CreateIndexBuffer

Creates a new buffer for storing indicator values.

Important: This method should only be used inside the Init() method during indicator initialization.

Syntax

CreateIndexBuffer(): TIndexBuffer

Parameters

This method does not take any parameters.

Return Value

Returns a TIndexBuffer object that can be used to store indicator values.

Description

The CreateIndexBuffer method creates a new buffer for storing indicator values. Buffers are essential for displaying data on charts and must be properly declared, created, and configured during indicator setup.

Buffer Management Rules:

• Declare all buffers as class-level fields using the ! syntax

• Create buffers in Init() using CreateIndexBuffer()

• Register buffer count with IndicatorBuffers()

• Assign buffers to indexes with SetIndexBuffer()

• Configure buffer appearance with SetIndexStyle()

See TIndexBuffer for more information about working with indicator buffers.

Proper Buffer Declaration

All buffers must be declared as class-level fields with the non-null assertion operator (!):

// ✅ Correct - declare as class-level fields
export default class MyIndicator extends IndicatorImplementation {
  public mainBuffer!: TIndexBuffer;
  public signalBuffer!: TIndexBuffer;
  public helperBuffer!: TIndexBuffer;

  public Init(): void {
    this.mainBuffer = this.api.CreateIndexBuffer();
    this.signalBuffer = this.api.CreateIndexBuffer();
    this.helperBuffer = this.api.CreateIndexBuffer();
  }
}
// ❌ Wrong - don't use api methods (any api methods, including CreateIndexBuffer) in class level fields
export default class MyIndicator extends IndicatorImplementation {
  public mainBuffer = this.api.CreateIndexBuffer();
  public signalBuffer = this.api.CreateIndexBuffer();
  public helperBuffer = this.api.CreateIndexBuffer();

  public Init(): void {}
}

Complete Buffer Setup Workflow

Step 1: Declare Buffers (Class Level)

export default class MovingAverageIndicator extends IndicatorImplementation {
    // Declare all buffers as class properties
    public maBuffer!: TIndexBuffer;
    public signalBuffer!: TIndexBuffer;

Step 2: Create and Configure in Init()

    public Init(): void {
        // 1. Register total number of buffers FIRST
        this.api.IndicatorBuffers(2);

        // 2. Create buffer instances
        this.maBuffer = this.api.CreateIndexBuffer();
        this.signalBuffer = this.api.CreateIndexBuffer();

        // 3. Assign buffers to indexes
        this.api.SetIndexBuffer(0, this.maBuffer);
        this.api.SetIndexBuffer(1, this.signalBuffer);

        // 4. Configure buffer appearance
        this.api.SetIndexStyle(0, TDrawStyle.LINE, TPenStyle.SOLID, 2, "#0000ff");
        this.api.SetIndexStyle(1, TDrawStyle.LINE, TPenStyle.DASH, 1, "#ff0000");

        // 5. Set buffer labels
        this.api.SetIndexLabel(0, "Moving Average");
        this.api.SetIndexLabel(1, "Signal Line");
    }

Step 3: Use Buffers in Calculate()

    public Calculate(index: number): void {
        // Use buffers to store and retrieve values
        const closePrice = this.api.Close(index);
        const maValue = this.calculateMA(index);

        // Set buffer values
        this.maBuffer.setValue(index, maValue);
        this.signalBuffer.setValue(index, maValue * 1.1);

        // Get buffer values (from previous bars)
        const previousMA = this.maBuffer.getValue(index + 1);
    }
}

Buffer Creation Rules

✅ Must Be Done in Init()

• Create all buffers with CreateIndexBuffer()

• Register buffer count with IndicatorBuffers()

• Assign buffers to indexes with SetIndexBuffer()

• Configure initial styles with SetIndexStyle()

❌ Cannot Be Done Outside Init()

• Creating new buffers in Calculate() or other methods

• Changing buffer count after initialization

• Reassigning buffer indexes during runtime

Complete Example

export default class AdvancedIndicator extends IndicatorImplementation {
  // 1. Declare all buffers as class-level fields
  public fastMA!: TIndexBuffer;
  public slowMA!: TIndexBuffer;
  public signalBuffer!: TIndexBuffer;
  public helperBuffer!: TIndexBuffer;

  public Init(): void {
    // 2. Register total buffer count
    this.api.IndicatorBuffers(4);

    // 3. Create buffer instances
    this.fastMA = this.api.CreateIndexBuffer();
    this.slowMA = this.api.CreateIndexBuffer();
    this.signalBuffer = this.api.CreateIndexBuffer();
    this.helperBuffer = this.api.CreateIndexBuffer();

    // 4. Assign to indexes
    this.api.SetIndexBuffer(0, this.fastMA);
    this.api.SetIndexBuffer(1, this.slowMA);
    this.api.SetIndexBuffer(2, this.signalBuffer);
    this.api.SetIndexBuffer(3, this.helperBuffer);

    // 5. Configure styles
    this.api.SetIndexStyle(0, TDrawStyle.LINE, TPenStyle.SOLID, 1, "#0000ff");
    this.api.SetIndexStyle(1, TDrawStyle.LINE, TPenStyle.SOLID, 1, "#ff0000");
    this.api.SetIndexStyle(
      2,
      TDrawStyle.HISTOGRAM,
      TPenStyle.SOLID,
      2,
      "#00ff00"
    );
    this.api.SetIndexStyle(3, TDrawStyle.NONE, TPenStyle.SOLID, 1, "#000000"); // Hidden

    // 6. Set labels
    this.api.SetIndexLabel(0, "Fast MA");
    this.api.SetIndexLabel(1, "Slow MA");
    this.api.SetIndexLabel(2, "Signal");
  }

  public Calculate(index: number): void {
    // Use buffers for calculations and display
    const fastValue = this.calculateFastMA(index);
    const slowValue = this.calculateSlowMA(index);

    this.fastMA.setValue(index, fastValue);
    this.slowMA.setValue(index, slowValue);
    this.helperBuffer.setValue(index, fastValue - slowValue);

    // Conditional signal display
    if (Math.abs(fastValue - slowValue) > 0.01) {
      this.signalBuffer.setValue(index, fastValue);
    }
  }
}

Key Rules Summary

1. Declare buffers as class-level fields with ! syntax

2. Create buffers only in Init() using CreateIndexBuffer()

3. Assign buffers to indexes with SetIndexBuffer()

4. Configure appearance with SetIndexStyle()

5. Use buffers in Calculate() for data storage and retrieval

6. Never create buffers outside Init() - this will cause errors