layoutChildren method

void layoutChildren(BoxConstraints constraints, { List<int>? hideWidgets, TextPainter? textPainter, bool dry = false, })

Implementation

void layoutChildren(
  BoxConstraints constraints, {
  List<int>? hideWidgets,
  TextPainter? textPainter,
  bool dry = false,
}) {
  if (childCount == 0) {
    return;
  }
  RenderBox? child = firstChild;
  _placeholderDimensions = List<PlaceholderDimensions>.filled(
      textChildCount, PlaceholderDimensions.empty,
      growable: false);
  // Only constrain the width to the maximum width of the paragraph.
  // Leave height unconstrained, which will overflow if expanded past.
  BoxConstraints boxConstraints =
      BoxConstraints(maxWidth: constraints.maxWidth);
  // The content will be enlarged by textScaleFactor during painting phase.
  // We reduce constraints by textScaleFactor, so that the content will fit
  // into the box once it is enlarged.
  boxConstraints = boxConstraints / textScaleFactor;
  int childIndex = 0;
  while (child != null && childIndex < textChildCount) {
    double? baselineOffset;
    final Size childSize;

    if (!dry) {
      // Only constrain the width to the maximum width of the paragraph.
      // Leave height unconstrained, which will overflow if expanded past.
      child.layout(
        hideWidgets != null && hideWidgets.contains(childIndex)
            ? const BoxConstraints(maxWidth: 0)
            : boxConstraints,
        parentUsesSize: true,
      );
      childSize = child.size;
      switch (_placeholderSpans[childIndex].alignment) {
        case ui.PlaceholderAlignment.baseline:
          baselineOffset = child.getDistanceToBaseline(
            _placeholderSpans[childIndex].baseline!,
          );
          break;
        case ui.PlaceholderAlignment.aboveBaseline:
        case ui.PlaceholderAlignment.belowBaseline:
        case ui.PlaceholderAlignment.bottom:
        case ui.PlaceholderAlignment.middle:
        case ui.PlaceholderAlignment.top:
          baselineOffset = null;
          break;
      }
    } else {
      assert(_placeholderSpans[childIndex].alignment !=
          ui.PlaceholderAlignment.baseline);
      childSize = child.getDryLayout(boxConstraints);
    }

    _placeholderDimensions![childIndex] = PlaceholderDimensions(
      size: childSize,
      alignment: _placeholderSpans[childIndex].alignment,
      baseline: _placeholderSpans[childIndex].baseline,
      baselineOffset: baselineOffset,
    );
    child = childAfter(child);
    childIndex += 1;
  }
  (textPainter ?? this.textPainter)
      .setPlaceholderDimensions(_placeholderDimensions);
}