The DrawOnLastBarOnly instruction in ProBuilder language is used to limit the display of graphical objects to only the last bar on a chart. This is particularly useful for focusing visual indicators or elements on the most recent data point, which is often the most relevant in real-time trading analysis.

Syntax:

DefParam DrawOnLastBarOnly = true

This instruction should be declared at the beginning of your script using the DefParam keyword. It ensures that any graphical object or indicator that follows in the code will only be drawn on the last bar of the chart.

Example:

DefParam DrawOnLastBarOnly = true
once DrawText("LastBar", barindex, close, "Arial", 12, colorRed)

In this example, the text “LastBar” will only appear on the last bar of the chart, aligned with the closing price of that bar. The text is styled in Arial font, size 12, and colored red.

Additional Information:

• This instruction is often used in conjunction with CalculateOnLastBars to optimize the calculation and rendering of indicators or objects only for a specified number of the most recent bars, further enhancing performance.
• Setting DrawOnLastBarOnly to true is particularly useful in dynamic charts where the focus is on the latest data, and historical graphical elements are unnecessary or could clutter the view.

Understanding and using the DrawOnLastBarOnly instruction can significantly improve the clarity and performance of your trading scripts by focusing resources and attention on the most current market data.