Flutter:创建新行后文本字段光标不会下降

Question

我正在使用文本字段小部件进行文本编辑:

          new TextField(
            controller: _controller,
            maxLines: null,
          ),

问题:当我开始一个新行时，光标直到我开始输入文本才会下降。

截图如下:

我的问题:如何让光标在创建后立即下移到新行？

Answer 1

根据:Github

/lib/src/rendering/editable.dart 中的 _paintCaret 方法必须修改，textField 中的 maxLines 参数必须为 null。它对我有用，希望成为临时解决方法。

/// MODIFIED:
void _paintCaret(Canvas canvas, Offset effectiveOffset) {
  assert(_textLayoutLastWidth == constraints.maxWidth);
  final Offset caretOffset = _textPainter.getOffsetForCaret(_selection.extent, 
    _caretPrototype);
  final Paint paint = new Paint()..color = _cursorColor;
  //final Rect caretRect = _caretPrototype.shift(caretOffset + effectiveOffset);

  var textLength = 0;
  var inputString = '';
  if (text.children != null) {
    for (var ts in text.children) {
      textLength += ts.text.length;
      inputString += ts.text;
    }
  } else if (text.text != null) {
    textLength += text.text.length;
    inputString += text.text;
  }
  final Rect tmpRect = _caretPrototype.shift(caretOffset + effectiveOffset);
  Rect caretRect = new Rect.fromLTRB(tmpRect.left, _viewportExtent - 2.0 - 
    tmpRect.height, tmpRect.right, _viewportExtent - 2.0);
  if ((tmpRect.top.abs() - caretRect.top.abs()).abs() > 10) {
    caretRect = new Rect.fromLTWH(0.0, caretRect.top, caretRect.width, 
      caretRect.height);
  }
  if (_selection.extentOffset != textLength){
    caretRect = tmpRect;
  }
  if (caretRect.left != 0 && inputString[_selection.extentOffset - 1] == '\n') {
    _selection = new TextSelection.fromPosition(new TextPosition(offset: 
     _selection.extentOffset));
    caretRect = _caretPrototype.shift(caretOffset + effectiveOffset);
  }

  canvas.drawRect(caretRect, paint);
  if (caretRect != _lastCaretRect) {
    _lastCaretRect = caretRect;
    if (onCaretChanged != null)
      onCaretChanged(caretRect);
  }
}