scaleSelectionNumeric

$canvaseditor scaleSelectionNumeric factorX factorY: manages to scale selection by factorX, factorY

obj method canvaseditor scaleSelectionNumeric {factorX factorY} {
  set factorX [double $factorX]
  set factorY [double $factorY]
  set min [min {*}[$self dots -selected cget -x]]
  set max [max {*}[$self dots -selected cget -x]]
  set centerX [/ [+ $min $max] 2.0]
  set min [min {*}[$self dots -selected cget -y]]
  set max [max {*}[$self dots -selected cget -y]]
  set centerY [/ [+ $min $max] 2.0]
  $self dots -selected storeXY
  $self selected scaleObjNumeric\
    $centerX $centerY [expr $factorX] [expr $factorY]
  $self dots -selected lines draw coords
}