ProRealAlgos
Graphical/probuilder

DRAWHLINE

DRAWHLINE in ProBuilder draws a horizontal line across the chart at a given price, with an optional COLOURED colour and transparency. Syntax and examples.

Syntax

probuilder
DRAWHLINE(y1) COLOURED(R, G, B, a)

Parameters

NameTypeDefaultDescription
y1pricerequiredThe price level at which the horizontal line is drawn.
R, G, Bintegerplatform defaultOptional COLOURED red, green and blue components, 0 to 255.
ainteger255Optional alpha (transparency), 0 fully transparent to 255 fully opaque.

How it works

DRAWHLINE runs inside a ProBuilder indicator. It draws a single horizontal line that spans the visible chart at the price y1. Only a y coordinate is needed, since a horizontal line has no start or end bar. This makes it convenient for marking levels such as a recent high, a recent low, or a fixed threshold.

The optional COLOURED clause sets the colour and transparency. Because the line covers the whole chart width, drawing it once is enough, so scripts commonly set DEFPARAM DrawOnLastBarOnly = true to avoid redrawing it on every historical bar.

Examples

Example 1, Highest and lowest of the last 15 bars (Indicator)

probuilder
// Draw the recent high in green and the recent low in red
DEFPARAM DrawOnLastBarOnly = true
hh = Highest[15](high)
ll = Lowest[15](low)
DRAWHLINE(hh) COLOURED(0, 200, 0)
DRAWHLINE(ll) COLOURED(200, 0, 0)
RETURN

Two horizontal lines mark the top and bottom of the recent range.

Example 2, A fixed round-number level (Indicator)

probuilder
// A grey reference line at a fixed price
DEFPARAM DrawOnLastBarOnly = true
level = 15000
DRAWHLINE(level) COLOURED(128, 128, 128, 180)
RETURN

A single line marks a static price of interest, at partial opacity so it sits behind the bars.

Example 3, Session open marker with a label (Indicator)

probuilder
// Horizontal line at the current open, annotated with text
DEFPARAM DrawOnLastBarOnly = true
DRAWHLINE(open) COLOURED(0, 100, 255)
DRAWTEXT("open", BarIndex, open) COLOURED(0, 100, 255)
RETURN

DRAWHLINE sets the level and DRAWTEXT names it.

Common errors and gotchas

  • Indicator only. DRAWHLINE has no effect in ProScreener, ProOrder or ProBacktest. Keep it in a ProBuilder indicator.
  • One argument only. It takes a single price y1. For a line between two arbitrary points use DRAWLINE or DRAWSEGMENT.
  • Redraw cost. Without DrawOnLastBarOnly = true, the line is redrawn on every bar. Set it once at the top of the script.
  • Vertical counterpart. For a vertical marker at a bar index, use DRAWVLINE instead.
  • DRAWVLINE, a vertical line at one bar index, the counterpart of this instruction.
  • DRAWLINE, a line between two arbitrary points.
  • DRAWSEGMENT, a segment between two points.
  • COLOURED, sets colour and transparency.
  • DrawOnLastBarOnly, restricts drawing to the last bar for performance.
  • Highest, supplies a recent high to mark.
  • Lowest, supplies a recent low to mark.
  • DRAWTEXT, labels the level with text.