getChildLayoutConstraints method

BoxConstraints getChildLayoutConstraints(BoxConstraints constraints, RenderBox child, ViewableMixin model)

Implementation

BoxConstraints getChildLayoutConstraints(
    BoxConstraints constraints, RenderBox child, ViewableMixin model) {
  // get the child's width from the model
  // and tighten the child's width constraint
  var parentWidth = widthOf(child.parent);
  var childWidth = model.getWidth(widthParent: parentWidth);
  if (childWidth != null) {
    constraints = constraints.tighten(width: childWidth);
  }

  // get the child's height from the model
  // and tighten the child's height constraint
  var parentHeight = heightOf(child.parent);
  var childHeight = model.getHeight(heightParent: parentHeight);
  if (childHeight != null) {
    constraints = constraints.tighten(height: childHeight);
  }

  // set child min/max widths as defined in the model
  if (!constraints.hasTightWidth) {
    var childMinWidth = model.getMinWidth(widthParent: parentHeight);
    if (childMinWidth != null && childMinWidth > constraints.minWidth) {
      constraints = BoxConstraints(
          minWidth: childMinWidth,
          maxWidth: constraints.maxWidth,
          minHeight: constraints.minHeight,
          maxHeight: constraints.maxHeight);
    }
    var childMaxWidth = model.getMaxWidth(widthParent: parentHeight);
    if (childMaxWidth != null && childMaxWidth < constraints.maxWidth) {
      constraints = BoxConstraints(
          minWidth: constraints.minWidth,
          maxWidth: childMaxWidth,
          minHeight: constraints.minHeight,
          maxHeight: constraints.maxHeight);
    }
  }

  // set child min/max heights as defined in the model
  if (!constraints.hasTightHeight) {
    var childMinHeight = model.getMinHeight(heightParent: parentHeight);
    if (childMinHeight != null && childMinHeight > constraints.minHeight) {
      constraints = BoxConstraints(
          minWidth: constraints.minWidth,
          maxWidth: constraints.maxWidth,
          minHeight: childMinHeight,
          maxHeight: constraints.maxHeight);
    }
    var childMaxHeight = model.getMaxHeight(heightParent: parentHeight);
    if (childMaxHeight != null && childMaxHeight < constraints.maxHeight) {
      constraints = BoxConstraints(
          minWidth: constraints.minWidth,
          maxWidth: constraints.maxWidth,
          minHeight: constraints.minHeight,
          maxHeight: childMaxHeight);
    }
  }

  // If both of us are unconstrained in the horizontal axis,
  // tighten the child's width constraint prior to layout
  if (!constraints.hasBoundedWidth && model.canExpandInfinitelyWide) {
    constraints = BoxConstraints(
        minWidth: constraints.minWidth,
        maxWidth: parentWidth,
        minHeight: constraints.minHeight,
        maxHeight: constraints.maxHeight);
  }

  // If both of us are unconstrained in the vertical axis,
  // tighten the child's height constraint prior to layout
  if (!constraints.hasBoundedHeight && model.canExpandInfinitelyHigh) {
    constraints = BoxConstraints(
        minWidth: constraints.minWidth,
        maxWidth: constraints.maxWidth,
        minHeight: constraints.minHeight,
        maxHeight: parentHeight);
  }

  // if the model wants to expand in the horizontal and has an unbounded
  // width, then set the min width to the parent width. This happens for
  // instance when a <box expand="true"/> is inside a <scroller/>. Normally the
  // expand would be set to false in the view. This ensures the widget is at least as
  // wide as the first parent with a constrained width.
  // if (model.expandHorizontally && !constraints.hasBoundedWidth)
  // {
  //   constraints = BoxConstraints(minWidth: parentWidth, maxWidth: constraints.maxWidth, minHeight: constraints.minHeight, maxHeight: constraints.maxHeight);
  // }

  // if the model wants to expand in the vertical and has an unbounded
  // height, then set the min height to the parent height. This happens for
  // instance when a <box expand="true"/> is inside a <scroller/>. Normally the
  // expand would be set to false in the view. This ensures the widget is at least as
  // high as the first parent with a constrained height.
  // if (model.expandVertically && !constraints.hasBoundedHeight)
  // {
  //   constraints = BoxConstraints(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth, minHeight: parentHeight, maxHeight: constraints.maxHeight);
  // }

  // visible?
  if (!model.visible) {
    constraints = const BoxConstraints(
        minWidth: 0, maxWidth: 0, minHeight: 0, maxHeight: 0);
  }

  // normalize
  return constraints.normalize();
}