attributed_text_styles.dart

import 'package:attributed_text/attributed_text.dart';
import 'package:flutter/painting.dart';
import 'package:super_editor/src/infrastructure/_logging.dart';

/// Creates the desired [TextStyle] given the [attributions] associated
/// with a span of text.
///
/// The [attributions] set may be empty.
typedef AttributionStyleBuilder = TextStyle Function(Set<Attribution> attributions);

extension ToSpanRange on TextRange {
  SpanRange toSpanRange() => SpanRange(start: start, end: end);
}

extension ComputerTextSpan on AttributedText {
  /// Returns a Flutter [TextSpan] that is styled based on the
  /// attributions within this [AttributedText].
  ///
  /// The given [styleBuilder] interprets the meaning of every
  /// attribution and constructs [TextStyle]s accordingly.
  // TODO: remove this method and use [visitAttributions()] to compute TextSpan
  TextSpan computeTextSpan(AttributionStyleBuilder styleBuilder) {
    attributionsLog.fine('text length: ${text.length}');
    attributionsLog.fine('attributions used to compute spans:');
    attributionsLog.fine(spans.toString());

    if (text.isEmpty) {
      // There is no text and therefore no attributions.
      attributionsLog.fine('text is empty. Returning empty TextSpan.');
      return TextSpan(text: '', style: styleBuilder({}));
    }

    final collapsedSpans = spans.collapseSpans(contentLength: text.length);
    final textSpans = collapsedSpans
        .map((attributedSpan) => TextSpan(
              text: text.substring(attributedSpan.start, attributedSpan.end + 1),
              style: styleBuilder(attributedSpan.attributions),
            ))
        .toList();

    return textSpans.length == 1
        ? textSpans.first
        : TextSpan(
            children: textSpans,
            style: styleBuilder({}),
          );
  }
}