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add viewpointChangedLambda #159

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Merged
merged 2 commits into from
Oct 24, 2023
Merged

add viewpointChangedLambda #159

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9e36e0c
add viewpointChangedLambda
puneet-pdx Oct 20, 2023
ead6fc1
address code review feedback
puneet-pdx Oct 23, 2023
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14 changes: 14 additions & 0 deletions toolkit/geo-compose/src/main/java/com/arcgismaps/toolkit/geocompose/Map.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ package com.arcgismaps.toolkit.geocompose
import androidx.compose.foundation.layout.Box
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.LocalContext
Expand All @@ -30,19 +31,22 @@ import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.viewinterop.AndroidView
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.view.MapView
import kotlinx.coroutines.launch

/**
* A compose equivalent of the [MapView].
*
* @param modifier Modifier to be applied to the Map
* @param arcGISMap the [ArcGISMap] to be rendered by this composable
* @param onViewPointChanged lambda invoked when the viewpoint of the Map has changed
* @param overlay the composable overlays to display on top of the Map. Example, a compass, floorfilter etc.
* @since 200.3.0
*/
@Composable
public fun Map(
modifier: Modifier = Modifier,
arcGISMap: ArcGISMap? = null,
onViewPointChanged: (() -> Unit)? = null,
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Not sure if there is a reason this is initialized to be null, but you could initialize it to a default lambda.

Suggested change
onViewPointChanged: (() -> Unit)? = null,
onViewPointChanged: () -> Unit = {},

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Defaulting the parameter to null is the correct thing to do. It expresses to the user that the parameter is "absent". See Compose API guidelines.

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casing: It''s a "Viewpoint" that is changing, not a "ViewPoint", so the parameter name should be onViewpointChanged .

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We need to consider passing the changed viewpoint to the event callback, so users can immediately process the changed viewpoint. Since there are two types of viewpoints the user might be interested in, we might have to support two different "viewpoint changed events", one passing a viewpoint of type CenterAndScale and another passing a viewpoint of type BoundingGeometry. We need to think about the naming, but something like this may work:

onViewPointChangedForScale: ((Viewpoint) -> Unit)? = null,
onViewPointChangedForVisibleArea: ((Viewpoint) -> Unit)? = null,

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As per our discussion, I have updated the parameter name

overlay: @Composable () -> Unit = {}
) {
val lifecycleOwner = LocalLifecycleOwner.current
Expand All @@ -69,6 +73,16 @@ public fun Map(
mapView.onDestroy(lifecycleOwner)
}
}

LaunchedEffect(Unit) {
onViewPointChanged?.let { onViewPointChangedLambda ->
launch {
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LaunchedEffect should create a coroutine scope, so a launch is not needed here

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I have updated it as per @gunt0001 's comment.

mapView.viewpointChanged.collect {
onViewPointChangedLambda()
}
}
}
}
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We should always collect the viewpoint changes on the MapView, regardless of whether a callback parameter was passed or not. We also need to prevent the LaunchedEffect from recomposing when the parameter changes. You can achieve this with rememberUpdatedState.

In principle the implementation would look like this:

val currentViewPointChanged = rememberUpdatedState(onViewPointChanged)
LaunchedEffect(Unit) {
   launch {
      mapView.viewpointChanged.collect {
         currentViewPointChanged?.let {
            it()
         }
      }
   }
}

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updated

}

@Preview
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