Swing levels
Turn confirmed pivots into support and resistance rays with pooled lines and labels.
This example tracks the most recent confirmed swing high and swing low, extends each as a level until price trades through it, and tags it with a formatted price label. It covers entity pools, pivot confirmation lag, and str.format.
script "Swing Levels"
data chart = subscribe(data.ohlcv)
input (
pivotLen = input.int(10, title: "Pivot Strength", min: 1, max: 50)
resistanceColor = input.color(color.red, title: "Resistance")
supportColor = input.color(color.green, title: "Support")
)
state (
lines = entities.linePool(max: 2)
labels = entities.labelPool(max: 2)
highLevel: float? = null
highStart: time? = null
lowLevel: float? = null
lowStart: time? = null
)
fn drawLevel(key: string, start: time, end: time, level: float, labelY: float, tag: string, levelColor: color) {
lines.get(key).set(
x1: start,
y1: level,
x2: end,
y2: level,
color: levelColor,
width: 1.5,
style: linestyle.dashed,
)
labels.get(key).set(
x: start,
y: labelY,
text: str.format("{0} {1:.1}", tag, level),
color: levelColor,
size: 12.0,
)
}
on chart.update {
let now = (chart.time ?? time.fromUnixSeconds(0))
let last = (chart.close ?? 0.0)
// Lift labels off the level line by a volatility-scaled offset so they
// stay readable at any price scale.
let pad = (chart.atr(14) ?? 0.0) * 0.8
// A pivot confirms pivotLen bars after it happened, so anchor the level
// back at the bar that actually set it.
let pivotHigh = ta.pivotHigh(chart.high, pivotLen, pivotLen)
if pivotHigh != null {
highLevel = pivotHigh
highStart = now - time.bars(pivotLen)
}
let pivotLow = ta.pivotLow(chart.low, pivotLen, pivotLen)
if pivotLow != null {
lowLevel = pivotLow
lowStart = now - time.bars(pivotLen)
}
// Extend each level to the current bar until price trades through it.
if highLevel != null && last > (highLevel ?? 0.0) {
lines.delete("high")
labels.delete("high")
highLevel = null
} else if highLevel != null {
drawLevel("high", (highStart ?? now), now, (highLevel ?? 0.0), (highLevel ?? 0.0) + pad, "R", resistanceColor)
}
if lowLevel != null && last < (lowLevel ?? 0.0) {
lines.delete("low")
labels.delete("low")
lowLevel = null
} else if lowLevel != null {
drawLevel("low", (lowStart ?? now), now, (lowLevel ?? 0.0), (lowLevel ?? 0.0) - pad, "S", supportColor)
}
}Pivots confirm late
ta.pivotHigh(chart.high, 10, 10) only returns a value once ten bars have printed on each side of the candidate. The level is real from the pivot bar onward, so the script rewinds the anchor with now - time.bars(pivotLen) instead of starting the ray at the confirmation bar.
Entities are keyed and finite
Pools are declared with a hard max and addressed by key. lines.get("high") returns the same line every bar, so re-issuing set extends it in place. Deleting the key when price breaks the level removes the ray instead of leaving a stale artifact.
Factor the drawing, not the logic
Both sides share one drawLevel function that positions a line and its label together. The break/extend decision stays inline per side, where the asymmetry (break above vs. break below) is easiest to read.