npm package: @nightingale-elements/nightingale-track
Description: Basic track type of the viewer.
Author: Gustavo Salazar
Latest version: 5.6.0

# nightingale-track

[![Published on NPM](https://img.shields.io/npm/v/@nightingale-elements/nightingale-track.svg)](https://www.npmjs.com/package/@nightingale-elements/nightingale-track)

The `nightingale-track` component is used to display protein features. 
These features have `start` and `end` positions (these can be the same if the feature 
only spans one amino-acid), a specific shape (rectangle is the default) and a color. 
Features are passed through the `data` property. 
You can specify shapes and colors at an instance level (through a property) 
or individually in the feature `data` (see `data` below). In order to establish the scale, 
it is necessary to set the `length` property (length of the protein sequence in amino-acids).

As `nightingale-track` implements from `withZoom` and `withHighlight`, it will respond 
to zooming changes, highlight events and emit events when interacting with features 
(helpful if you want to display tooltips).

Loading data can be done directly through the `data` property.

There are two types of display available for `nightingale-track`:

- overlapping will display all the features on one single line. 
This means that if a feature overlaps another one, it will be indistinguishable. 
This layout can be useful to display an overview, or when the data is very dense.
- non-overlapping will calculate the best vertical positions for each feature so that they don't overlap.

## Usage

```html
<nightingale-track
  id="my-track-id"
  length="223"
  height="100"
  display-start="1"
  display-end="50"
  layout="non-overlapping"
></nightingale-track>
```

#### Setting the data through property

```typescript
const track = document.querySelector("#my-track-id");
track.data = myDataObject;
```

<!--
#### Setting data through &lt;data-loader&gt;

```
<nightingale-track length="770">
    <nightingale-feature-adapter id="adapter1">
        <data-loader>
          <source src="https://www.ebi.ac.uk/proteins/api/features/P05067?categories=PTM" />
        </data-loader>
    </nightingale-feature-adapter>
</nightingale-track>
``` -->

## API Reference

### Attributes

#### `color?: string | null (default: "gray")`

Color of all features within the track. This could be overwritten 
if the feature in the data specifies its color.

#### `shape?: string | null (default: "rectangle")`

Shape of all features within the track. This could be overwritten 
if the feature in the data specifies its shape.

#### `layout?: "non-overlapping" | "default" (default: "default")`

The track layout. Non-overlapping uses a bumping algorithm 
to make sure none of the features overlap.

### Properties

#### `data: Array`

Array of items of type `Feature` as shown below:

```typescript
type FeatureLocation = {
  fragments: Array<{
    start: number,
    end: number,
  }>,
};
type Feature = {
  accession: string,
  color?: string,
  fill?: string,
  shape?:
    | "rectangle"
    | "roundRectangle"
    | "bridge"
    | "line"
    | "diamond"
    | "chevron"
    | "catFace"
    | "triangle"
    | "wave"
    | "hexagon"
    | "pentagon"
    | "circle"
    | "arrow"
    | "doubleBar"
    | "discontinuosStart"
    | "discontinuos"
    | "discontinuosEnd"
    | "helix"
    | "strand"
    | "leftEndedTag"
    | "rightEndedTag"
    | "doubleEndedTag"
  tooltipContent?: string,
  type?: string,
  locations?: Array<FeatureLocation>,
  feature?: Feature,
  start?: number,
  end?: number,
  opacity?: number,
};
```

**Note**: `locations` is an alternative to `start`-`stop` attributes, 
that expresses that a feature can appear in several locations, and also supports the idea 
of discontinuous features, by allowing to have `fragments`.

So for example a single continuous feature, that only appears once can be represented in 2 ways. 
The classic `{accession:'X', start:2, end:4}` 
or a more verbose version: `{accession:'X', locations: [{fragments: [{start:2, end:4}]}]}` 
and both should generate a track like this:

```
-XXX------
```

If the same feature appears in 2 places in the sequence, it can be represented using `locations`:

```javascript
{
    accession: 'Y',
    locations: [
        {fragments: [{start:2, end:4}]},
        {fragments: [{start:7, end:9}]}
    ]
}
```

To generate a track like

```
-YYY--YYY-
```

Finally, a feature can also be discontinuous, to represent this in our data we use `fragments`:

```javascript
{
    accession: 'Z',
    locations: [
        {fragments: [{start:2, end:4}, {start:7, end:9}]}
    ]
}
```

This expresses that the same instance of the feature Z is split in 2 fragments, 
from 2 to 4 and from 7 to 9. Which could be represented as

```
-ZZZ==ZZZ-
```

### Other attributes and parameters

This component inherits from `NightingaleElement`.

The component implements the following mixins: `withManager`, `withResizable`, `withMargin`, `withPosition`, `withDimensions`, `withHighlight`