kscience/maps-kt
8
0
Fork 0
Code Issues Pull Requests 3 Packages Projects Releases 1 Wiki Activity

Partial fix for TAVRIDA-T-3

Browse Source 
(Zoom in works corretly, zoom out - not)
This commit is contained in:
Alexander Nozik 2022-07-12 22:10:48 +03:00
parent 2ac4bdfd4f
commit 960c64d480
No known key found for this signature in database
GPG Key ID: F7FCF2DD25C71357
2 changed files with 17 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
src/commonMain/kotlin/centre/sciprog/maps/MapViewPoint.kt
View File

@ -1,6 +1,8 @@
package centre.sciprog.maps
import kotlin.math.pow
import kotlin.math.roundToInt
import kotlin.math.sign
/**
* Observable position on the map. Includes observation coordinate and [zoom] factor
@ -35,3 +37,12 @@ fun MapViewPoint.move(delta: GeodeticMapCoordinates): MapViewPoint {
}
fun MapViewPoint.zoom(zoomDelta: Double): MapViewPoint = copy(zoom = (zoom + zoomDelta).coerceIn(2.0, 18.0))
fun MapViewPoint.zoom(zoomDelta: Double, at: GeodeticMapCoordinates): MapViewPoint {
val difScale = 2.0.pow(-zoomDelta)
val newCenter = GeodeticMapCoordinates.ofRadians(
focus.latitude + (at.latitude - focus.latitude) * difScale,
focus.longitude + (at.longitude - focus.longitude) * difScale
)
return MapViewPoint(newCenter, (zoom + zoomDelta).coerceIn(2.0, 18.0))
}

6
src/jvmMain/kotlin/centre/sciprog/maps/compose/MapViewJvm.kt
View File

@ -70,7 +70,11 @@ actual fun MapView(
val (xPos, yPos) = it.changes.first().position
onClick(DpOffset(xPos.toDp(), yPos.toDp()).toGeodetic())
}.onPointerEvent(PointerEventType.Scroll) {
viewPoint = viewPoint.zoom(-it.changes.first().scrollDelta.y.toDouble())
val change = it.changes.first()
val (xPos, yPos) = change.position
//compute invariant point of translation
val at = DpOffset(xPos.toDp(), yPos.toDp()).toGeodetic()
viewPoint = viewPoint.zoom(-change.scrollDelta.y.toDouble(), at)
}.pointerInput(Unit) {
detectDragGestures { _: PointerInputChange, dragAmount: Offset ->
viewPoint = viewPoint.move(-dragAmount.x, +dragAmount.y)