SliverCrossAxisGroup class

A sliver that places multiple sliver children in a linear array along the cross axis.

Layout algorithm

This section describes how the framework causes RenderSliverCrossAxisGroup to position its children.

Layout for a RenderSliverCrossAxisGroup has four steps:

1. Layout each child with a null or zero flex factor with cross axis constraint being whatever cross axis space is remaining after laying out any previous sliver. Slivers with null or zero flex factor should determine their own SliverGeometry.crossAxisExtent. For example, the SliverConstrainedCrossAxis widget uses either SliverConstrainedCrossAxis.maxExtent or SliverConstraints.crossAxisExtent, deciding between whichever is smaller.
2. Divide up the remaining cross axis space among the children with non-zero flex factors according to their flex factor. For example, a child with a flex factor of 2.0 will receive twice the amount of cross axis space as a child with a flex factor 1.0.
3. Layout each of the remaining children with the cross axis constraint allocated in the previous step.
4. Set the geometry to that of whichever child has the longest SliverGeometry.scrollExtent with the SliverGeometry.crossAxisExtent adjusted to SliverConstraints.crossAxisExtent.

See also:

• SliverCrossAxisExpanded, which is the ParentDataWidget for setting a flex value to a widget.
• SliverConstrainedCrossAxis, which is a RenderObjectWidget for setting an extent to constrain the widget to.
• SliverMainAxisGroup, which is the RenderObjectWidget for laying out multiple slivers along the main axis.