// Select the clicked point.
private void pointsPictureBox_MouseClick(object sender, MouseEventArgs e)
{
// Find the point closest to the selected point.
PointIsSelected = Root.FindPoint(e.Location, Radius, out SelectedPoint);
// Redraw.
pointsPictureBox.Refresh();
}
// Search the children to find the point closest to the target.
private bool FindPointInChildren(PointF target, float radius, out PointF resultPoint)
{
// The best point we have found so far.
resultPoint = new PointF(float.MinValue, float.MinValue);
float bestDist = float.MaxValue;
// See if the northern subtrees intersect the area of interest.
if (target.Y - radius < Ymid)
{
// See if the northwest subtree intersects the area of interest.
if (target.X - radius < Xmid)
{
// The northwest subtree does intersect the area of interest.
PointF testPoint;
if (NWchild.FindPoint(target, radius, out testPoint))
{
float dx = testPoint.X - target.X;
float dy = testPoint.Y - target.Y;
float testDist = (float)Math.Sqrt(dx * dx + dy * dy);
if ((testDist < radius) && (testDist < bestDist))
{
bestDist = testDist;
resultPoint = testPoint;
}
}
}
// See if the northeast subtree intersects the area of interest.
if (target.X + radius > Xmid)
{
// The northeast subtree does intersect the area of interest.
PointF testPoint;
if (NEchild.FindPoint(target, radius, out testPoint))
{
float dx = testPoint.X - target.X;
float dy = testPoint.Y - target.Y;
float testDist = (float)Math.Sqrt(dx * dx + dy * dy);
if ((testDist < radius) && (testDist < bestDist))
{
bestDist = testDist;
resultPoint = testPoint;
}
}
}
} // End if the northern subtrees intersect the area of interest.
// See if the southern subtrees intersect the area of interest.
if (target.Y + radius > Ymid)
{
// See if the southwest subtree intersects the area of interest.
if (target.X - radius < Xmid)
{
// The southwest subtree does intersect the area of interest.
PointF testPoint;
if (SWchild.FindPoint(target, radius, out testPoint))
{
float dx = testPoint.X - target.X;
float dy = testPoint.Y - target.Y;
float testDist = (float)Math.Sqrt(dx * dx + dy * dy);
if ((testDist < radius) && (testDist < bestDist))
{
bestDist = testDist;
resultPoint = testPoint;
}
}
}
// See if the southeast subtree intersects the area of interest.
if (target.X + radius > Xmid)
{
// The southeast subtree does intersect the area of interest.
PointF testPoint;
if (SEchild.FindPoint(target, radius, out testPoint))
{
float dx = testPoint.X - target.X;
float dy = testPoint.Y - target.Y;
float testDist = (float)Math.Sqrt(dx * dx + dy * dy);
if ((testDist < radius) && (testDist < bestDist))
{
bestDist = testDist;
resultPoint = testPoint;
}
}
}
} // End if the southern subtrees intersect the area of interest.
// Return true if we found a point.
return(bestDist < float.MaxValue);
}