B4J Tutorial See whether (and where) circles intersect

Sub FindIntersectionPoints(x1 As Double, y1 As Double, r1 As Double, x2 As Double, y2 As Double, r2 As Double) As List
    Dim result As List
    result.Initialize
 
    Dim d As Double = Sqrt(Power(x2 - x1, 2) + Power(y2 - y1, 2))
 
    ' Check if circles intersect
    If d > r1 + r2 Or d < Abs(r1 - r2) Then
        Log("No intersection points.")
        Return result
    End If

    ' Calculate a and h
    Dim a As Double = (Power(r1, 2) - Power(r2, 2) + Power(d, 2)) / (2 * d)
    Dim h As Double = Sqrt(Power(r1, 2) - Power(a, 2))
 
    ' Calculate the base point on the line between the circles' centers
    Dim x3 As Double = x1 + a * (x2 - x1) / d
    Dim y3 As Double = y1 + a * (y2 - y1) / d
 
    ' Calculate the two intersection points
    Dim x4_1 As Double = x3 + h * (y2 - y1) / d
    Dim y4_1 As Double = y3 - h * (x2 - x1) / d
 
    Dim x4_2 As Double = x3 - h * (y2 - y1) / d
    Dim y4_2 As Double = y3 + h * (x2 - x1) / d
 
    ' Add the points to the result list
    result.Add(CreateMap("x" : x4_1, "y" : y4_1))
    result.Add(CreateMap("x" : x4_2, "y" : y4_2))
 
    Return result
End Sub

Sub DrawIntersections
    Dim x1 As Double = 100, y1 As Double = 100, r1 As Double = 75
    Dim x2 As Double = 150, y2 As Double = 100, r2 As Double = 75
    Dim intersections As List = FindIntersectionPoints(x1, y1, r1, x2, y2, r2)
 
    Dim cvs As B4XCanvas
    cvs.Initialize(mainForm.rootPane)
    cvs.DrawCircle(x1, y1, r1, xui.Color_Blue, False, 2dip)
    cvs.DrawCircle(x2, y2, r2, xui.Color_Red, False, 2dip)
 
    For Each p As Map In intersections
        Dim px As Double = p.Get("x")
        Dim py As Double = p.Get("y")
        cvs.DrawCircle(px, py, 5dip, xui.Color_Green, True, 1dip)
    Next
 
    cvs.Refresh
End Sub