Init

What is it?

The Init method is called once, right when your custom indicator is created or loaded onto the chart. This is where you set everything up — like naming your indicator, creating buffers, creating parameters and registering them, and more.

Syntax

public Init(): void {
    // initialization logic here
}

What MUST Be Done in `Init`

This method is like a constructor for your indicator. Here's what must happen inside:

1. Create and Register Parameters

All user-configurable parameters must be:

Declared as class-level fields using the ! syntax
Created in Init() using appropriate factory methods
Registered using this.api.RegOption() to appear in the UI

// Declare as class-level field
public period!: TOptValue_number;
public showLine!: TOptValue_bool;
public mode!: TOptValue_str;

public Init(): void {
    // Create parameters with factory methods
    this.period = this.api.createTOptValue_number(14);
    this.showLine = this.api.createTOptValue_bool(true);
    this.mode = this.api.createTOptValue_str("Simple");

    // Register parameters (required for UI visibility)
    this.api.RegOption("Period", TOptionType.INTEGER, this.period);
    this.api.RegOption("Show Line", TOptionType.BOOLEAN, this.showLine);
    this.api.RegOption("Mode", TOptionType.STRING, this.mode);

    // Optional: Set parameter constraints
    this.api.SetOptionRange("Period", 1, 200);
    this.api.SetOptionDigits("Period", 0);
}

2. Create and Configure Buffers

Buffers determine visualization and must be properly set up:

// Declare as class-level field
public mainBuffer!: TIndexBuffer;

public Init(): void {
    // 1. Register total number of buffers (MUST be called first)
    this.api.IndicatorBuffers(1);

    // 2. Create the buffer
    this.mainBuffer = this.api.CreateIndexBuffer();

    // 3. Bind buffer to index
    this.api.SetIndexBuffer(0, this.mainBuffer);

    // 4. Configure buffer appearance
    this.api.SetIndexLabel(0, "Main Line");
    this.api.SetIndexStyle(0, TDrawStyle.LINE, TPenStyle.SOLID, 1, '#FF0000');

    // 5. Optional: Set drawing start point
    this.api.SetIndexDrawBegin(0, 10);
}

3. Set Indicator Properties

Name: this.api.IndicatorShortName("Your Indicator Name")
Output Window: this.api.SetOutputWindow(TOutputWindow.CHART_WINDOW) or TOutputWindow.SEPARATE_WINDOW

What CAN Be Done in `Init`

Core Setup Methods

this.api.IndicatorShortName(name) - Set indicator display name
this.api.IndicatorBuffers(count) - Register number of buffers
this.api.CreateIndexBuffer() - Create buffer instances
this.api.SetIndexBuffer(index, buffer) - Bind buffers to indexes
this.api.RegOption(name, type, parameter) - Register parameters

Buffer Configuration Methods

this.api.SetIndexLabel(index, label) - Set buffer legend label
this.api.SetIndexStyle(index, drawStyle, penStyle, width, color) - Set visual style
this.api.SetIndexDrawBegin(index, startBar) - Set drawing start point
this.api.SetIndexVisibility(index, visible) - Control buffer visibility

Parameter Configuration Methods

this.api.SetOptionRange(name, min, max) - Set parameter limits
this.api.SetOptionDigits(name, digits) - Set decimal places
this.api.AddOptionValue(name, value) - Add dropdown options

Recommended Methods

this.api.RecalculateMeAlways() - Improves calculation accuracy but could slow down the performance of the indicator
this.api.SetOutputWindow(window) - Configure chart vs oscillator window

Advanced Configuration Methods

this.api.AddLevel(value) - Add horizontal reference lines
this.api.SetLevelValue(index, value) - Set level values
this.api.SetFixedMinMaxValues(min, max) - Set fixed scale range

What CANNOT Be Done in `Init`

❌ Forbidden Operations

Heavy calculations or complex mathematical operations
Per-bar data processing (use Calculate() instead)
Accessing bar data like this.api.Close(index), this.api.High(index), etc.
Setting buffer values using buffer.setValue(index, value)
Time-based calculations or market data analysis
Loops through historical data

❌ Wrong Approach

public Init(): void {
    // DON'T DO THIS - heavy calculations
    for (let i = 0; i < 1000; i++) {
        let value = this.api.Close(i) * 2; // ❌ Wrong!
        this.mainBuffer.setValue(i, value); // ❌ Wrong!
    }
}

✅ Correct Approach

public Init(): void {
    // ✅ Correct - only setup and configuration
    this.api.IndicatorShortName("My Indicator");
    this.api.IndicatorBuffers(1);
    this.mainBuffer = this.api.CreateIndexBuffer();
    // ... other setup code
}

public Calculate(index: number): void {
    // ✅ Correct - calculations go here
    let value = this.api.Close(index) * 2;
    this.mainBuffer.setValue(index, value);
}

Complete Example

export default class MovingAverage extends IndicatorImplementation {
  // Parameters - declared as class-level fields
  public Period!: TOptValue_number;
  public ShowLine!: TOptValue_bool;

  // Buffers - declared as class-level fields
  public MA!: TIndexBuffer;

  public Init(): void {
    // 1. Create and register parameters
    this.Period = this.api.createTOptValue_number(14);
    this.ShowLine = this.api.createTOptValue_bool(true);

    this.api.RegOption("Period", TOptionType.INTEGER, this.Period);
    this.api.RegOption("Show Line", TOptionType.BOOLEAN, this.ShowLine);
    this.api.SetOptionRange("Period", 1, 9999);

    // 2. Set indicator properties
    this.api.IndicatorShortName("Moving Average");
    this.api.SetOutputWindow(TOutputWindow.CHART_WINDOW);
    this.api.RecalculateMeAlways(); // Recommended

    // 3. Create and configure buffers
    this.api.IndicatorBuffers(1);
    this.MA = this.api.CreateIndexBuffer();
    this.api.SetIndexBuffer(0, this.MA);
    this.api.SetIndexLabel(0, "Moving Average");
    this.api.SetIndexStyle(0, TDrawStyle.LINE, TPenStyle.SOLID, 1, "#FF0000");
  }

  public Calculate(index: number): void {
    // Actual calculations happen here, not in Init()
    const periodValue = this.Period.value; // Access parameter value
    // ... calculation logic
  }
}

Key Rules Summary

Init() is for setup only - no calculations or data processing
All parameters must be created AND registered in Init()
All buffers must be declared, created, and configured in Init()
Use factory methods for parameter creation (createTOptValue_number, etc.)
Register buffer count first with IndicatorBuffers() before configuring buffers
Try including RecalculateMeAlways() for better accuracy
Use Calculate() for all data processing and calculations

Pro Tip

Remember: Init() runs once when the indicator loads. It defines the structure, settings, and appearance. All dynamic calculations and data processing must happen in Calculate() which runs once per bar.

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Last updated 2 months ago