Bcnk——MFB

//version=6
indicator(title = '', shorttitle = 'Bcnk——MFB', overlay = true)

length = input(title = 'Length', defval = 32)
offset = input(title = 'Offset', defval = 0)
src = input(close, title = 'Source')

// ZLSMA 计算
lsma = ta.linreg(src, length, offset)
lsma2 = ta.linreg(lsma, length, offset)
zlsma = lsma + lsma - lsma2

// 趋势方向（颜色用它控制）
isUp = zlsma >= zlsma[1]
col = isUp ? color.green : color.red

// 主线
plot(zlsma, color = col, linewidth = 3)

// ============================
// 变色（趋势方向变）就画箭头
// ============================

// 红 → 绿
upSignal = isUp and not isUp[1]

// 绿 → 红
downSignal = not isUp and isUp[1]

// 上箭头
plotshape(upSignal, title = 'Up Arrow', style = shape.arrowup, location = location.belowbar, color = color.new(color.green, 0), size = size.small)

// 下箭头
plotshape(downSignal, title = 'Down Arrow', style = shape.arrowdown, location = location.abovebar, color = color.new(color.red, 0), size = size.small)