Route Instructions

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In this guide you will learn how to get the text instructions for a computed route.

This example computes a route and then displays the text instructions for navigation along that route.

Route instruction list

Routing

A route must be calculated similar to RoutingOnMap example. See Routing on Map Example.

MainActivity.kt

class MainActivity : AppCompatActivity()
{
    //...

    private val routingService = RoutingService(
        onStarted = {
            progressBar.visibility = View.VISIBLE
        },
        onCompleted = { routes, errorCode, _ ->
            progressBar.visibility = View.GONE
            when (errorCode) {
                GemError.NoError -> {
                    if (routes.size == 0) return@onCompleted

                    // Get the main route from the ones that were found.
                    displayRouteInstructions(routes[0])
                }
                GemError.Cancel -> {
                    // The routing action was cancelled.
                }
                else -> {
                    // There was a problem at computing the routing operation.
                    Toast.makeText(
                        this@MainActivity,
                        "Routing service error: ${GemError.getMessage(errorCode)}",
                        Toast.LENGTH_SHORT
                    ).show()
                }
            }
        }
    )
    //...
}

Displaying route instructions

MainActivity.kt

class MainActivity : AppCompatActivity()
{
    //...
    private fun displayRouteInstructions(route: Route)
    {
        // Get the instructions from the route.
        val instructions = SdkCall.execute { route.instructions } ?: arrayListOf()
        val imageSize = resources.getDimension(R.dimen.turn_image_size).toInt()
        listView.adapter = CustomAdapter(instructions, imageSize, isDarkThemeOn())
        //...
    }
    //...
}

The function displayRouteInstructions(..) passes a list of RouteInstruction to a recyclerview adapter. Inside the onBindViewHolder(..) method of the adapter the key informations are filtered and prepared for display.

MainActivity.kt

    override fun onBindViewHolder(viewHolder: RouteInstructionViewHolder, position: Int)
    {
        val instruction = dataSet[position]
        var text: String
        var status: String
        var description: String
        var turnImage: Bitmap?

        SdkCall.execute {
            if (instruction.hasTurnInfo())
            {
                val aInner = if (isDarkThemeOn) Rgba(255, 255, 255, 255) else Rgba(0, 0, 0, 255)
                val aOuter = if (isDarkThemeOn) Rgba(0, 0, 0, 255) else Rgba(255, 255, 255, 255)
                val iInner = Rgba(128, 128, 128, 255)
                val iOuter = Rgba(128, 128, 128, 255)

                turnImage = GemUtilImages.asBitmap(instruction.turnDetails?.abstractGeometryImage, imageSize, imageSize, aInner, aOuter, iInner, iOuter)

                text = instruction.turnInstruction ?: ""
                if (text.isNotEmpty() && text.last() == '.')
                {
                    text.removeSuffix(".")
                }

                val distance = instruction.traveledTimeDistance?.totalDistance?.toDouble() ?: 0.0

                val distText = GemUtil.getDistText(distance.toInt(), SdkSettings.unitSystem)
                status = distText.first
                description = distText.second
                if (status == "0.00")
                {
                    status = "0"
                }

                postOnMain {
                    viewHolder.turnImage.setImageBitmap(turnImage)
                    viewHolder.text.text = text
                    viewHolder.status.text = status
                    viewHolder.description.text = description
                }
            }
        }
    }