# FeatureGateMixin
Auto-generated from the @jbrowse/mobx-state-tree model in the source — see the [developer guide](https://jbrowse.org/jb2/docs/developer_guide/) for concepts. Provided by the `features` plugin. [View source](https://github.com/GMOD/jbrowse-components/blob/main/plugins/features/src/shared/FeatureGateMixin.ts).
The density axis of the region-too-large gate, composed after
`MultiRegionDisplayMixin`. A display opts in by composing this, spreading
`featureGateConfigSchemaFields` into its config, and calling
`commitGateMeasurements` from its fetch's `onComplete`.
## Volatiles
| Member | Description |
| --- | --- |
| **densityStatsPerRegion**
ObservableMap<number, RegionDensityStats> | Per-region feature counts, so the verdict is a live max at the current `bpPerPx`. |
## Getters
| Member | Description |
| --- | --- |
| **gateEnabled**
boolean | `types.compose` resolves a collision to the later argument, so this mixin must follow the one declaring the byte-gate opt-in. |
| **visibleFeatureDensityPerPx**
number | Density at the debounced `coarseBpPerPx`, so the verdict shares the layout cadence. |
| **configuredMaxFeatureScreenDensity**
number | The `maxFeatureScreenDensity` slot. Overridable for a display that holds it under a sub-schema (the variant display's `records`). |
| **maxFeatureDensity**
number | undefined | Undefined when the axis may not act. |
| **densityTooLarge**
boolean | |
## Methods
| Member | Description |
| --- | --- |
| **observedMaxDensity**
(bpPerPx: number) => number | |
## Actions
| Member | Description |
| --- | --- |
| **setDensityStats**
(displayedRegionIndex: number, stats: RegionDensityStats) => void | |
| **clearGateMeasurements**
() => void | `RegionTooLargeMixin`'s hook: the density axis drops its counts on the trigger that drops the byte estimate, so a gate's measurements always come from one file. |
| **commitGateMeasurements**
(measurements: RegionGateMeasurement[], issued: GateFetchState) => void | Judged by the tier captured at issue. |