# MarkColor
Auto-generated config schema for the current JBrowse release — see the [config guide](https://jbrowse.org/jb2/docs/config_guide) for concepts. Provided by the `marks` plugin. [View source](https://github.com/GMOD/jbrowse-components/blob/main/plugins/marks/src/LinearMarkDisplay/markColorConfigSchema.ts).
## Example usage
```js
{ mark: 'bar', encoding: { y: 'score', color: 'steelblue' } }
```
```js
{
mark: 'point',
encoding: { y: 'score', color: { field: 'strand', domain: ['1', '-1'] } },
}
```
```js
{
mark: 'span',
encoding: {
color: {
field: 'score',
scale: 'log',
domainMin: 1,
domainMax: 1000,
range: ['white', 'red'],
},
},
}
```
```js
{
mark: 'bar',
encoding: {
y: 'score',
color: {
field: 'score',
scale: 'linear',
domainMin: -2,
domainMax: 6,
domainMid: 0,
range: ['blue', 'white', 'red'],
},
},
}
```
```js
{
mark: 'point',
encoding: {
y: 'score',
color: {
field: 'pip',
scale: 'threshold',
domain: [0.1, 0.5],
range: ['#357ebd', '#eea236', '#d43f3a'],
},
},
}
```
_See the **Config slots** section below for all available configuration fields._
A mark's `encoding.color`: one CSS colour or `jexl:` callback for every
instance, or a field through a categorical scale (a `range` colour per
value), a `linear` or `log` scale (a ramp between `domainMin` and
`domainMax`, `domainMid` placing its middle stop where a diverging ramp
turns) or a `threshold` scale (a `range` colour per interval between the
cut points `domain` lists). A string is the constant; the object binds the
field, and a scale is what the legend describes.
## Config slots
These slots go on a display entry: `"displays": [{ "type": "MarkColor", ... }]`, or in the track's [`displayDefaults`](https://jbrowse.org/jb2/docs/config_guides/tracks#configuring-displays) when this is its default display. Slot types (`fileLocation`, `frozen`, ...) are explained in the [config slot types reference](https://jbrowse.org/jb2/docs/config_guides/slot_types). Slots a base configuration contributes are listed here too, so this table is the whole surface.
| Slot | Description |
| --- | --- |
| **value**
[`color`](https://jbrowse.org/jb2/docs/config_guides/slot_types#color) = '#0068d1' | A CSS colour, or a jexl callback over `feature` returning one, for a mark whose colour is not a scale. Writing `color: 'red'` or `color: 'jexl:…'` directly on the encoding lands here.
_callback args:_ `feature` |
| **breaks**
`stringArray` = [] | The values a categorical key lists, in this order; empty lists every value the loaded regions met. A value left out still paints, as ggplot2's `breaks` leaves it. |
| **descending**
[`boolean`](https://jbrowse.org/jb2/docs/config_guides/slot_types#boolean) = false | A threshold key lists its intervals from the highest down, the way a vertical stepped legend stands. |
| **missingLabel**
[`maybeString`](https://jbrowse.org/jb2/docs/config_guides/slot_types#the-maybe-types) | What the key calls a feature with nothing in `field`; unset is "(no value)". |
| **field**
[`featureField`](https://jbrowse.org/jb2/docs/config_guides/slot_types#featurefield) = '' | the feature field a scale reads, or a jexl expression over feature, which is slower per feature and so the opt-in |
| **scale**
[`maybeStringEnum`](https://jbrowse.org/jb2/docs/config_guides/slot_types#the-maybe-types) (none, categorical, linear, log, threshold) | how field becomes a colour: categorical hands out range colours per distinct value; linear and log read the value between domainMin and domainMax into a ramp; threshold cuts the value at the domain and hands each interval a range colour; none paints value, keeping a field for a switch back; unset beside a field, it is categorical |
| **domain**
`stringArray` = [] | for a categorical scale, the values in legend order, walking the range from the first entry and continuing into the default palette past its end (a value left out derives its colour from itself and never takes a listed value's, so every region agrees); for a threshold scale, the cut points in ascending order, a value taking the range entry for the number of them it is at or past, so range has one entry more than this; a linear or log scale reads domainMin and domainMax instead |
| **domainMin**
[`maybeNumber`](https://jbrowse.org/jb2/docs/config_guides/slot_types#the-maybe-types) | the bottom of a linear or log scale's domain; unset follows the loaded values |
| **domainMax**
[`maybeNumber`](https://jbrowse.org/jb2/docs/config_guides/slot_types#the-maybe-types) | the top of a linear or log scale's domain; unset follows the loaded values |
| **domainQuantile**
[`number`](https://jbrowse.org/jb2/docs/config_guides/slot_types#number) = 1 | the quantile an open end of a linear or log scale follows over the loaded values, each sign anchored at 0: 1 their extremes, 0.99 clips the outermost 1%
_advanced_ |
| **range**
[`colorArray`](https://jbrowse.org/jb2/docs/config_guides/slot_types#colorarray) = [] | CSS colours a categorical scale hands its domain in order, a threshold scale its intervals, or a linear or log scale's ramp as evenly spaced stops; empty is the default palette, or the scheme |
| **labels**
`stringArray` = [] | what the key names each domain value, one each in order, or under threshold each interval from the lowest; one past the list keeps its own name |
| **scheme**
[`maybeStringEnum`](https://jbrowse.org/jb2/docs/config_guides/slot_types#the-maybe-types) (viridis, magma, inferno, cividis, juicebox, fall, reds, blues, redblue, purpleorange) | a named ramp for a linear or log scale; range's colours, where it lists any, win over it |
| **reverse**
[`boolean`](https://jbrowse.org/jb2/docs/config_guides/slot_types#boolean) = false | turns a linear or log scale's ramp round, so its last colour paints the bottom of the domain |
| **domainMid**
[`maybeNumber`](https://jbrowse.org/jb2/docs/config_guides/slot_types#the-maybe-types) | the value the ramp's middle stop sits at, so a diverging ramp centres somewhere other than the middle of the domain, both sides on one scale: the farther end of the domain reaches its end colour and equal distances from the middle take equal colours; unset, the stops are evenly spaced across it |
| **title**
[`maybeString`](https://jbrowse.org/jb2/docs/config_guides/slot_types#the-maybe-types) | key title; unset follows field, "" draws none |