Gives the Delta values and distance between 2 points. If the SHIFT key is pressed, the Delta value begin on coordinate 0,0,0 to point clicked (the coordinate 0,0,0 is displayed in red).

Delta_XYZ

# -*- coding: utf-8 -*-
#Delta x y z Click Q to quit
#
#OS: Windows 10 (10.0)
#Word size of OS: 64-bit
#Word size of FreeCAD: 64-bit
#Version: 0.19.22808 (Git)
#Build type: Release
#Branch: master
#Hash: 72eb41b24f12b572d55081042160954b93f4614c
#Python version: 3.6.8
#Qt version: 5.12.1
#Coin version: 4.0.0a
#OCC version: 7.3.0
#Locale: French/Mars(fr_Ma)
#
__title__   = "Delta_XYZ"
__author__  = "Mario52"
__url__     = "https://www.freecadweb.org/wiki/Main_Page"
__Wiki__    = "https://wiki.freecadweb.org/Macro_Delta_xyz"
__version__ = "00.02"
__date__    = "2020/10/23"    #YYYY/MM/DD

import Draft, Part
import math
from FreeCAD import Base
import FreeCAD, FreeCADGui
App = FreeCAD
Gui = FreeCADGui

global positionX1 ;positionX1 = 0.0
global positionY1 ;positionY1 = 0.0
global positionZ1 ;positionZ1 = 0.0
global positionX2 ;positionX2 = 0.0
global positionY2 ;positionY2 = 0.0
global positionZ2 ;positionZ2 = 0.0
global pas        ;pas        = 0

global setArrondi                    # round value
global switchResident                # switch resident 0=not resident, 1=stay resident
global switchDecimalsPref            # switch unit preference or not

#### Configuration begin      #### 
#### NOT MODIFY THE CODE HERE ####
#### for modify : go to : FreeCAD >Menu >Tools >Edit parameters... >BaseApp/Preferences/Macros/FCMmacros/Delta_XYZ ####
##
FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).SetString("Version", __version__ + " (" + __date__ + ")")
##
switchResident = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).GetBool("switchResident")   # switch Resident or not
if switchResident == False:
    FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).SetBool("switchResident", switchResident)# switch Resident or not : 0 = Not Resident 1 = Resident
##
switchDecimalsPref = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).GetBool("switchDecimalsPref")   # switch unit preference or not
if switchDecimalsPref == True:
    setArrondi = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Units").GetInt("Decimals")    # unit in preferences
else:
    FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).SetBool("switchDecimalsPref", switchDecimalsPref)# 
    setArrondi = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).GetInt("setArrondi")
    if setArrondi < 1:
        FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).SetInt("setArrondi", 3) # setArrondi
        setArrondi = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Macros/FCMmacros/" + __title__).GetInt("setArrondi")

##
####Configuration###################################################################################################################

## Tool Draft def : sub, length, dist
def sub(first, other): 
	"sub(Vector,Vector) - subtracts second vector from first one"
	if isinstance(first,FreeCAD.Vector) and isinstance(other,FreeCAD.Vector):
		return FreeCAD.Vector(first.x-other.x, first.y-other.y, first.z-other.z)
def length(first):
	"lengh(Vector) - gives vector length"
	if isinstance(first,FreeCAD.Vector):
		return math.sqrt(first.x*first.x + first.y*first.y + first.z*first.z)
def dist(first, other):
	"dist(Vector,Vector) - returns the distance between both points/vectors"
	if isinstance(first,FreeCAD.Vector) and isinstance(other,FreeCAD.Vector):
		return length(sub(first,other))

import FreeCAD, FreeCADGui 

#########
doc = FreeCAD.ActiveDocument
if doc == None:
    doc = FreeCAD.newDocument("Delta x y z")
#########

##key
global i     ; i = 0   
global c     ; c = ""
global d     ; d = ""
global v     ; v = Gui.activeDocument().activeView()
global o     ; o = ""
global s     ; s = ""
global SHIFT ; SHIFT = ""
global DOWN  ; DOWN = ""
##

class ViewObserver:
    def keyPosition(self, info):
#        global i
#        global c
        global SHIFT
        global DOWN
        global s 
        global d 
        global v
        global o

        SHIFT = ""
        key = info["Key"]

        if (key.upper() == "SHIFT") and (info["ShiftDown"] == False):  #
            SHIFT = "SHIFT"
            DOWN  = "DOWN"
            key   = ""

        if key.upper() == "Q":
            FreeCADGui.Selection.removeObserver(s)                     # Uninstalls the resident function
            v.removeEventCallback("SoKeyboardEvent",d)
            App.Console.PrintMessage("____End Delta_XYZ____" + "\n")
        xx = info["Key"]

class SelObserver:
    def addSelection(self,document, object, element, position):  # Selection
        global pas
        global positionX1
        global positionY1
        global positionZ1
        global positionX2
        global positionY2
        global positionZ2
        global SHIFT
        global DOWN
        global s 
        global d 
        global v

        pas+=1
        if (SHIFT == "SHIFT") and (DOWN == "DOWN"):
            positionX1 = 0.0
            positionY1 = 0.0
            positionZ1 = 0.0
            App.Console.PrintError("Begin    : X1 "+str(positionX1)+" Y1: "+str(positionY1)+" Z1: "+str(positionZ1)+"\n")    
            pas = 2
            SHIFT = DOWN  = ""

        if pas==1:
            positionX1 = round(position[0],setArrondi)
            positionY1 = round(position[1],setArrondi)
            positionZ1 = round(position[2],setArrondi)
            App.Console.PrintMessage("Begin    : X1 "+str(positionX1)+" Y1: "+str(positionY1)+" Z1: "+str(positionZ1)+"\n")    
        else:
            positionX2 = round(position[0],setArrondi)
            positionY2 = round(position[1],setArrondi)
            positionZ2 = round(position[2],setArrondi)
            App.Console.PrintMessage("End      : X2 "+str(positionX2)+" Y2: "+str(positionY2)+" Z2: "+str(positionZ2)+"\n")    
            App.Console.PrintMessage("Delta X  : "+str(round(abs(positionX1-positionX2),setArrondi))+"\n")    
            App.Console.PrintMessage("Delta Y  : "+str(round(abs(positionY1-positionY2),setArrondi))+"\n")    
            App.Console.PrintMessage("Delta Z  : "+str(round(abs(positionZ1-positionZ2),setArrondi))+"\n")    
            v1=FreeCAD.Vector(positionX1,positionY1,positionZ1)
            v2=FreeCAD.Vector(positionX2,positionY2,positionZ2)
            distance = dist(v1,v2)
            App.Console.PrintMessage("Distance : "+ str(round(distance,setArrondi))+"\n")
            App.Console.PrintMessage("__________________________________"+"\n")
            pas=0
            if switchResident == False:
                FreeCADGui.Selection.removeObserver(s)                     # Uninstalls the resident function
                v.removeEventCallback("SoKeyboardEvent",d)                 # Uninstalls the resident function


pas = 0
s=SelObserver()
FreeCADGui.Selection.addObserver(s)          # install the function mode resident 
## key
o = ViewObserver()                           # install the function mode resident 
d = v.addEventCallback("SoKeyboardEvent",o.keyPosition)
App.Console.PrintMessage("____Begin Delta_XYZ____" + "\n")
##
FreeCAD.Console.PrintMessage("\n"+"####Configure################################################################################################" + "\n\n")
FreeCAD.Console.PrintMessage("For modify the value : go to : FreeCAD >Menu >Tools >Edit parameters... >BaseApp/Preferences/Macros/FCMmacros/Delta_XYZ"+"\n\n")
FreeCAD.Console.PrintMessage("_____switchDecimalsPref_____  ")
FreeCAD.Console.PrintError("Actual " + str(switchDecimalsPref)+"\n")
FreeCAD.Console.PrintMessage("switchDecimalsPref : True  1 : the round value takes the global preferences value "+"\n")
FreeCAD.Console.PrintMessage("                   : False 0 : the round value takes your choice "+"\n\n")
FreeCAD.Console.PrintMessage("_____setArrondi_____  ")
FreeCAD.Console.PrintError("Actual " + str(setArrondi)+"\n")
FreeCAD.Console.PrintMessage("setArrondi         : set your choice round value"+"\n")
FreeCAD.Console.PrintMessage("                   : if your choice = 0 : the round value is 3 by default "+"\n\n")
FreeCAD.Console.PrintMessage("_____switchResident_____  ")
FreeCAD.Console.PrintError("Actual " + str(switchResident)+"\n")
FreeCAD.Console.PrintMessage("switchResident     : True  1 : the macro stay resident (Type Q to quit)"+"\n")
FreeCAD.Console.PrintMessage("                   : False 0 : the macro is used on run and quit after use"+"\n")
FreeCAD.Console.PrintMessage("\n"+"####Configure end############################################################################################" + "\n")
FreeCAD.Console.PrintMessage("\n"+"####Use######################################################################################################" + "\n")
FreeCAD.Console.PrintMessage("Use : click the first point, click the second point, the data is diplayed"+"\n")
FreeCAD.Console.PrintMessage("    : press the SHIFT button click the point, the Delta is displayed with the coordinate X=0,Y=0,Z=0 to point clicked X, Y, Z"+"\n")
FreeCAD.Console.PrintMessage("    : the first coordinate X=0, Y=0, Z=0 is displayed in red"+"\n")
FreeCAD.Console.PrintMessage("####Use end#######################################################################################################" + "\n\n")
##