tmp-react-map-gl-draw/README.md

A lite version editing layer with react

# React Map GL Draw

`react-map-gl-draw` is a react based drawing library tailored for [`react-map-gl`](https://github.com/uber/react-map-gl).

## Options 
- `mode` (String, Optional)
  - `EditorModes.READ_ONLY` - Not interactive. This is the default mode.
  - `EditorModes.SELECT` - Lets you select, delete, and drag features.
  - `EditorModes.EDITTING` - Lets you select, delete, and drag vertices; and drag features.
  - `EditorModes.DRAW_PATH` - Lets you draw a GeoJson `LineString` feature.
  - `EditorModes.DRAW_POLYGON` - Lets you draw a GeoJson `Polygon` feature.
  - `EditorModes.DRAW_POINT` - Lets you draw a GeoJson `Point` feature.
  - `EditorModes.DRAW_RECTANGLE` - Lets you draw a `Rectangle` (represented as GeoJson `Polygon` feature).

- `features` (Feature[], Optional) - List of features in GeoJson format. If `features` are provided from users, then `react-map-gl-draw` respect the users' input, and therefore ignore any internal `features`. But if `features` are not provided, then `react-map-gl-draw` manages `features` internally, and users can access and manipulate the features by calling `getFeatures`, `addFeatures`, and `deleteFeatures`.
- `selectedFeatureIndex` (String, Optional) - Index of the selected feature.
- `clickRadius` (Number, Optional) - Radius to detect features around a hovered or clicked point. Default value is `0`

- `onSelect` (Function, Optional) - callback when clicking a position under `SELECT` and `EDITTING` mode. Receives an object containing the following parameters
  - `selectedFeature`: selected feature. `null` if clicked an empty space.
  - `selectedFeatureIndex`: selected feature index.`null` if clicked an empty space.
  - `editHandleIndex`: selected editHandle index. `null` if clicked an empty space.
  - `screenCoords`: screen coordinates of the clicked position.
  - `mapCoords`: map coordinates of the clicked position.
  
- `onUpdate` (Function, Optional) - callback when anything is updated. Receives an object containing the following parameters
  - `features` (Feature[]) - the updated list of GeoJSON features.
  - `editType` (String) -  `addFeature`, `addPosition`, `finishMovePosition`
  - `editContext` (Array) - list of edit objects, depend on `editType`, each object may contain `featureIndexes`, `editHandleIndexes`, `screenCoords`, `mapCoords`.
 
**Feature object structure:**
```js
{
  id, // an unique identified generated inside react-map-gl-draw library 
  geometry: {
    coordinates, // latitude longitude pairs of the geometry points
    type // geojson type, one of `Point`, `LineString`, or `Polygon`
  },
  properties: {
    renderType, // Mainly used for styling, one of `Point`, `LineString`, `Polygon`, or `Rectangle`. Different from `geometry.type`. i.e. a rectangle's renderType is `Rectangle`, and `geometry.type` is `Polygon`. An incomplete (not closed) Polygon's renderType is `Polygon`, `geometry.type` is `LineString`
    ...otherProps // other properties user passed in
  }
}
```

### Styling related options
- `featureStyle` (Object|Function, Optional) : Object - Either a [style objects](https://reactjs.org/docs/dom-elements.html#style) or a function to style a feature, function parameters are 
  - `feature`: feature to style.
  - `index`: index of the feature.
  - `state`: one of `SELECTED`, `HOVERED`, `INACTIVE`, `UNCOMMITTED`, `CLOSING`.
  
Returns is a map of [style objects](https://reactjs.org/docs/dom-elements.html#style) passed to SVG `path` elements.

- `featureShape` (String|Function, Optional): if is a string, should be one of `rect` or `circle`. If is a function, will receive the following parameters
  - `feature`: feature to style.
  - `index`: index of the feature.
  - `state`: one of `SELECTED`, `HOVERED`, `INACTIVE`, `UNCOMMITTED`, `CLOSING`.

- `editHandleStyle` (Object|Function, Optional) : Object - Either a [style objects](https://reactjs.org/docs/dom-elements.html#style) or a function to style an `editHandle, function parameters are 
  - `feature`: feature to style.
  - `index`: index of the editHandle vertex in the feature.
  - `state`: one of `SELECTED`, `HOVERED`, `INACTIVE`, `UNCOMMITTED`, `CLOSING`.
  - `shape`: shape resolved from `editHandleShape`.
  
Returns is a map of [style objects](https://reactjs.org/docs/dom-elements.html#style) passed to SVG `circle` or `rect` elements.

- `editHandleShape` (String|Function, Optional): if is a string, should be one of `rect` or `circle`. If is a function, will receive the following parameters
  - `feature`: feature to style.
  - `index`: index of the editHandle vertex in the feature.
  - `state`: one of `SELECTED`, `HOVERED`, `INACTIVE`, `UNCOMMITTED`, `CLOSING`.

## Explanations
- `Feature`: any drawn shape, one of point, line, polygon or rectangle.
- `EditHandle`: vertex of the feature being edited.

### State related concepts:
- `INACTIVE`: neither selected nor hovered, default state of a complete `feature` or `editHandle`.
- `SELECTED`: being clicked or dragged. 
- `HOVERED`: hovered over by the mouse pointer.
- `UNCOMMITTED`: in the middle of drawing, not yet added to the feature being edited.
- `CLOSING`: closing a polygon. 

### Styling based on `state`:

![img](https://raw.githubusercontent.com/uber-common/deck.gl-data/master/nebula.gl/react-map-gl-draw.png)

As shown in the above image, for the feature currently being edited, 
- `featureStyle({feature, state: SELECTED})` will be applied to the committed parts of the feature. (Green strokes)
- `editHandleStyle({state: SELECTED})` will be applied to the committed editHandle vertices.  (Vertices with black stroke)
- `featureStyle({feature, state: UNCOMMITTED})` will be applied to the uncommitted parts of the feature. (Gray stroke) 
- `editHandleStyle({state: UNCOMMITTED})` will be applied to the uncommitted editHandle vertex. (Gray vertex)

## Methods

##### `getFeatures` 

- Return a list of finished GeoJson features.

##### `addFeatures` (Feature | Feature[])

- Add a single or multiple GeoJson features to editor.

##### `deleteDeatures` (Feature | Feature[])

- Delete a single or multiple GeoJson features to editor.

## Code Example
```js
import React, { Component } from 'react';
import MapGL from 'react-map-gl';
import { Editor, EditorModes } from 'react-map-gl-draw';

const MODES = [
  { id: EditorModes.EDITING, text: 'Select and Edit Feature'},
  { id: EditorModes.DRAW_POINT, text: 'Draw Point'},
  { id: EditorModes.DRAW_PATH, text: 'Draw Polyline'},
  { id: EditorModes.DRAW_POLYGON, text: 'Draw Polygon'},
  { id: EditorModes.DRAW_RECTANGLE, text: 'Draw Rectangle'}
];

const DEFAULT_VIEWPORT = {
  width: 800,
  height: 600,
  longitude: -122.45,
  latitude: 37.78,
  zoom: 14
};

class App extends Component {
  state = {
    // map
    viewport: DEFAULT_VIEWPORT,
    // editor
    selectedMode: EditorModes.READ_ONLY
  };

  _switchMode = evt => {
    const selectedMode = evt.target.id;
    this.setState({
     selectedMode: selectedMode === this.state.selectedMode ? null : selectedMode
    });
  };

  _renderToolbar = () => {
    return (
      <div style={{position: absolute, top: 0, right: 0, maxWidth: '320px'}}>
        <select onChange={this._switchMode}>
          <option value="">--Please choose a mode--</option>
          {MODES.map(mode => <option value={mode.id}>{mode.text}</option>)}
        </select>
      </div>
    );
  };

  render() {
    const { viewport, selectedMode } = this.state;
    return (
      <MapGL
        {...viewport}
        width="100%"
        height="100%"
        mapStyle={'mapbox://styles/mapbox/light-v9'}
        onViewportChange={this.setState({ viewport })}
      >
        <Editor
          clickRadius={12}
          mode={selectedMode}
        />
        {this._renderToolbar()}
      </MapGL>
    );
  }
}
```