Merge pull request #11 from mipt-npm/drag

Ability to customise onDrag functionality

demo/maps/src/jvmMain/kotlin/AngleConversion.kt

@@ -0,0 +1,4 @@
+import kotlin.math.PI
+
+fun Double.toDegrees() = this * 180 / PI
+

demo/maps/src/jvmMain/kotlin/Main.kt

@@ -49,17 +49,26 @@ fun App() {
         var centerCoordinates by remember { mutableStateOf<GeodeticMapCoordinates?>(null) }
 
 
+        val pointOne = 55.568548 to 37.568604
+        var pointTwo by remember { mutableStateOf(55.929444 to 37.518434) }
+        val pointThree = 60.929444 to 37.518434
         MapView(
             mapTileProvider = mapTileProvider,
             initialViewPoint = viewPoint,
             config = MapViewConfig(
                 inferViewBoxFromFeatures = true,
-                onViewChange = { centerCoordinates = focus }
+                onViewChange = { centerCoordinates = focus },
+                onDrag = { start, end ->
+                    if (start.focus.latitude.toDegrees() in (pointTwo.first - 0.05)..(pointTwo.first + 0.05) &&
+                        start.focus.longitude.toDegrees() in (pointTwo.second - 0.05)..(pointTwo.second + 0.05)
+                    ) {
+                        pointTwo = pointTwo.first + (end.focus.latitude - start.focus.latitude).toDegrees() to
+                                pointTwo.second + (end.focus.longitude - start.focus.longitude).toDegrees()
+                        false// returning false, because when we are dragging circle we don't want to drag map
+                    } else true
+                }
             )
         ) {
-            val pointOne = 55.568548 to 37.568604
-            val pointTwo = 55.929444 to 37.518434
-            val pointThree = 60.929444 to 37.518434
 
             image(pointOne, Icons.Filled.Home)
 
@@ -87,7 +96,7 @@ fun App() {
 
             arc(pointOne, Distance(10.0), 0f, PI)
 
-            line(pointOne, pointTwo)
+            line(pointOne, pointTwo, id = "line")
             text(pointOne, "Home", font = { size = 32f })
 
             centerCoordinates?.let {

maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/MapView.kt

@@ -11,10 +11,15 @@ import kotlin.math.min
 
 
 //TODO consider replacing by modifier
+/**
+ * @param onDrag - returns true if you want to drag a map and false, if you want to make map stationary.
+ *          start - is a point where drag begins, end is a point where drag ends
+ */
 public data class MapViewConfig(
     val zoomSpeed: Double = 1.0 / 3.0,
     val inferViewBoxFromFeatures: Boolean = false,
     val onClick: MapViewPoint.() -> Unit = {},
+    val onDrag: (start: MapViewPoint, end: MapViewPoint) -> Boolean = { _, _ -> true },
     val onViewChange: MapViewPoint.() -> Unit = {},
     val onSelect: (GmcBox) -> Unit = {},
     val zoomOnSelect: Boolean = true,

maps-kt-compose/src/jvmMain/kotlin/center/sciprog/maps/compose/MapViewJvm.kt

@@ -146,6 +146,14 @@ public actual fun MapView(
                             config.onClick(MapViewPoint(dpPos.toGeodetic(), viewPoint.zoom))
                             drag(change.id) { dragChange ->
                                 val dragAmount = dragChange.position - dragChange.previousPosition
+                                val dpStart =
+                                    DpOffset(dragChange.previousPosition.x.toDp(), dragChange.previousPosition.y.toDp())
+                                val dpEnd = DpOffset(dragChange.position.x.toDp(), dragChange.position.y.toDp())
+                                if (!config.onDrag(
+                                        MapViewPoint(dpStart.toGeodetic(), viewPoint.zoom),
+                                        MapViewPoint(dpEnd.toGeodetic(), viewPoint.zoom)
+                                    )
+                                ) return@drag
                                 val newViewPoint = viewPoint.move(
                                     -dragAmount.x.toDp().value / tileScale,
                                     +dragAmount.y.toDp().value / tileScale