Voila:

//PRC_PerfectTrendLine ptl | indicator
//16.10.2017
//Nicolas @ www.prorealcode.com
//Sharing ProRealTime knowledge
//converted from MT4 version (original author mladen)
//enhanced version by Nicolas
// --- settings
SlowLength         = 7 // Slow length
SlowPipDisplace    = 0 // Slow pip displace
FastLength         = 3 // Fast length
FastPipDisplace    = 0 // Fast pip displace
// --- end of settings
 
thigh1 = Highest[SlowLength](high)+ SlowPipDisplace*pointsize
tlow1  = Lowest[SlowLength](low)- SlowPipDisplace*pointsize
thigh2 = Highest[FastLength](high)+ FastPipDisplace*pointsize
tlow2  = Lowest[FastLength](low)- FastPipDisplace*pointsize
 
if barindex>2 then
if Close>line1[1] then
line1 = tlow1
else
line1 = thigh1
endif
if Close>line2[1] then
line2 = tlow2
else
line2 = thigh2
endif
endif
 
if (Close[0]<line1[0] and Close[0]<line2[0]) then
trend =  1
endif
if (Close[0]>line1[0] and Close[0]>line2[0]) then
trend = -1
endif
if (line1[0]>line2[0] or trend[0] =  1) then
trena =  1
endif
if (line1[0]<line2[0] or trend[0] = -1) then
trena = -1
endif
if trena<>trena[1] then
if trena=1 then
x = max(line1,line2)
r=200
g=20
b=60
else
x = min(line1,line2)
r=30
g=144
b=255
endif
drawtext("●",barindex,x,Dialog,Bold,10) coloured(r,g,b)
endif
//drawbarchart(line1,line2,line1,line2) coloured(r,g,b,50)
 
return// line1 coloured(r,g,b,100) style(line,1),line2 coloured(r,g,b,100) style(line,1)

Joyeux Noël.

Roberto