Android Question How to draw a line specified in mm unit?

Dim r AsReflector
 r.Target = r.GetContext
 r.Target = r.RunMethod("getResources")
 r.Target = r.RunMethod("getDisplayMetrics")
xdpi=r.GetField("xdpi")                                        'is xdpi an int or a float?
ydpi=r.GetField("ydpi")

Dim imgarea As ImageView
imgarea.Initialize("")
Activity.AddView(imgarea,0dip,0dip,3*xdpi,3*ydpi)   '3x3 inches area??
Dim bm As Bitmap
bm.InitializeMutable(imgarea.Width,imgarea.Height)
Dim cv As Canvas
cv.Initialize2(bm)
cv.DrawLine(0,0,0,1.5*ydpi,Colors.White,1*xdpi)                   'vertical line - 1.5inch long - 1 inch thick??
cv.DrawLine(1*xdpi,0,1*xdpi,1.5*ydpi,Colors.White,1*xdpi)     'same as above but shifted right of 1 inch??