Trading Sessions - Built-in Indicator Guide

Shades chart bars that fall in the pre-market and after-hours trading sessions; transparent on daily or higher timeframes.

Overview

This indicator visualizes trading session structure by painting chart bars that belong to the pre-market session and the after-hours (post-market) session. It is meant for intraday charts where session boundaries matter; on daily and higher timeframes it intentionally draws nothing.

The pre-market session is shown with a translucent yellow background and the after-hours session with a translucent blue background. The after-hours block can have a left outline that marks the start of a new trading period. Regular trading hours remain unshaded.

How it works

1. If self.time_frame is daily or higher, return transparent backgrounds so no session shading is drawn.
2. For intraday timeframes, create a plot.Background() for the pre-market session.
3. If self.time[0] is not inside self.trading_session.pre_market, set its color to color.TRANSPARENT, otherwise keep the decorator default.
4. Create a second plot.Background() for the after-hours session and apply the same membership check with self.trading_session.after_hours.
5. For the after-hours background, set outline_left to true only when the previous timestamp exists and is_same_period sees a different period.
6. Return both background objects; the order matches the two @plot.background decorators.

Logic flow

flowchart TD
    A["Start Main"] --> B{"Timeframe >= 1 day?"}
    B -- "Yes" --> C["Return transparent backgrounds"]
    B -- "No" --> D["Build default pre_market and after_hours backgrounds"]
    D --> E{"time[0] in pre_market?"}
    E -- "No" --> F["pre_market color = transparent"]
    E -- "Yes" --> G["Keep default pre-market color"]
    G --> H{"time[0] in after_hours?"}
    F --> H
    H -- "No" --> I["after_hours color = transparent"]
    H -- "Yes" --> J["Keep default after-hours color"]
    I --> K["Set outline_left from previous bar period"]
    J --> K
    K --> L["Return both backgrounds"]

Code walkthrough

Indicator declaration and daily guard

Lines 6-11 of Trading Sessions.indie5:

@indicator('Trading Sessions', overlay_main_pane=True)
@plot.background(color=color.YELLOW(0.07), title='Pre-market session')
@plot.background(color=color.BLUE(0.07), outline_color=color.BLUE, title='Post-market session')
def Main(self):
    if self.time_frame >= TimeFrame(1, time_frame_unit.DAY):
        return plot.Background(color=color.TRANSPARENT), plot.Background(color=color.TRANSPARENT)

The @indicator decorator registers the script as an overlay in the main pane. Two @plot.background decorators create two background plots with default colors and settings titles. The first check skips all work on daily or higher timeframes by returning transparent backgrounds.

Per-session color decisions

Lines 13-19 of Trading Sessions.indie5:

    pre_market_background = plot.Background()
    if self.time[0] not in self.trading_session.pre_market:
        pre_market_background.color = color.TRANSPARENT

    after_hours_background = plot.Background()
    if self.time[0] not in self.trading_session.after_hours:
        after_hours_background.color = color.TRANSPARENT

New plot.Background() objects are created for each bar. Each one starts with the defaults from the decorator. If the current bar time is not in pre_market or after_hours, the corresponding color is set to color.TRANSPARENT, so only bars inside those sessions get a visible fill.

Left outline and return

Lines 21-26 of Trading Sessions.indie5:

    after_hours_background.outline_left = (
        not isnan(self.time[1]) and
        not self.trading_session.is_same_period(self.time[0], self.time[1])
    )

    return pre_market_background, after_hours_background

outline_left is assigned only for the after-hours background. It becomes true when the previous timestamp exists and is_same_period reports the two timestamps are in different periods, drawing a vertical line at the left edge of the background. The returned tuple matches the order of the @plot.background decorators.

Reading the chart

• Yellow translucent background: bars whose timestamp is in self.trading_session.pre_market.
• Blue translucent background: bars whose timestamp is in self.trading_session.after_hours.
• A blue outline on the left side of the after-hours block marks a bar that starts a new period relative to the previous bar.
• Transparent background means either the timeframe is daily or higher, or the bar is outside the corresponding session; regular market hours are not colored.

Implementation notes

• On daily or higher timeframes the indicator is a no-op because both backgrounds are transparent.
• self.time[1] is used only to compute outline_left; it is guarded with isnan to handle missing previous timestamps.
• The @plot.background decorators supply default colors and titles; Main overrides color only for bars outside the session.
• No explicit regular-session background exists; regular hours are the absence of both pre-market and after-hours shading.

FAQ

On which timeframes does this indicator draw anything?

On intraday timeframes only. The code checks self.time_frame >= TimeFrame(1, time_frame_unit.DAY) and returns transparent backgrounds on daily or higher.

How do I change the session colors?

Edit the color arguments in the @plot.background decorators, for example color.YELLOW(0.07) to another color and alpha. The title parameter there controls the name shown in the settings UI.

What is the vertical outline on the left of the after-hours background?

It is outline_left, set when self.time[1] exists and self.trading_session.is_same_period(self.time[0], self.time[1]) is false, meaning the current bar starts a new trading period relative to the previous bar.

Full source code

Indie Script v5, the built-in indicator as shipped with TakeProfit. Add it from the indicators menu or copy the code into the platform’s script editor.

# indie:lang_version = 5
from math import isnan
from indie import indicator, plot, color, TimeFrame, time_frame_unit


@indicator('Trading Sessions', overlay_main_pane=True)
@plot.background(color=color.YELLOW(0.07), title='Pre-market session')
@plot.background(color=color.BLUE(0.07), outline_color=color.BLUE, title='Post-market session')
def Main(self):
    if self.time_frame >= TimeFrame(1, time_frame_unit.DAY):
        return plot.Background(color=color.TRANSPARENT), plot.Background(color=color.TRANSPARENT)

    pre_market_background = plot.Background()
    if self.time[0] not in self.trading_session.pre_market:
        pre_market_background.color = color.TRANSPARENT

    after_hours_background = plot.Background()
    if self.time[0] not in self.trading_session.after_hours:
        after_hours_background.color = color.TRANSPARENT

    after_hours_background.outline_left = (
        not isnan(self.time[1]) and
        not self.trading_session.is_same_period(self.time[0], self.time[1])
    )

    return pre_market_background, after_hours_background