveRight();
       } else if (keyEvent.character != null) {
         _textCursor.inputText(keyEvent.character!);
-        context.update();
       }
+
+      _isShowCursor = true;
+      context.update();
     }
   }
 
   @override
   void paint(Canvas canvas) {
     context.paintStyle.paintSelectedText(selectedShape, canvas);
     super.paint(canvas);
-    context.paintStyle.paintTextCursor(_textCursor, selectedShape, canvas);
+
+    if (_isShowCursor) {
+      context.paintStyle.paintTextCursor(_textCursor, selectedShape, canvas);
+    }
   }
 
   @override
@@ -62,12 +80,13 @@ class TextChangeState extends SelectionState<TextShape> {
     context.cursor = SystemMouseCursors.basic;
   }
 
-
   @override
   String toString() {
     return '${super.toString()} + Text Change State';
   }
 
   final Offset _startPointer;
   final TextCursor _textCursor;
+  bool _isShowCursor = true;
+  late Timer _cursorAnimateTimer;
 }