/// <summary>
/// Updates a rectangle that fills the header in which a label can be placed.
/// </summary>
/// <param name="node">The group node.</param>
/// <param name="header">The visual to update.</param>
/// <returns>The updated header rectangle.</returns>
private static Rectangle RenderHeader(INode node, Rectangle header)
{
// the lower corner is the anchor of the label.
var anchorX = node.Layout.X;
var anchorY = node.Layout.GetMaxY();
// Calculate the box of the label. It uses the whole width of the node.
var width = node.Layout.Width;
var headerHeight = HeaderHeight;
var firstLabel = node.Labels.FirstOrDefault();
if (firstLabel != null)
{
headerHeight = Math.Max(headerHeight, firstLabel.GetLayout().Height);
}
var oldCache = header.GetRenderDataCache <HeaderRenderData>();
var newCache = new HeaderRenderData {
AnchorX = anchorX, AnchorY = anchorY, Width = width, HeaderHeight = headerHeight
};
if (!newCache.Equals(oldCache))
{
header.SetRenderDataCache(newCache);
header.SetCanvasArrangeRect(new Rect(anchorX, anchorY - headerHeight, width, headerHeight));
}
return(header);
}
private bool Equals(HeaderRenderData other)
{
return(other.AnchorX == AnchorX && other.AnchorY == AnchorY && other.Width == Width && other.HeaderHeight == HeaderHeight);
}
