How to keep drawings under the limit

A script may hold only so many drawings of each kind at once, and the oldest are deleted when it goes past the limit. To decide which ones go, keep the drawings in an array and delete the oldest yourself once the array holds more than you want.

//@lipi=2
indicator("Last 20 wide-bar boxes", overlay=true, max_boxes_count=100)
static array<box> boxes = array.new<box>(0)
if barstate.isconfirmed and high - low > talib.sma(high - low, 20) * 1.5 {
    array.push(boxes, box.new(bar_index, high, bar_index + 1, low, bgcolor=color.new(color.orange, 0.2)))
    if array.length(boxes) > 20 {
        box.delete(array.shift(boxes))
    }
}

array.push adds the newest box at the end; array.shift removes and returns the oldest, which box.delete removes from the chart. The same pattern works for line and label arrays.

The limits

Kind	Default	Set with	Highest
lines	50	`max_lines_count`	500
labels	50	`max_labels_count`	500
boxes	50	`max_boxes_count`	500
polylines	50	`max_polylines_count`	100
linefills	50	none	50
tables	9	none	9 (one per position)

These are arguments of indicator and strategy. A value above the highest is clamped, not refused; zero or a negative value gives the default. They must be constants: an input is refused. When a kind goes a few over its limit, the oldest drawings of that kind are deleted until the count is back at the limit. A line, label, box or linefill held directly in a static variable (as in How to keep one label that moves) is skipped and never trimmed, but a drawing held only inside an array is not protected. Keep your array’s cap at or below the limit, as above, so that your own deletion always comes first and the array never holds a drawing the script has already lost.

The mistake to avoid

Setting the limit from an input. The compiler says: Cannot call indicator with argument max_boxes_count=input.int(100,"Boxes"). An argument of input int type was used but a const int is expected.

//@lipi=2
indicator("Variable limit", overlay=true, max_boxes_count=input.int(100, "Boxes"))
plot(close)

The editor’s check reports it. See Lines, labels, boxes and polylines, Limits and Arrays.

Manual

Use Lipi with AI

Reference

How to keep drawings under the limit

The limits

The mistake to avoid

​The limits

​The mistake to avoid

The limits

The mistake to avoid