widgetsWithScreenPositions method

List<ChildInfo> widgetsWithScreenPositions({ bool forceRebuild = false, })

Currently rendered widgets with their position info

Implementation

List<ChildInfo> widgetsWithScreenPositions({bool forceRebuild = false}) {
  if (!_init) return [];

  if (_focusChildOnBuild != null) {
    // if this is the first build, focus on the child if set
    focusOnChild(_focusChildOnBuild!, animate: false);
    _focusChildOnBuild = null;
  }

  // _renderCacheDirty depends on _markDirty + other stuff
  if (!_renderCacheDirty && !forceRebuild) {
    // if the render cache is not dirty, we can use the cached result
    return _lastRenderedWidgets;
  }

  _lastProcessedOffset = _gsTopLeftOffset;
  _lastProcessedScale = _scale;
  _markDirty = false;

  final idsToBuild = _childrenWithinBuildArea(_gsCenter, buildExtent);

  // do the needed callbacks
  if (onWidgetEnteredRender != null || onWidgetExitedRender != null) {
    final newRenderedWidgets = idsToBuild.toSet();
    final exitedWidgets = _renderedWidgets.difference(newRenderedWidgets);
    final enteredWidgets = newRenderedWidgets.difference(_renderedWidgets);

    Future.microtask(() {
      // so that the build is not blocked
      for (final id in exitedWidgets) {
        onWidgetExitedRender?.call(id);
      }
      for (final id in enteredWidgets) {
        onWidgetEnteredRender?.call(id);
      }
    });
  }
  _renderedWidgets = idsToBuild.toSet();

  return _lastRenderedWidgets = idsToBuild.map((id) {
    final item = _children[id]!;
    final ssPosition = gsToSs(item.gsPosition, _gsTopLeftOffset, _scale);
    var child = item.widget;
    if (debug) {
      child = _Debug(
        key: ValueKey<String>(id),
        id: id,
        gs: item.gsPosition,
        ss: ssPosition,
        child: child,
      );
    }
    return ChildInfo(
      id: id,
      gsPosition: item.gsPosition,
      ssPosition: ssPosition,
      child: child,
    );
  }).toList();
}