buildTextSpan method Null safety

TextSpan buildTextSpan()

Builds TextSpan from current editing value.

By default makes text in composing range appear as underlined. Descendants can override this method to customize appearance of text.

Implementation

TextSpan buildTextSpan() {
  if (widget.obscureText) {
    String text = _value.text;
    text = widget.obscuringCharacter * text.length;
    // Reveal the latest character in an obscured field only on mobile.
    const Set<TargetPlatform> mobilePlatforms = <TargetPlatform> {
      TargetPlatform.android, TargetPlatform.iOS, TargetPlatform.fuchsia,
    };
    final bool breiflyShowPassword = WidgetsBinding.instance.platformDispatcher.brieflyShowPassword
                                  && mobilePlatforms.contains(defaultTargetPlatform);
    if (breiflyShowPassword) {
      final int? o = _obscureShowCharTicksPending > 0 ? _obscureLatestCharIndex : null;
      if (o != null && o >= 0 && o < text.length)
        text = text.replaceRange(o, o + 1, _value.text.substring(o, o + 1));
    }
    return TextSpan(style: widget.style, text: text);
  }
  if (_placeholderLocation >= 0 && _placeholderLocation <= _value.text.length) {
    final List<_ScribblePlaceholder> placeholders = <_ScribblePlaceholder>[];
    final int placeholderLocation = _value.text.length - _placeholderLocation;
    if (_isMultiline) {
      // The zero size placeholder here allows the line to break and keep the caret on the first line.
      placeholders.add(const _ScribblePlaceholder(child: SizedBox(), size: Size.zero));
      placeholders.add(_ScribblePlaceholder(child: const SizedBox(), size: Size(renderEditable.size.width, 0.0)));
    } else {
      placeholders.add(const _ScribblePlaceholder(child: SizedBox(), size: Size(100.0, 0.0)));
    }
    return TextSpan(style: widget.style, children: <InlineSpan>[
        TextSpan(text: _value.text.substring(0, placeholderLocation)),
        ...placeholders,
        TextSpan(text: _value.text.substring(placeholderLocation)),
      ],
    );
  }

  // Read only mode should not paint text composing.
  return widget.controller.buildTextSpan(
    context: context,
    style: widget.style,
    withComposing: !widget.readOnly && _hasFocus,
  );
}