/// <summary>
/// Quick (O(n log n)) and accurate collision detection
/// </summary>
/// <param name="labels"></param>
public static void QuickAccurateCollisionDetectionMethod(List <BaseLabel> labels)
{
// find minimum / maximum coordinates
double minX = double.MaxValue;
double maxX = double.MinValue;
double minY = double.MaxValue;
double maxY = double.MinValue;
foreach (BaseLabel l in labels)
{
var box = new ProperBox(l is PathLabel pl ? new LabelBox(pl.Location.GetBounds()) : l.Box);
if (box.Left < minX)
{
minX = box.Left;
}
if (box.Right > maxX)
{
maxX = box.Right;
}
if (box.Bottom > maxY)
{
maxY = box.Bottom;
}
if (box.Top < minY)
{
minY = box.Top;
}
}
// sort by area (highest priority first, followed by low area to maximize the amount of labels displayed)
var sortedLabels = labels.OrderByDescending(label => label.Priority).ThenBy(label =>
{
var box = label is PathLabel pl ? new LabelBox(pl.Location.GetBounds()) : label.Box;
return(box.Width * box.Height);
});
// make visible if it does not collide with other labels. Uses a quadtree and is therefore fast O(n log n)
QuadTreeNode <ProperBox> quadTree =
new QuadTreeNode <ProperBox>(minX, maxX, minY, maxY, new LabelBoxContainmentChecker(), 0, 10);
foreach (BaseLabel l in sortedLabels)
{
if (!l.Show)
{
continue;
}
var box = new ProperBox(l is PathLabel pl ? new LabelBox(pl.Location.GetBounds()) : l.Box);
if (quadTree.CollidesWithAny(box))
{
l.Show = false;
}
else
{
quadTree.Insert(box);
}
}
}
