small autozoom fix

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

@@ -49,7 +49,7 @@ fun MapView(
     )
 }
 
-internal fun GmcBox.getComputeViewPoint(mapTileProvider: MapTileProvider): (canvasSize: DpSize) -> MapViewPoint = { canvasSize ->
+internal fun GmcBox.computeViewPoint(mapTileProvider: MapTileProvider): (canvasSize: DpSize) -> MapViewPoint = { canvasSize ->
     val zoom = log2(
         min(
             canvasSize.width.value / width,
@@ -72,7 +72,7 @@ fun MapView(
     featuresBuilder.buildFeatures()
     MapView(
         mapTileProvider,
-        box.getComputeViewPoint(mapTileProvider),
+        box.computeViewPoint(mapTileProvider),
         featuresBuilder.build(),
         config,
         modifier

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

@@ -17,7 +17,7 @@ import androidx.compose.ui.graphics.toArgb
 import androidx.compose.ui.input.pointer.*
 import androidx.compose.ui.unit.*
 import centre.sciprog.maps.*
-import io.ktor.utils.io.CancellationException
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.launch
 import mu.KotlinLogging
 import org.jetbrains.skia.Font
@@ -59,9 +59,12 @@ actual fun MapView(
 ) {
     var canvasSize by remember { mutableStateOf(DpSize(512.dp, 512.dp)) }
 
-    var viewPointOverride: MapViewPoint? by remember {
+    var viewPointInternal: MapViewPoint? by remember {
-        mutableStateOf(
+        mutableStateOf(null)
-            if (config.inferViewBoxFromFeatures) {
+    }
+
+    val viewPoint: MapViewPoint by derivedStateOf {
+        viewPointInternal ?: if (config.inferViewBoxFromFeatures) {
             features.values.computeBoundingBox(1)?.let { box ->
                 val zoom = log2(
                     min(
@@ -70,15 +73,12 @@ actual fun MapView(
                     ) * PI / mapTileProvider.tileSize
                 )
                 MapViewPoint(box.center, zoom)
-                }
+            } ?: computeViewPoint(canvasSize)
         } else {
-                null
+            computeViewPoint(canvasSize)
         }
-        )
     }
 
-    val viewPoint by derivedStateOf { viewPointOverride ?: computeViewPoint(canvasSize) }
-
     val zoom: Int by derivedStateOf { floor(viewPoint.zoom).toInt() }
 
     val tileScale: Double by derivedStateOf { 2.0.pow(viewPoint.zoom - zoom) }
@@ -132,10 +132,10 @@ actual fun MapView(
                                 )
                                 config.onSelect(gmcBox)
                                 if (config.zoomOnSelect) {
-                                    val newViewPoint = gmcBox.getComputeViewPoint(mapTileProvider).invoke(canvasSize)
+                                    val newViewPoint = gmcBox.computeViewPoint(mapTileProvider).invoke(canvasSize)
 
                                     config.onViewChange(newViewPoint)
-                                    viewPointOverride = newViewPoint
+                                    viewPointInternal = newViewPoint
                                 }
                                 selectRect = null
                             }
@@ -150,7 +150,7 @@ actual fun MapView(
                                     +dragAmount.y.toDp().value / tileScale
                                 )
                                 config.onViewChange(newViewPoint)
-                                viewPointOverride = newViewPoint
+                                viewPointInternal = newViewPoint
                             }
                         }
                     }
@@ -164,7 +164,7 @@ actual fun MapView(
         val invariant = DpOffset(xPos.toDp(), yPos.toDp()).toGeodetic()
         val newViewPoint = viewPoint.zoom(-change.scrollDelta.y.toDouble() * config.zoomSpeed, invariant)
         config.onViewChange(newViewPoint)
-        viewPointOverride = newViewPoint
+        viewPointInternal = newViewPoint
     }.fillMaxSize()