kscience/maps-kt
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Pan logic on coroutines

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This commit is contained in:
Alexander Nozik 2022-07-13 21:24:46 +03:00
parent a1151ebb62
commit 6f6c4b117b
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2 changed files with 8 additions and 5 deletions
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7
src/commonMain/kotlin/centre/sciprog/maps/MapViewPoint.kt
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@ -10,10 +10,13 @@ data class MapViewPoint(
val focus: GeodeticMapCoordinates, val focus: GeodeticMapCoordinates,
val zoom: Double, val zoom: Double,
) { ) {
val scaleFactor by lazy { WebMercatorProjection.scaleFactor(zoom.roundToInt()) } val scaleFactor by lazy { WebMercatorProjection.scaleFactor(zoom) }
} }
fun MapViewPoint.move(deltaX: Double, deltaY: Double): MapViewPoint { /**
*
*/
internal fun MapViewPoint.move(deltaX: Double, deltaY: Double): MapViewPoint {
val newCoordinates = GeodeticMapCoordinates.ofRadians( val newCoordinates = GeodeticMapCoordinates.ofRadians(
(focus.latitude + deltaY / scaleFactor).coerceIn( (focus.latitude + deltaY / scaleFactor).coerceIn(
-MercatorProjection.MAXIMUM_LATITUDE, -MercatorProjection.MAXIMUM_LATITUDE,

6
src/commonMain/kotlin/centre/sciprog/maps/WebMercatorProjection.kt
View File

@ -14,10 +14,10 @@ public object WebMercatorProjection {
/** /**
* Compute radians to projection coordinates ratio for given [zoom] factor * Compute radians to projection coordinates ratio for given [zoom] factor
*/ */
public fun scaleFactor(zoom: Int) = 256.0 / 2 / PI * 2.0.pow(zoom) public fun scaleFactor(zoom: Double) = 256.0 / 2 / PI * 2.0.pow(zoom)
public fun toGeodetic(mercator: WebMercatorCoordinates): GeodeticMapCoordinates { public fun toGeodetic(mercator: WebMercatorCoordinates): GeodeticMapCoordinates {
val scaleFactor = scaleFactor(mercator.zoom) val scaleFactor = scaleFactor(mercator.zoom.toDouble())
val longitude = mercator.x / scaleFactor - PI val longitude = mercator.x / scaleFactor - PI
val latitude = (atan(exp(PI - mercator.y / scaleFactor)) - PI / 4) * 2 val latitude = (atan(exp(PI - mercator.y / scaleFactor)) - PI / 4) * 2
return GeodeticMapCoordinates.ofRadians(latitude, longitude) return GeodeticMapCoordinates.ofRadians(latitude, longitude)
@ -29,7 +29,7 @@ public object WebMercatorProjection {
public fun toMercator(gmc: GeodeticMapCoordinates, zoom: Int): WebMercatorCoordinates { public fun toMercator(gmc: GeodeticMapCoordinates, zoom: Int): WebMercatorCoordinates {
require(abs(gmc.latitude) <= MercatorProjection.MAXIMUM_LATITUDE) { "Latitude exceeds the maximum latitude for mercator coordinates" } require(abs(gmc.latitude) <= MercatorProjection.MAXIMUM_LATITUDE) { "Latitude exceeds the maximum latitude for mercator coordinates" }
val scaleFactor = scaleFactor(zoom) val scaleFactor = scaleFactor(zoom.toDouble())
return WebMercatorCoordinates( return WebMercatorCoordinates(
zoom = zoom, zoom = zoom,
x = scaleFactor * (gmc.longitude + PI), x = scaleFactor * (gmc.longitude + PI),