Lines and boxes

Introduction

Pine Script™ facilitates drawing lines, boxes, and other geometric formations from code using the line, box, and polyline types. These types provide utility for programmatically drawing support and resistance levels, trend lines, price ranges, and other custom formations on a chart.

Unlike plots, the flexibility of these types makes them particularly well-suited for visualizing current calculated data at virtually any available point on the chart, irrespective of the chart bar the script executes on.

Lines, boxes, and polylines are objects, like labels, tables, and other special types. Scripts reference objects of these types using IDs, which act like pointers. As with other objects, line, box, and polyline IDs are qualified as “series” values, and all functions that manage these objects accept “series” arguments.

Lines drawn by a script may be vertical, horizontal, or angled. Boxes are always rectangular. Polylines sequentially connect multiple vertical, horizontal, angled, or curved line segments. Although all of these drawing types have different characteristics, they do have some things in common:

• Lines, boxes, and polylines can have coordinates at any available location on the chart, including ones at future times beyond the last chart bar.
• Objects of these types can use chart.point instances to set their coordinates.
• The x-coordinates of each object can be bar index or time values, depending on their specified xloc property.
• Each object can have one of multiple predefined line styles.
• Scripts can call the functions that manage these objects from within the scopes of loops and conditional structures, allowing iterative and conditional control of their drawings.
• There are limits on the number of these objects that a script can reference and display on the chart. A single script instance can display up to 500 lines, 500 boxes, and 100 polylines. Users can specify the maximum number allowed for each type via the max_lines_count, max_boxes_count, and max_polylines_count parameters of the script’s indicator() or strategy() declaration statement. If unspecified, the default is ~50. As with label and table types, lines, boxes, and polylines utilize a garbage collection mechanism that deletes the oldest objects on the chart when the total number of drawings exceeds the script’s limit.

Lines

The built-ins in the line.* namespace control the creation and management of line objects:

• The line.new() function creates a new line.
• The line.set_*() functions modify line properties.
• The line.get_*() functions retrieve values from a line instance.
• The line.copy() function clones a line instance.
• The line.delete() function deletes an existing line instance.
• The line.all variable references a read-only array containing the IDs of all lines displayed by the script. The array’s size depends on the max_lines_count of the indicator() or strategy() declaration statement and the number of lines the script has drawn.

Scripts can call line.set_*(), line.get_*(), line.copy(), and line.delete() built-ins as functions or methods.

Creating lines

The line.new() function creates a new line instance to display on the chart. It has the following signatures:

line.new(first_point, second_point, xloc, extend, color, style, width, force_overlay) → series line

line.new(x1, y1, x2, y2, xloc, extend, color, style, width, force_overlay) → series line

The first overload of this function contains the first_point and second_point parameters. The first_point is a chart.point representing the start of the line, and the second_point is a chart.point representing the line’s end. The function copies the information from these chart points to determine the line’s coordinates. Whether it uses the index or time fields from the first_point and second_point as x-coordinates depends on the function’s xloc value.

The second overload specifies x1, y1, x2, and y2 values independently, where x1 and x2 are int values representing the starting and ending x-coordinates of the line, and y1 and y2 are float values representing the y-coordinates. Whether the line considers the x values as bar indices or timestamps depends on the xloc value in the function call.

Both overloads share the same additional parameters:

xloc

Controls whether the x-coordinates of the new line use bar index or time values. Its default value is xloc.bar_index.

When calling the first overload, using an xloc value of xloc.bar_index tells the function to use the index fields of the first_point and second_point, and a value of xloc.bar_time tells the function to use the time fields of the points.

When calling the second overload, an xloc value of xloc.bar_index prompts the function to treat the x1 and x2 arguments as bar index values. When using xloc.bar_time, the function will treat x1 and x2 as time values.

When the specified x-coordinates represent bar index values, it’s important to note that the minimum x-coordinate allowed is bar_index - 9999. For larger offsets, one can use xloc.bar_time.

extend

Determines whether the drawn line will infinitely extend beyond its defined start and end coordinates. It accepts one of the following values: extend.left, extend.right, extend.both, or extend.none (default).

color

Specifies the color of the line drawing. The default is color.blue.

style

Specifies the line’s style, which can be any of the options listed in this page’s Line styles section. The default value is line.style_solid.

width

Controls the width of the line, in pixels. The default value is 1.

force_overlay

If true, the drawing will display on the main chart pane, even when the script occupies a separate pane. Optional. The default is false.

The example below demonstrates how one can draw lines in their simplest form. This script draws a new vertical line connecting the open and close prices at the horizontal center of each chart bar:

Note that:

• If the firstPoint and secondPoint reference identical coordinates, the script will not display a line since there is no distance between them to draw. However, the line ID will still exist.
• The script will only display approximately the last 50 lines on the chart, as it does not have a specified max_lines_count in the indicator() function call. Line drawings persist on the chart until deleted using line.delete() or removed by the garbage collector.
• The script redraws the line on the open chart bar (i.e., the bar with an orange background highlight) until it closes. After the bar closes, it will no longer update the drawing.

Let’s look at a more involved example. This script uses the previous bar’s hl2 price and the current bar’s high and low prices to draw a fan with a user-specified number of lines projecting a range of hypothetical price values for the following chart bar. It calls line.new() within a for loop to create linesPerBar lines on each bar:

Note that:

• We’ve included max_lines_count = 500 in the indicator() function call, meaning the script preserves up to 500 lines on the chart.
• Each line.new() call copies the information from the chart.point referenced by the firstPoint and secondPoint variables. As such, the script can change the price field of the secondPoint on each loop iteration without affecting the y-coordinates in other lines.

Modifying lines

The line.* namespace contains multiple setter functions that modify the properties of line instances:

• line.set_first_point() and line.set_second_point() respectively update the start and end points of the id line using information from the specified point.
• line.set_x1() and line.set_x2() set one of the x-coordinates of the id line to a new x value, which can represent a bar index or time value depending on the line’s xloc property.
• line.set_y1() and line.set_y2() set one of the y-coordinates of the id line to a new y value.
• line.set_xy1() and line.set_xy2() update one of the id line’s points with new x and y values.
• line.set_xloc() sets the xloc of the id line and updates both of its x-coordinates with new x1 and x2 values.
• line.set_extend() sets the extend property of the id line.
• line.set_color() updates the id line’s color value.
• line.set_style() changes the style of the id line.
• line.set_width() sets the width of the id line.

All setter functions directly modify the id line passed into the call and do not return any value. Each setter function accepts “series” arguments, as a script can change a line’s properties throughout its execution.

The following example draws lines connecting the opening price of a timeframe to its closing price. The script uses the var keyword to declare the periodLine and the variables that reference chart.point values (openPoint and closePoint) only on the first chart bar, and it assigns new values to these variables over its execution. After detecting a change on the timeframe, it sets the color of the existing periodLine using line.set_color(), creates new values for the openPoint and closePoint using chart.point.now(), then assigns a new line using those points to the periodLine.

On other bars where the periodLine value is not na, the script assigns a new chart.point to the closePoint, then uses line.set_second_point() and line.set_color() as methods to update the line’s properties:

Note that:

• Each line drawing in this example uses the line.style_arrow_right style. See the Line styles section below for an overview of all available style settings.

Line styles

Users can control the style of their scripts’ line drawings by passing one of the following variables as the style argument in their line.new() or line.set_style() function calls:

Argument	Line
line.style_solid
line.style_dotted
line.style_dashed
line.style_arrow_left
line.style_arrow_right
line.style_arrow_both

Note that:

• Polylines can also use any of these variables as their line_style value. See the Creating polylines section of this page.

Reading line values

The line.* namespace includes getter functions, which allow a script to retrieve values from a line object for further use:

• line.get_x1() and line.get_x2() respectively get the first and second x-coordinate from the id line. Whether the value returned represents a bar index or time value depends on the line’s xloc property.
• line.get_y1() and line.get_y2() respectively get the id line’s first and second y-coordinate.
• line.get_price() retrieves the price (y-coordinate) from a line id at a specified x value, including at bar indices outside the line’s start and end points. This function is only compatible with lines that use xloc.bar_index as the xloc value.

The script below draws a new line upon the onset of a rising or falling price pattern forming over length bars. It uses the var keyword to declare the directionLine variable on the first chart bar. The ID assigned to the directionLine persists over subsequent bars until the newDirection condition occurs, in which case the script assigns a new line to the variable.

On every bar, the script calls the line.get_y2(), line.get_y1(), line.get_x2(), and line.get_x1() getters as methods to retrieve values from the current directionLine and calculate its slope, which it uses to determine the color of each drawing and plot. It retrieves extended values of the directionLine from beyond its second point using line.get_price() and plots them on the chart:

Note that:

• This example calls the second overload of the line.new() function, which uses x1, y1, x2, and y2 parameters to define the start and end points of the line. The x1 value is length bars behind the current bar_index, and the y1 value is the hlc3 value at that index. The x2 and y2 in the function call use the current bar’s bar_index and hlc3 values.
• The line.get_price() function call treats the directionLine as though it extends infinitely, regardless of its extend property.
• The script only displays approximately the last 50 lines on the chart, but the plot of extrapolated values spans throughout the chart’s history.

Cloning lines

Scripts can clone a line id and all its properties with the line.copy() function. Any changes to the copied line instance do not affect the original.

For example, this script creates a horizontal line at the the bar’s open price once every length bars, which it assigns to a mainLine variable. On all other bars, it creates a copiedLine using line.copy() and calls line.set_*() functions to modify its properties. As we see below, altering the copiedLine does not affect the mainLine in any way:

Note that:

• The index field of the secondPoint is length bars beyond the current bar_index. Since the maximum x-coordinate allowed with xloc.bar_index is bar_index + 500, we’ve set the maxval of the length input to 500.

Deleting lines

To delete a line id drawn by a script, use the line.delete() function. This function removes the line instance from the script and its drawing on the chart.

Deleting line instances is often handy when one wants to only keep a specific number of lines on the chart at any given time or conditionally remove drawings as a chart progresses.

For example, this script draws a horizontal line with the extend.right property whenever an RSI crosses its EMA.

The script stores all line IDs in a lines array that it uses as a queue to only display the last numberOfLines on the chart. When the size of the array exceeds the specified numberOfLines, the script removes the array’s oldest line ID using array.shift() and deletes it with line.delete():

Note that:

• We declared a MAX_LINES_COUNT variable with the “const int” qualified type, which the script uses as the max_lines_count in the indicator() function and the maxval of the input.int() assigned to the numberOfLines variable.
• This example uses the second overload of the line.new() function, which specifies x1, y1, x2, and y2 coordinates independently.

Filling the space between lines

Scripts can fill the space between two line drawings by creating a linefill object that references them with the linefill.new() function. Linefills automatically determine their fill boundaries using the properties from the line1 and line2 IDs that they reference.

For example, this script calculates a simple linear regression channel. On the first chart bar, the script declares the basisLine, upperLine, and lowerLine variables to reference the channel’s line IDs, then it makes two linefill.new() calls to create linefill objects that fill the upper and lower portions of the channel. The first linefill fills the space between the basisLine and the upperLine, and the second fills the space between the basisLine and lowerLine.

The script updates the coordinates of the lines across subsequent bars. However, notice that the script never needs to update the linefills declared on the first bar. They automatically update their fill regions based on the coordinates of their assigned lines:

To learn more about the linefill type, see this section of the Fills page.

Boxes

The built-ins in the box.* namespace create and manage box objects:

• The box.new() function creates a new box.
• The box.set_*() functions modify box properties.
• The box.get_*() functions retrieve values from a box instance.
• The box.copy() function clones a box instance.
• The box.delete() function deletes a box instance.
• The box.all variable references a read-only array containing the IDs of all boxes displayed by the script. The array’s size depends on the max_boxes_count of the indicator() or strategy() declaration statement and the number of boxes the script has drawn.

As with lines, users can call box.set_*(), box.get_*(), box.copy(), and box.delete() built-ins as functions or methods.

Creating boxes

The box.new() function creates a new box object to display on the chart. It has the following signatures:

box.new(top_left, bottom_right, border_color, border_width, border_style, extend, xloc, bgcolor, text, text_size, text_color, text_halign, text_valign, text_wrap, text_font_family, force_overlay, text_formatting) → series box

box.new(left, top, right, bottom, border_color, border_width, border_style, extend, xloc, bgcolor, text, text_size, text_color, text_halign, text_valign, text_wrap, text_font_family, force_overlay, text_formatting) → series box

This function’s first overload includes the top_left and bottom_right parameters, which accept chart.point objects representing the top-left and bottom-right corners of the box, respectively. The function copies the information from these chart points to set the coordinates of the box’s corners. Whether it uses the index or time fields of the top_left and bottom_right points as x-coordinates depends on the function’s xloc value.

The second overload specifies left, top, right, and bottom edges of the box. The left and right parameters accept int values specifying the box’s left and right x-coordinates, which can be bar index or time values depending on the xloc value in the function call. The top and bottom parameters accept float values representing the box’s top and bottom y-coordinates.

The function’s additional parameters are identical in both overloads:

border_color

Specifies the color of all four of the box’s borders. The default is color.blue.

border_width

Specifies the width of the borders, in pixels. Its default value is 1.

border_style

Specifies the style of the borders, which can be any of the options in the Box styles section of this page.

extend

Determines whether the box’s borders extend infinitely beyond the left or right x-coordinates. It accepts one of the following values: extend.left, extend.right, extend.both, or extend.none (default).

xloc

Determines whether the left and right edges of the box use bar index or time values as x-coordinates. The default is xloc.bar_index.

In the first overload, an xloc value of xloc.bar_index means that the function will use the index fields of the top_left and bottom_right chart points, and an xloc value of xloc.bar_time means that it will use their time fields.

In the second overload, using an xloc value of xloc.bar_index means the function treats the left and right values as bar indices, and xloc.bar_time means it will treat them as timestamps.

When the specified x-coordinates represent bar index values, it’s important to note that the minimum x-coordinate allowed is bar_index - 9999. For larger offsets, one can use xloc.bar_time.

bgcolor

Specifies the background color of the space inside the box. The default value is color.blue.

text

The text to display inside the box. By default, its value is an empty string.

text_size

Specifies the size of the text within the box. It accepts both “int” size values and “string” size.* constants. The “int” size can be any positive integer. The size.* constants and their equivalent “int” sizes are: size.auto (0), size.tiny (8), size.small (10), size.normal (14), size.large (20), and size.huge (36). The default value is size.auto.

text_color

Controls the color of the text. Its default is color.black.

text_halign

Specifies the horizontal alignment of the text within the box’s boundaries. It accepts one of the following: text.align_left, text.align_right, or text.align_center (default).

text_valign

Specifies the vertical alignment of the text within the box’s boundaries. It accepts one of the following: text.align_top, text.align_bottom, or text.align_center (default).

text_wrap

Determines whether the box will wrap the text within it. If its value is text.wrap_auto, the box wraps the text to ensure it does not span past its vertical borders. It also clips the wrapped text when it extends past the bottom. If the value is text.wrap_none, the box displays the text on a single line that can extend beyond its borders. The default is text.wrap_none.

text_font_family

Defines the font family of the box’s text. Using font.family_default displays the box’s text with the system’s default font. The font.family_monospace displays the text in a monospace format. The default value is font.family_default.

force_overlay

If true, the drawing will display on the main chart pane, even when the script occupies a separate pane. Optional. The default is false.

text_formatting

Specifies the formatting of the box’s text. Using text.format_none displays the text with no special formatting. This parameter also accepts the arguments text.format_bold or text.format_italic. Using text.format_bold + text.format_italic applies both formats together to display text that is both bold and italicized. The default value is text.format_none.

Let’s write a simple script to display boxes on a chart. The example below draws a box projecting each bar’s high and low values from the horizontal center of the current bar to the center of the next available bar.

On each bar, the script creates topLeft and bottomRight points via chart.point.now() and chart.point_from_index(), then calls box.new() to construct a new box and display it on the chart. It also highlights the background on the unconfirmed chart bar using bgcolor() to indicate that it redraws that box until the bar’s last update:

Note that:

• The bottomRight point’s index field is one bar greater than the index in the topLeft. If the x-coordinates of the corners were equal, the script would draw a vertical line at the horizontal center of each bar, resembling the example in this page’s Creating lines section.
• Similar to lines, if the topLeft and bottomRight contained identical coordinates, the box wouldn’t display on the chart since there would be no space between them to draw. However, its ID would still exist.
• This script only displays approximately the last 50 boxes on the chart, as we have not specified a max_boxes_count in the indicator() function call.

Modifying boxes

Multiple setter functions exist in the box.* namespace, allowing scripts to modify the properties of box objects:

• box.set_top_left_point() and box.set_bottom_right_point() respectively update the top-left and bottom-right coordinates of the id box using information from the specified point.
• box.set_left() and box.set_right() set the left or right x-coordinate of the id box to a new left/right value, which can be a bar index or time value depending on the box’s xloc property.
• box.set_top() and box.set_bottom() set the top or bottom y-coordinate of the id box to a new top/bottom value.
• box.set_lefttop() sets the left and top coordinates of the id box, and box.set_rightbottom() sets its right and bottom coordinates.
• box.set_border_color(), box.set_border_width() and box.set_border_style() respectively update the color, width, and style of the id box’s border.
• box.set_extend() sets the horizontal extend property of the id box.
• box.set_bgcolor() sets the color of the space inside the id box to a new color.
• box.set_text(), box.set_text_size(), box.set_text_color(), box.set_text_halign(), box.set_text_valign(), box.set_text_wrap(), box.set_text_font_family(), and box.set_text_formatting() update the id box’s text-related properties.

As with setter functions in the line.* namespace, all box setters modify the id box directly without returning a value, and each setter function accepts “series” arguments.

Note that, unlike lines, the box.* namespace does not contain a setter function to modify a box’s xloc. Users must create a new box with the desired xloc setting for such cases.

This example uses boxes to visualize the ranges of upward and downward bars with the highest volume over a user-defined timeframe. When the script detects a change in the timeframe, it assigns new boxes to its upBox and downBox variables, resets its upVolume and downVolume values, and highlights the chart background.

When an upward or downward bar’s volume exceeds the upVolume or downVolume, the script updates the volume-tracking variables and calls box.set_top_left_point() and box.set_bottom_right_point() to update the upBox or downBox coordinates. The setters use the information from the chart points created with chart.point.now() and chart.point.from_time() to project that bar’s high and low values from the current time to the closing time of the timeframe:

Note that:

• The indicator() function call contains max_boxes_count = 100, meaning the script will preserve the last 100 boxes on the chart.
• We utilized both overloads of box.new() in this example. On the first bar of the timeframe, the script calls the first overload for the upBox when the bar is rising, and it calls that overload for the downBox when the bar is falling. It uses the second overload to assign a new box with na values to the other box variable on that bar.

Box styles

Users can include one of the following line.style_* variables in their box.new() or box.set_border_style() function calls to set the border styles of boxes drawn by their scripts:

Argument	Box
line.style_solid
line.style_dotted
line.style_dashed

Reading box values

The box.* namespace features getter functions that allow scripts to retrieve coordinate values from a box instance:

• box.get_left() and box.get_right() respectively get the x-coordinates of the left and right edges of the id box. Whether the value returned represents a bar index or time value depends on the box’s xloc property.
• box.get_top() and box.get_bottom() respectively get the top and bottom y-coordinates of the id box.

The example below draws boxes to visualize hypothetical price ranges over a period of length bars. At the start of each new period, it uses the average candle range multiplied by the scaleFactor input to calculate the corner points of a box centered at the hl2 price with an initialRange height. After drawing the first box, it creates numberOfBoxes - 1 new boxes inside a for loop.

Within each loop iteration, the script gets the lastBoxDrawn by retrieving the last element from the read-only box.all array, then calls box.get_top() and box.get_bottom() to get its y-coordinates. It uses these values to calculate the coordinates for a new box that’s scaleFactor times taller than the previous:

Note that:

• The indicator() function call uses max_boxes_count = 500, meaning the script can display up to 500 boxes on the chart.
• Each drawing has a right index length bars beyond the left index. Since the x-coordinates of these drawings can be up to 500 bars into the future, we’ve set the maxval of the length input to 500.
• On each new period, the script uses randomized color.rgb() values for the border_color and bgcolor of the boxes.
• Each box.new() call copies the coordinates from the chart.point objects assigned to the topLeft and bottomRight variables, which is why the script can modify their price fields on each loop iteration without affecting the other boxes.

Cloning boxes

To clone a specific box id, use box.copy(). This function copies the box and its properties. Any changes to the copied box do not affect the original.

For example, this script declares an originalBox variable on the first bar and assigns a new box to it once every length bars. On other bars, it uses box.copy() to create a copiedBox and calls box.set_*() functions to modify its properties. As shown on the chart below, these changes do not modify the originalBox:

Deleting boxes

To delete boxes drawn by a script, use box.delete(). As with *.delete() functions in other drawing namespaces, this function is handy for conditionally removing boxes or maintaining a specific number of boxes on the chart.

This example displays boxes representing periodic cumulative volume values. The script creates a new box ID and stores it in a boxes array once every length bars. If the array’s size exceeds the specified numberOfBoxes, the script removes the oldest box from the array using array.shift() and deletes it using box.delete().

On other bars, it accumulates volume over each period by modifying the top of the last box in the boxes array. The script then uses for loops to find the highestTop of all the array’s boxes and set the bgcolor of each box with a gradient color based on its box.get_top() value relative to the highestTop:

Note that:

• At the top of the code, we’ve declared a MAX_BOXES_COUNT variable with the “const int” qualified type. We use this value as the max_boxes_count in the indicator() function and the maximum possible value of the numberOfBoxes input.
• This script uses the second overload of the box.new() function, which specifies the box’s left, top, right, and bottom coordinates separately.
• We’ve included format.volume as the format argument in the indicator() call, which tells the script that the y-axis of the chart pane represents volume values. Each box also displays its top value as volume-formatted text.

Polylines

Pine Script™ polylines are advanced drawings that sequentially connect the coordinates from an array of chart.point instances using straight or curved line segments.

These powerful drawings can connect up to 10,000 points at any available location on the chart, allowing scripts to draw custom series, polygons, and other complex geometric formations that are otherwise difficult or impossible to draw using line or box objects.

The polyline.* namespace features the following built-ins for creating and managing polyline objects:

• The polyline.new() function creates a new polyline instance.
• The polyline.delete() function deletes an existing polyline instance.
• The polyline.all variable references a read-only array containing the IDs of all polylines displayed by the script. The array’s size depends on the max_polylines_count of the indicator() or strategy() declaration statement and the number of polylines drawn by the script.

Unlike lines or boxes, polylines do not have functions for modification or reading their properties. To redraw a polyline on the chart, one can delete the existing instance and create a new polyline with the desired changes.

Creating polylines

The polyline.new() function creates a new polyline instance to display on the chart. It has the following signature:

polyline.new(points, curved, closed, xloc, line_color, fill_color, line_style, line_width, force_overlay) → series polyline

The following eight parameters affect the behavior of a polyline drawing:

points

Accepts an array of chart.point objects that determine the coordinates of each point in the polyline. The drawing connects the coordinates from each element in the array sequentially, starting from the first. Whether the polyline uses the index or time field from each chart point for its x-coordinates depends on the xloc value in the function call.

curved

Specifies whether the drawing uses curved line segments to connect each chart.point in the points array. The default value is false, meaning it uses straight line segments.

closed

Controls whether the polyline will connect the last chart.point in the points array to the first, forming a closed polyline. The default value is false.

xloc

Specifies which field from each chart.point in the points array the polyline uses for its x-coordinates. When its value is xloc.bar_index, the function uses the index fields to create the polyline. When its value is xloc.bar_time, the function uses the time fields. The default value is xloc.bar_index.

line_color

Specifies the color of all line segments in the polyline drawing. The default is color.blue.

fill_color

Controls the color of the closed space filled by the polyline drawing. Its default value is na.

line_style

Specifies the style of the polyline, which can be any of the available options in the Line styles section of this page. The default is line.style_solid.

line_width

Specifies the width of the polyline, in pixels. The default value is 1.

force_overlay

If true, the drawing will display on the main chart pane, even when the script occupies a separate pane. Optional. The default is false.

This script demonstrates a simple example of drawing a polyline on the chart. It pushes a new chart.point with an alternating price value into a points array and colors the background with bgcolor() once every length bars.

On the last confirmed historical bar, the script draws a new polyline on the chart, connecting the coordinates from each chart point in the array, starting from the first:

Note that:

• This script uses only one polyline to connect each chart point from the array with straight line segments, and this drawing spans throughout the available chart data, starting from the first bar.
• While one can achieve a similar effect using lines, doing so would require a new line instance on each occurrence of the newPoint condition, and such a drawing would be limited to a maximum of 500 line segments. This single unclosed polyline drawing, on the other hand, can contain up to 9,999 line segments.

Curved drawings

Polylines can draw curves that are otherwise impossible to produce with lines or boxes. When enabling the curved parameter of the polyline.new() function, the resulting polyline interpolates nonlinear values between the coordinates from each chart.point in its array of points to generate a curvy effect.

For instance, the “Oscillating polyline” script in our previous example uses straight line segments to produce a drawing resembling a triangle wave, meaning a waveform that zig-zags between its peaks and valleys. If we set the curved parameter in the polyline.new() call from that example to true, the resulting drawing would connect the points using curved segments, producing a smooth, nonlinear shape similar to a sine wave:

Notice that in this example, the smooth curves have relatively consistent behavior, and no portion of the drawing extends past its defined coordinates, which is not always the case when drawing curved polylines. The data used to construct a polyline heavily impacts the smooth, piecewise function it interpolates between its points. In some cases, the interpolated curve can reach beyond its actual coordinates.

Let’s add some variation to the chart points in our example’s points array to demonstrate this behavior. In the version below, the script multiplies the yValue by a random value in the chart.point.now() calls.

To visualize the behavior, this script also creates a horizontal line at the price value from each chart.point in the points array, and it displays another polyline connecting the same points with straight line segments. As we see on the chart, both polylines pass through all coordinates from the points array. However, the curvy polyline occasionally reaches beyond the vertical boundaries indicated by the horizontal lines, whereas the polyline drawn using straight segments does not:

Closed shapes

Since a single polyline can contain numerous straight or curved line segments, and the closed parameter allows the drawing to connect the coordinates from the first and last chart.point in its array of points, we can use polylines to draw many different types of closed polygonal shapes.

Let’s draw some polygons in Pine. The following script periodically draws randomized polygons centered at hl2 price values.

On each occurrence of the newPolygon condition, it clears the points array, calculates the numberOfSides and rotationOffset of the new polygon drawing based on math.random() values, then uses a for loop to push numberOfSides new chart points into the array that contain stepped coordinates from an elliptical path with xScale and yScale semi-axes. The script draws the polygon by connecting each chart.point from the points array using a closed polyline with straight line segments:

Note that:

• This example shows the last ~50 polylines on the chart, as we have not specified a max_polylines_count value in the indicator() function call.
• The yScale calculation multiplies an input.float() by ta.atr(2) to adapt the vertical scale of the drawings to recent price ranges.
• The resulting polygons have a maximum width of twice the horizontal semi-axis (2 * xScale), rounded to the nearest integer. The newPolygon condition uses this value to prevent the polygon drawings from overlapping.
• The script rounds the xValue calculation to the nearest integer because the index field of a chart.point only accepts an int value, as the x-axis of the chart does not include fractional bar indices.

Deleting polylines

To delete a specific polyline id, use polyline.delete(). This function removes the polyline object from the script and its drawing on the chart.

As with other drawing objects, we can use polyline.delete() to maintain a specific number of polyline drawings or conditionally remove drawings from a chart.

For example, the script below periodically draws approximate arithmetic spirals and stores their polyline IDs in an array, which it uses as a queue to manage the number of drawings it displays.

When the newSpiral condition occurs, the script creates a points array and adds chart points within a for loop. On each loop iteration, it calls the spiralPoint() user-defined function to create a new chart.point containing stepped values from an elliptical path that grows with respect to the angle. The script then creates a randomly colored curved polyline connecting the coordinates from the points and pushes its ID into the polylines array.

When the array’s size exceeds the specified numberOfSpirals, the script removes the oldest polyline using array.shift() and deletes the object using polyline.delete():

Note that:

• We declared a MAX_POLYLINES_COUNT global variable with a constant value of 100. The script uses this constant as the max_polylines_count value in the indicator() function and the maxval of the numberOfSpirals input.
• As with our “N-sided polygons” example in the previous section, we round the calculation of x-coordinates to the nearest integer since the index field of a chart.point can only accept an int value.
• Despite the smooth appearance of the drawings, each polyline’s points array only contains four chart.point objects per spiral rotation. Since the polyline.new() call includes curved = true, each polyline uses smooth curves to connect their points, producing a visual approximation of the spiral’s actual curvature.
• The width of each spiral is approximately 4 * math.pi * rotations * xScale, rounded to the nearest integer. We use this value in the newSpiral condition to space each drawing and prevent overlaps.

Redrawing polylines

It may be desirable in some cases to change a polyline drawing throughout a script’s execution. While the polyline.* namespace does not contain built-in setter functions, we can redraw polylines referenced by variables or collections by deleting the existing polylines and assigning new instances with the desired changes.

The following example uses polyline.delete() and polyline.new() calls to update the value of a polyline variable.

This script draws closed polylines that connect the open, high, low, and close points of periods containing length bars. It creates a currentDrawing variable on the first bar and assigns a polyline ID to it on every chart bar. It uses the openPoint, highPoint, lowPoint, and closePoint variables to reference chart points that track the period’s developing OHLC values. As new values emerge, the script assigns new chart.point objects to the variables, collects them in an array using array.from, then creates a new polyline connecting the coordinates from the array’s points and assigns it to the currentDrawing.

When the newPeriod condition is false (i.e., the current period is not complete), the script deletes the polyline referenced by the currentDrawing before creating a new one, resulting in a dynamic drawing that changes over the developing period:

Realtime behavior

Lines, boxes, and polylines are subject to both commit and rollback actions, which affect the behavior of a script when it executes on a realtime bar. See the page on Pine Script™‘s Execution model.

This script demonstrates the effect of rollback when it executes on the realtime, unconfirmed chart bar:

The line.new() call in this example creates a new line ID on each iteration when values change on the unconfirmed bar. The script automatically deletes the objects created on each change in that bar because of the rollback before each iteration. It only commits the last line created before the bar closes, and that line instance is the one that persists on the confirmed bar.

Limitations

Total number of objects

Lines, boxes, and polylines consume server resources, which is why there are limits on the total number of drawings per script. When a script creates more drawing objects than the allowed limit, the Pine Script™ runtime automatically deletes the oldest ones in a process referred to as garbage collection.

A single script can contain up to 500 lines, 500 boxes, and 100 polylines. Users can control the garbage collection limits by specifying the max_lines_count, max_boxes_count, and max_polylines_count values in their script’s indicator() or strategy() declaration statement.

This script demonstrates how garbage collection works in Pine. It creates a new line, box, and polyline on each chart bar. We haven’t specified values for the max_lines_count, max_boxes_count, or max_polylines_count parameters in the indicator() function call, so the script will maintain the most recent ~50 lines, boxes, and polylines on the chart, as this is the default setting for each parameter:

Note that:

• We’ve used TradingView’s “Measure” drawing tool to measure the number of bars covered by the script’s drawing objects.

Future references with `xloc.bar_index`

Objects positioned using xloc.bar_index can contain x-coordinates no further than 500 bars into the future.

Other contexts

Scripts cannot use lines, boxes, or polylines in request.*() functions. Instances of these types can use the values from request.*() calls, but scripts can only create and draw them in the chart’s context.

This limitation is also why drawing objects will not work when using the timeframe parameter in the indicator() declaration statement.

Historical buffer and `max_bars_back`

Using barstate.isrealtime in combination with drawings may sometimes produce unexpected results. For example, the intention of this script is to ignore all historical bars and draw horizontal lines spanning 300 bars back on realtime bars:

However, it will fail at runtime and raise an error. The script fails because it cannot determine the buffer size for historical values of the underlying time series. Although the code doesn’t contain the built-in time variable, the built-in bar_index uses the time series in its inner workings. Therefore, accessing the value of the bar_index from 300 bars back requires the history buffer of the time series to be at least 300 bars.

Pine Script™ includes a mechanism that detects the required historical buffer size automatically in most cases. It works by letting the script access historical values any number of bars back for a limited duration. In this script’s case, using barstate.isrealtime to control the drawing of lines prevents it from accessing the historical series, so it cannot infer the required historical buffer size, and the script fails.

The simple solution to this issue is to use the max_bars_back() function to explicitly define the historical buffer of the time series before evaluating the conditional structure:

Such issues can be confusing, but they’re quite rare. The Pine Script™ team hopes to eliminate them over time.