2Gis Full SDK for Compose/ru.dgis.sdk.compose.navigation.controls.defaultcontrols.map/DefaultMapControlsViewModel

DefaultMapControlsViewModel

class DefaultMapControlsViewModel(val map: Map, navigationManager: NavigationManager) : MapControlsViewModel

Default implementation of MapControlsViewModel.

This ViewModel manages the visibility of map controls based on available space and navigation state. For proper operation, the free roam state must be set via setIsFreeRoam method, which affects the visibility of certain controls like the add road event button.

Measurement mechanism

Controls visibility is calculated based on their measured heights and available space. The measurement flow works as follows:

All visibility states are initialized to true so controls can render and be measured
Composable reports each control's height via set*Height() methods
Once all heights are known, updateMapControlsVisibilityInternal calculates which controls fit
Controls that don't fit are hidden (visibility = false)

Composable-side requirements

The Composable must report height ONLY when the control is visible. Otherwise, a measurement loop occurs:

Control visible -> height = 255 -> ViewModel hides control
Control hidden -> height = 10 (empty) -> ViewModel shows control
Repeat infinitely (UI flickers)

Correct implementation in MapControl:

.onSizeChanged {
    if (visibility) {  // Only measure when visible
        onHeightChanged(it.height)
    }
}

Constructors

DefaultMapControlsViewModel

constructor(map: Map, navigationManager: NavigationManager)

Properties

addRoadEventButtonVisibility

open override val addRoadEventButtonVisibility: StateFlow<Boolean>

Observable state indicating whether the add road event button should be visible. Shown when all conditions are met:

compassVisibility

open override val compassVisibility: StateFlow<Boolean>

Observable state indicating whether the compass control should be visible. Visibility depends on available vertical space.

followHideable

open override val followHideable: StateFlow<Boolean>

Observable state indicating whether the follow button can be hidden. True for non-pedestrian routes, false for pedestrian routes.

followVisibility

open override val followVisibility: StateFlow<Boolean>

Observable state indicating whether the my location (follow) button should be visible. This control has the highest priority and is shown when any space is available.

map

open override val map: Map

The map instance used for map controls.

mapControlsUnusedHeight

open override val mapControlsUnusedHeight: StateFlow<Int?>

Observable state of the remaining vertical space after all visible controls are placed. Null if controls haven't been measured yet, otherwise the unused height in pixels.

trafficAndParkingVisibility

open override val trafficAndParkingVisibility: StateFlow<Boolean>

Observable state indicating whether the traffic and parking button should be visible. Visibility depends on available space and whether the route is pedestrian.

zoomVisibility

open override val zoomVisibility: StateFlow<Boolean>

Observable state indicating whether the zoom controls should be visible. Visibility depends on available vertical space.

Functions

onCleared

open override fun onCleared()

Cleans up resources and closes all connections. Must be called when the ViewModel is no longer needed to prevent memory leaks.

setAddRoadEventButtonHeight

open override fun setAddRoadEventButtonHeight(height: Int)

Sets the measured height of the add road event button. Used for calculating visibility based on available space.

setCompassHeight

open override fun setCompassHeight(height: Int)

Sets the measured height of the compass control. Used for calculating visibility based on available space.

setFollowHeight

open override fun setFollowHeight(height: Int)

Sets the measured height of the my location (follow) button. Used for calculating visibility based on available space.

setIsFreeRoam

open override fun setIsFreeRoam(value: Boolean)

Updates the free roam state which affects the visibility of certain controls. In free roam mode, the add road event button may be shown if space permits.

setMapControlsAreaHeight

open override fun setMapControlsAreaHeight(height: Int)

Sets the total available height for map controls area. This triggers recalculation of which controls can fit in the available space.

setTrafficAndParkingHeight

open override fun setTrafficAndParkingHeight(height: Int)

Sets the measured height of the traffic and parking control. Used for calculating visibility based on available space.

setZoomHeight

open override fun setZoomHeight(height: Int)

Sets the measured height of the zoom controls. Used for calculating visibility based on available space.