StyleSheet

StyleSheet

Style functions

Zoom based expressions

This is a value function defining a style value that changes as the zoom level changes. The layout and paint attribute properties of the layer can be set to style function objects. Use a camera function to create the illusion of depth and control data density.

// color would change based on zoom level keys.
[
  'interpolate',
  ['exponential', 1.5],
  ['zoom'],
  0, 'blue',
  10, 'green',
  20, 'yellow'
];

// Example of use inside stylesheet
{
  fillColor: [
    'step',
    ['zoom'],
    'blue',
    20, 'green'
  ]
}

Attribute based expressions

This is a value function defining a style value that changes with its properties. The layout and paint attribute properties of the layer can be set to style function objects. Use source functions to visually differentate types of features within the same layer or create data visualizations.

// would color the layer based the property rating=[1, 5]
[
  'step',
  ['get', 'rating'],
  'red',
  2, 'orange',
  3, 'yellow',
  4, 'yellowgreen',
  5, 'green',
];

// Example of use inside stylesheet
{
  circleColor: [
    'step',
    ['get', 'rating'],
    'red',
    2, 'orange',
    3, 'yellow',
    4, 'yellowgreen',
    5, 'green',
  ],
}

Nested expressions

This is a value function defining a style value that changes with the feature attributes at each map zoom level. The layout and paint attribute properties of the layer can be set to style function objects. Use composite functions to allow the appearance of a map feature to change with both its attributes and the map zoom level. Note that support for composite functions is not yet complete in the Android/iOS SDK's.

// would change based on the zoom level and rating value
// {zoom_level}: [{value}, {style_value}]
[
  'step',
  ['zoom'],
  [
    'step',
    ['get','rating'],
    0,
    5, 5
  ],
  20, [
    'step',
    ['get','rating'],
    0,
    5, 20
  ]
]

{
  circleRadius: [
    'step',
    ['zoom'],
    [ 'step',
      ['get','rating'],
      0,
      5, 5
    ],
    20, [ 'step',
          ['get','rating'],
          0,
          5, 20
        ],
]
};

Simple expressions

['get', attributeName] - replaces identity(attributeName)

This is just a source style function under the hood. For example say if you had a feature property with an attribute height. Identity means that it will just equal the attribute value, so there is no need to provide any stops

{
  fillExtrusionHeight: ['get', 'height'],
}

StyleSheet Examples

const styles = {
  buildings: {
    fillColor: 'blue',
  },
  street: {
    lineColor: 'green',
  }
};

...

<Vietmap.FillLayer ... style={styles.buildings} />
<Vietmap.FillLayer ... style={styles.street} />

const layerStyles = {
  singlePoint: {
    circleColor: 'green',
    circleOpacity: 0.84,
    circleStrokeWidth: 2,
    circleStrokeColor: 'white',
    circleRadius: 5,
  },

  clusteredPoints: {
    circleColor: [
      'interpolate',
      ['exponential', 1.5],
      ['get','point_count'],
      25, 'yellow',
      50, 'red',
      75, 'blue',
      100, 'orange',
      300, 'pink',
      750, 'white',
    ],

    circleRadius: [
      'interpolate',
      ['exponential', 1.5],
      ['get','point_count'],
      [0, 15],
      [100, 20],
      [750, 30],
    ],

    circleOpacity: 0.84,
    circleStrokeWidth: 2,
    circleStrokeColor: 'white',
  },

  clusterCount: {
    textField: ['get', 'point_count'],
    textSize: 12,
  },
});

...

<Vietmap.SymbolLayer
  id='pointCount'
  style={layerStyles.clusterCount} />

<Vietmap.CircleLayer
  id='clusteredPoints'
  belowLayerID='pointCount'
  filter={['has', 'point_count']}
  style={layerStyles.clusteredPoints} />

<Vietmap.CircleLayer
  id='singlePoint'
  filter={['!has', 'point_count']}
  style={layerStyles.singlePoint} />

const layerStyles = Vietmap.StyleSheet.create({
    building: {
      fillExtrusionOpacity: 1,
      fillExtrusionHeight: ['get', 'height'],
      fillExtrusionBase: ['get', 'min_height'],
      fillExtrusionColor: [
        'interpolate',
        ['exponential', 1.5],
        ['get', 'height'],
        [0, 'white'],
        [50, 'blue'],
        [100, 'red'],
      ],
    },
    fillExtrusionColorTransition: { duration: 2000, delay: 0 },
  },
  streets
:
{
  lineColor: 'blue',
    lineWidth
:
  2,
    lineOpacity
:
  0.50,
    lineJoin
:
  Vietmap.LineJoin.Round,
    lineCap
:
  Vietmap.LineCap.Round,
    lineDasharray
:
  [2, 2],
}
,
})
;

...

<Vietmap.FillExtrusionLayer
  id='building3d'
  sourceLayerID='building'
  style={layerStyles.building}/>

<Vietmap.LineLayer
  id='streetLineColor'
  sourceLayerID='road'
  minZoomLevel={14}
  belowLayerID='building3d'
  style={layerStyles.streets}/>