touchLine method

Implementation

void touchLine(int x, int y, int width) {
  if (y < 0 || y >= lines.length) return;
  if (width <= 0) return;

  if (y >= touched.length) {
    touched = [
      ...touched,
      ...List<LineData?>.filled(y - touched.length + 1, null),
    ];
  }
  if (y >= dirtyRows.length) {
    dirtyRows = [
      ...dirtyRows,
      ...List<bool>.filled(y - dirtyRows.length + 1, false),
    ];
  }
  if (y >= dirtyBits.length) {
    final width = this.width();
    dirtyBits = [
      ...dirtyBits,
      ...List<Uint32List>.generate(
        y - dirtyBits.length + 1,
        (_) => Uint32List(_dirtyWordCount(width)),
      ),
    ];
  }

  final ch = touched[y];
  final first = x;
  final last = x + width;
  dirtyRows[y] = true;
  _markDirtyBits(y, first, last);
  if (ch == null) {
    touched[y] = LineData(
      firstCell: first,
      lastCell: last,
      spans: <DirtySpan>[DirtySpan(start: first, end: last)],
    );
  } else {
    final prevFirst = ch.firstCell == -1 ? first : ch.firstCell;
    final prevLast = ch.lastCell == -1 ? last : ch.lastCell;
    if (ch.overflowed) {
      final mergedFirst = first < prevFirst ? first : prevFirst;
      final mergedLast = last > prevLast ? last : prevLast;
      touched[y] = LineData(
        firstCell: mergedFirst,
        lastCell: mergedLast,
        spans: <DirtySpan>[DirtySpan(start: mergedFirst, end: mergedLast)],
        overflowed: true,
      );
      return;
    }
    if (ch.spans.isNotEmpty) {
      final lastSpan = ch.spans.last;
      if (first <= lastSpan.end && first >= lastSpan.start) {
        final mergedSpans = List<DirtySpan>.from(ch.spans, growable: false);
        mergedSpans[mergedSpans.length - 1] = DirtySpan(
          start: lastSpan.start,
          end: last > lastSpan.end ? last : lastSpan.end,
        );
        touched[y] = LineData(
          firstCell: first < prevFirst ? first : prevFirst,
          lastCell: last > prevLast ? last : prevLast,
          spans: mergedSpans,
          overflowed: false,
        );
        return;
      }
    }
    final spans = _mergeDirtySpans(
      ch.spans,
      DirtySpan(start: first, end: last),
    );
    touched[y] = LineData(
      firstCell: first < prevFirst ? first : prevFirst,
      lastCell: last > prevLast ? last : prevLast,
      spans: spans.spans,
      overflowed: spans.overflowed || ch.overflowed,
    );
  }
}