Sparkline

Compact time-series display that renders a sequence of float64 values as Unicode block characters (▁▂▃▄▅▆▇█). The widget adapts to any content height: with h rows each column has $\text{h} \times 8$ discrete levels.

Constructor: NewSparkline(id, class string) *Sparkline

Methods

• Append(v float64) — add a data point; drops the oldest if at capacity
• SetValues(vs []float64) — replace the entire series (copies the slice)
• Values() []float64 — return the current series
• SetMode(m ScaleMode) — Relative or Absolute (default: Relative)
• SetMin(v float64) — lower bound for Absolute mode
• SetMax(v float64) — upper bound for Absolute mode
• SetThreshold(v float64) — values ≥ threshold use "sparkline/high" style; pass 0 to disable
• SetGradient(v bool) — when true, foreground colour blends smoothly from "sparkline" to "sparkline/high" across [threshold, max] instead of a hard cutoff; has no effect when threshold is 0
• SetCapacity(n int) — ring-buffer size; 0 = unlimited

Notes

Scale modes:

Mode	Behaviour
Relative	Tallest visible bar = █; rescaled on every render. Good for shape comparisons.
Absolute	Fixed [Min, Max] bracket. Good for showing absolute magnitude.

Multi-row rendering: the content height h is taken from the widget's layout bounds (SetHint(w, h) or whatever the parent allocates). With h rows, each column uses $\text{h} \times 8$ levels — a single ▁ at the bottom for level=0 through all rows filled with █ for level=1.

Left-padding: when the series is shorter than the widget width, the leftmost columns are rendered as blank spaces. The rightmost columns always show the most recent data.

Style keys:

Selector	When
"sparkline"	Default bar colour and background
"sparkline/high"	Bars whose raw value is ≥ the threshold