Session Boxes With Vol

//version=5
indicator("Session Boxes with Small Black Markers (IST)", overlay=true)

// --------------------
// Session times (IST)
// --------------------
asianStart = 0530
asianEnd = 1130

londonStart = 1230
londonEnd = 1330

nyStart = 1830
nyEnd = 1930

// --------------------
// Helpers: current bar time in IST (hhmm)
// --------------------
sessHour = hour(time, "GMT+5:30")
sessMinute = minute(time, "GMT+5:30")
sessTime = sessHour * 100 + sessMinute

inSession(startT, endT) =>
sessTime >= startT and sessTime < endT

// --------------------
// Colors
// --------------------
asiaFill = color.new(color.rgb(173, 216, 230), 81) // light blue
greyFill = color.new(color.rgb(184, 184, 184), 81) // grey

// --------------------
// Persistent variables
// --------------------
var box asiaBox = na
var label asiaLbl = na
var box londonBox = na
var box nyBox = na

// --------------------
// Utility: small vertical marker (5% of chart height)
// --------------------
createMarker() =>
rng = high - low
off = rng * 0.05
line.new(x1 = bar_index, y1 = low - off, x2 = bar_index, y2 = low + off,
xloc = xloc.bar_index, color = color.black, width = 2)

// --------------------
// Asia session
// --------------------
if inSession(asianStart, asianEnd)
if na(asiaBox)
asiaBox := box.new(left = bar_index, right = bar_index, top = high, bottom = low,
bgcolor = asiaFill, border_width = 0)
asiaLbl := label.new(x = bar_index, y = high, text = "ASIA",
style = label.style_label_left, textcolor = color.black,
color = na, size = size.normal)
createMarker() // start marker
else
box.set_right(asiaBox, bar_index)
box.set_top(asiaBox, math.max(box.get_top(asiaBox), high))
box.set_bottom(asiaBox, math.min(box.get_bottom(asiaBox), low))
label.set_x(asiaLbl, bar_index)
label.set_y(asiaLbl, box.get_top(asiaBox))
else
if not na(asiaBox)
createMarker() // end marker
asiaBox := na
asiaLbl := na

// --------------------
// London session
// --------------------
if inSession(londonStart, londonEnd)
if na(londonBox)
londonBox := box.new(left = bar_index, right = bar_index, top = high, bottom = low,
bgcolor = greyFill, border_width = 0)
createMarker() // start marker
else
box.set_right(londonBox, bar_index)
box.set_top(londonBox, math.max(box.get_top(londonBox), high))
box.set_bottom(londonBox, math.min(box.get_bottom(londonBox), low))
else
if not na(londonBox)
createMarker() // end marker
londonBox := na

// --------------------
// New York session
// --------------------
if inSession(nyStart, nyEnd)
if na(nyBox)
nyBox := box.new(left = bar_index, right = bar_index, top = high, bottom = low,
bgcolor = greyFill, border_width = 0)
createMarker() // start marker
else
box.set_right(nyBox, bar_index)
box.set_top(nyBox, math.max(box.get_top(nyBox), high))
box.set_bottom(nyBox, math.min(box.get_bottom(nyBox), low))
else
if not na(nyBox)
createMarker() // end marker
nyBox := na