More robust drag API and implementation

gradle.properties

@@ -1,8 +1,8 @@
 kotlin.code.style=official
 
-compose.version=1.2.0
+compose.version=1.2.1
 
 agp.version=4.2.2
 android.useAndroidX=true
 
-toolsVersion=0.13.1-kotlin-1.7.20
+toolsVersion=0.13.3-kotlin-1.7.20

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

@@ -14,7 +14,7 @@ import center.sciprog.maps.coordinates.*
 
 public typealias FeatureId = String
 
-public object DraggableAttribute : MapFeaturesState.Attribute<Boolean>
+public object DraggableAttribute : MapFeaturesState.Attribute<DragHandle>
 
 public class MapFeaturesState internal constructor(
     private val features: MutableMap<FeatureId, MapFeature>,
@@ -23,9 +23,24 @@ public class MapFeaturesState internal constructor(
     public interface Attribute<T>
 
     //TODO use context receiver for that
-    public fun FeatureId.draggable(enabled: Boolean = true) {
-        setAttribute(this, DraggableAttribute, enabled)
+    public fun FeatureId.draggable(
+        //TODO add constraints
+        callback: DragHandle = DragHandle.BYPASS
+    ) {
+        val handle = DragHandle.withPrimaryButton { event, start, end ->
+            val feature = features[this] as? DraggableMapFeature ?: return@withPrimaryButton true
+            val boundingBox = feature.getBoundingBox(start.zoom) ?: return@withPrimaryButton true
+            if (start.focus in boundingBox) {
+                addFeature(this, feature.withCoordinates(end.focus))
+                callback.handle(event, start, end)
+                false
+            } else {
+                true
             }
+        }
+        setAttribute(this, DraggableAttribute, handle)
+    }
+
 
     public fun features(): Map<FeatureId, MapFeature> = features
 
@@ -42,17 +57,31 @@ public class MapFeaturesState internal constructor(
         attributes.getOrPut(id) { mutableStateMapOf() }[key] = value
     }
 
+    public fun removeAttribute(id: FeatureId, key: Attribute<*>) {
+        attributes[id]?.remove(key)
+    }
+
     @Suppress("UNCHECKED_CAST")
     public fun <T> getAttribute(id: FeatureId, key: Attribute<T>): T? =
         attributes[id]?.get(key)?.let { it as T }
 
+//    @Suppress("UNCHECKED_CAST")
+//    public fun <T> findAllWithAttribute(key: Attribute<T>, condition: (T) -> Boolean): Set<FeatureId> {
+//        return attributes.filterValues {
+//            condition(it[key] as T)
+//        }.keys
+//    }
+
+    public fun <T> forEachWithAttribute(key: Attribute<T>, block: (id: FeatureId, attributeValue: T) -> Unit) {
+        attributes.forEach { (id, attributeMap) ->
+            attributeMap[key]?.let {
                 @Suppress("UNCHECKED_CAST")
-    public fun <T> findAllWithAttribute(key: Attribute<T>, condition: (T) -> Boolean): Set<FeatureId> {
-        return attributes.filterValues {
-            condition(it[key] as T)
-        }.keys
+                block(id, it as T)
             }
-    public companion object{
+        }
+    }
+
+    public companion object {
 
         /**
          * Build, but do not remember map feature state

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

@@ -37,7 +37,7 @@ public fun interface DragHandle {
             if (event.buttons.isPrimaryPressed) {
                 block(event, start, end)
             } else {
-                false
+                true
             }
         }
 
@@ -145,17 +145,12 @@ public fun MapView(
             ?: MapViewPoint.globe
     }
 
-    val featureDrag = DragHandle.withPrimaryButton { _, start, end ->
-        val zoom = start.zoom
-        featureState.findAllWithAttribute(DraggableAttribute) { it }.forEach { id ->
-            val feature = features[id] as? DraggableMapFeature ?: return@forEach
-            val boundingBox = feature.getBoundingBox(zoom) ?: return@forEach
-            if (start.focus in boundingBox) {
-                featureState.addFeature(id, feature.withCoordinates(end.focus))
-                return@withPrimaryButton false
+    val featureDrag: DragHandle = DragHandle.withPrimaryButton { event, start, end ->
+        var bypass = true
+        featureState.forEachWithAttribute(DraggableAttribute) { _, handle ->
+            bypass = bypass and handle.handle(event, start, end)
         }
-        }
-        return@withPrimaryButton true
+        bypass
     }
 
 

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

@@ -112,11 +112,8 @@ public actual fun MapView(
 
                     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())
+                        val dpStart = dragChange.previousPosition.toDpOffset()
+                        val dpEnd = dragChange.position.toDpOffset()
 
                         //apply drag handle and check if it prohibits the drag even propagation
                         if (