FVG Detector (UDT) [CantoLab] — Indicator by CantoLab — TradingView

It’s open-sourced as a reference for other developers (and non-developers curious about the code) on how to structure indicator logic using User-Defined Types (UDTs).

This is my attempt at a clean, minimal, properly organized version of FVG detection logic

Why UDTs?

UDT – user defined types

Normally, FVG detection is written inline wherever it’s needed:

bullFVG = low[1] > high[3]
bearFVG = high[1] < low[3]

This works fine for a small script, but in larger, more complex indicators — the kind that span thousands of lines and check for patterns across many different bar indexes — repeating this logic everywhere gets messy fast.

With a UDT, the FVG becomes a defined structure (top, bottom, kind, indexes, drawings, etc.), and the detection logic becomes a single function. Instead of rewriting the comparison every time, you just call the function and pass in a bar index — it returns the same result. The same approach is used for plotting: drawing, mitigating, and deleting an FVG are each just method calls on the type.

This cuts what would normally be repeated blocks of logic down to just a few reusable lines, and keeps larger scripts far more organized and readable.

What it actually does

– Detects standard 3-candle bullish and bearish FVGs
– Plots them as boxes, with optional borders, mid-line, and labels
– Tracks each FVG and checks for mitigation every bar
– Mitigated FVGs are removed by default, with an option to keep them visible in a muted “failed” state instead

Settings

– Labels — toggle, size, color
– Bull FVG / Bear FVG — toggle, color, optional border
– Mid Line — toggle, color, style, width
– Show Mitigated FVGs — toggle, color

Notes

– Open source — feel free to study, reuse, or build on this
– This indicator does not provide financial advice. You are responsible for how you build around and execute on this information