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Raw Expression

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Use a JSON string as an expression.
Android Examples App Available

This example code is part of the Maps SDK for Android Examples App, a working Android project available on GitHub. Android developers are encouraged to run the examples app locally to interact with this example in an emulator and explore other features of the Maps SDK.

See our Run the Maps SDK for Android Examples App tutorial for step-by-step instructions.

RawExpressionActivity.kt
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package com.mapbox.maps.testapp.examples

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import com.mapbox.maps.MapInitOptions
import com.mapbox.maps.MapView
import com.mapbox.maps.Style
import com.mapbox.maps.extension.style.expressions.generated.Expression
import com.mapbox.maps.extension.style.layers.generated.FillLayer
import com.mapbox.maps.extension.style.layers.getLayerAs

/**
 * Example showcasing raw expression support through the Value API.
 * This example manipulates the water fill layer of mapbox-streets to:
 * ```
 *         {
 *           "id": "water",
 *           "type": "fill",
 *           "source": "composite",
 *           "source-layer": "water",
 *           "layout": {},
 *           "paint": {
 *               "fill-color": [
 *                   "interpolate",
 *                   ["linear"],
 *                   ["zoom"],
 *                   0, "hsl(103, 80%, 70%)",
 *                   8.53, "hsl(360, 80%, 70%)",
 *                   22, "hsl(196, 80%, 70%)"
 *               ]
 *           }
 *       }
 * ```
 */
class RawExpressionActivity : AppCompatActivity() {

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val mapView = MapView(this, MapInitOptions(context = this, styleUri = Style.MAPBOX_STREETS))
    setContentView(mapView)
    mapView.mapboxMap.getStyle {
      addExpressionToStyle(it)
    }
  }

  private fun addExpressionToStyle(style: Style) {
    style.getLayerAs<FillLayer>("water")?.fillColor(
      Expression.fromRaw(
        """
        [
          "interpolate",
           ["linear"],
           ["zoom"],
           0, "hsl(103, 80%, 70%)",
           8.53, "hsl(360, 80%, 70%)",
           22, "hsl(196, 80%, 70%)"
         ]  
        """.trimIndent()
      )
    )
  }
}
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