Cleanup drag

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

@@ -76,22 +76,19 @@ fun App() {
                 line(drag3, drag1, id = "connection3", color = Color.Magenta)
             }
 
-            rectangle(drag1, size = DpSize(10.dp, 10.dp)).draggable { _, _, end ->
+            rectangle(drag1, size = DpSize(10.dp, 10.dp)).draggable { _, end ->
-                drag1 = end.focus
+                drag1 = end
                 updateLine()
-                true
             }
 
-            rectangle(drag2, size = DpSize(10.dp, 10.dp)).draggable { _, _, end ->
+            rectangle(drag2, size = DpSize(10.dp, 10.dp)).draggable { _, end ->
-                drag2 = end.focus
+                drag2 = end
                 updateLine()
-                true
             }
 
-            rectangle(drag3, size = DpSize(10.dp, 10.dp)).draggable { _, _, end ->
+            rectangle(drag3, size = DpSize(10.dp, 10.dp)).draggable { _, end ->
-                drag3 = end.focus
+                drag3 = end
                 updateLine()
-                true
             }
 
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

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

@@ -87,17 +87,24 @@ public fun MapView(
     val viewPointOverride: MapViewPoint = remember(initialViewPoint, initialRectangle) {
         initialViewPoint
             ?: initialRectangle?.computeViewPoint(mapTileProvider)
-            ?: featureState.features.values.computeBoundingBox(GmcCoordinateSpace,1f)?.computeViewPoint(mapTileProvider)
+            ?: featureState.features.values.computeBoundingBox(GmcCoordinateSpace, 1f)
+                ?.computeViewPoint(mapTileProvider)
             ?: MapViewPoint.globe
     }
 
-    val featureDrag: DragHandle<Gmc> = DragHandle.withPrimaryButton { event, start: ViewPoint<Gmc>, end: ViewPoint<Gmc> ->
+    val featureDrag: DragHandle<Gmc> = DragHandle.withPrimaryButton { event, start, end ->
         featureState.forEachWithAttribute(DraggableAttribute) { _, handle ->
-            //TODO add safety
+            @Suppress("UNCHECKED_CAST")
-            handle as DragHandle<Gmc>
+            (handle as DragHandle<Gmc>)
-            if (!handle.handle(event, start, end)) return@withPrimaryButton false
+                .handle(event, start, end)
+                .takeIf { !it.handleNext }
+                ?.let {
+                    //we expect it already have no bypass
+                    return@withPrimaryButton it
                 }
-        true
+        }
+        //bypass
+        DragResult(end)
     }
 
 

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

@@ -127,7 +127,7 @@ public actual fun MapView(
                     )
                 }
 
-                featuresState.features.values.filter { viewPoint.zoom in it.zoomRange }.sortedBy { it.depth }.forEach { feature ->
+                featuresState.features.values.filter { viewPoint.zoom in it.zoomRange }.sortedBy { it.z }.forEach { feature ->
                     drawFeature(state, painterCache, feature)
                 }
             }

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/AttributeMap.kt

@@ -3,9 +3,9 @@ package center.sciprog.maps.features
 import androidx.compose.runtime.mutableStateMapOf
 import androidx.compose.ui.graphics.Color
 
-public object DepthAttribute : Feature.Attribute<Float>
+public object ZAttribute : Feature.Attribute<Float>
 
-public object DraggableAttribute : Feature.Attribute<DragHandle<*>>
+public object DraggableAttribute : Feature.Attribute<DragHandle<Any>>
 
 public object SelectableAttribute : Feature.Attribute<(FeatureId<*>, SelectableFeature<*>) -> Unit>
 
@@ -46,8 +46,8 @@ public class AttributeMap {
     override fun toString(): String = "AttributeMap(value=${map.entries})"
 }
 
-public var Feature<*>.depth: Float
+public var Feature<*>.z: Float
-    get() = attributes[DepthAttribute] ?: 0f
+    get() = attributes[ZAttribute] ?: 0f
     set(value) {
-        attributes[DepthAttribute] = value
+        attributes[ZAttribute] = value
     }

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/DragHandle.kt

@@ -3,7 +3,13 @@ package center.sciprog.maps.features
 import androidx.compose.ui.input.pointer.PointerEvent
 import androidx.compose.ui.input.pointer.isPrimaryPressed
 
-public fun interface DragHandle<T: Any>{
+/**
+ * @param result - the endpoint of the drag to perform constrained drag
+ * @param handleNext - if false do not evaluate subsequent drag handles
+ */
+public data class DragResult<T : Any>(val result: ViewPoint<T>, val handleNext: Boolean = true)
+
+public fun interface DragHandle<T : Any> {
     /**
      * @param event - qualifiers of the event used for drag
      * @param start - is a point where drag begins, end is a point where drag ends
@@ -11,32 +17,36 @@ public fun interface DragHandle<T: Any>{
      *
      * @return true if default event processors should be used after this one
      */
-    public fun handle(event: PointerEvent, start: ViewPoint<T>, end: ViewPoint<T>): Boolean
+    public fun handle(event: PointerEvent, start: ViewPoint<T>, end: ViewPoint<T>): DragResult<T>
 
     public companion object {
-        public fun <T: Any> bypass(): DragHandle<T> = DragHandle<T> { _, _, _ -> true }
+        public fun <T : Any> bypass(): DragHandle<T> = DragHandle<T> { _, _, end -> DragResult(end) }
 
         /**
          * Process only events with primary button pressed
          */
-        public fun <T: Any> withPrimaryButton(
+        public fun <T : Any> withPrimaryButton(
-            block: (event: PointerEvent, start: ViewPoint<T>, end: ViewPoint<T>) -> Boolean,
+            block: (event: PointerEvent, start: ViewPoint<T>, end: ViewPoint<T>) -> DragResult<T>,
         ): DragHandle<T> = DragHandle { event, start, end ->
             if (event.buttons.isPrimaryPressed) {
                 block(event, start, end)
             } else {
-                true
+                DragResult(end)
             }
         }
 
         /**
          * Combine several handles into one
          */
-        public fun <T: Any> combine(vararg handles: DragHandle<T>): DragHandle<T> = DragHandle { event, start, end ->
+        public fun <T : Any> combine(vararg handles: DragHandle<T>): DragHandle<T> = DragHandle { event, start, end ->
+            var current: ViewPoint<T> = end
             handles.forEach {
-                if (!it.handle(event, start, end)) return@DragHandle false
+                val result = it.handle(event, start, current)
+                if (!result.handleNext) return@DragHandle result else {
+                    current = result.result
                 }
-            return@DragHandle true
+            }
+            return@DragHandle DragResult(current)
         }
     }
 }

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/FeaturesState.kt

@@ -44,23 +44,33 @@ public class FeaturesState<T : Any>(public val coordinateSpace: CoordinateSpace<
 
 
     public fun <F : Feature<T>, V> setAttribute(id: FeatureId<F>, key: Feature.Attribute<V>, value: V?) {
-        getFeature(id).attributes.set(key, value)
+        getFeature(id).attributes[key] = value
     }
 
-    //TODO use context receiver for that
+    /**
+     * Add drag to this feature
+     *
+     * @param constraint optional drag constraint
+     *
+     * TODO use context receiver for that
+     */
     public fun FeatureId<DraggableFeature<T>>.draggable(
-        //TODO add constraints
+        constraint: ((T) -> T)? = null,
-        callback: DragHandle<T> = DragHandle.bypass(),
+        callback: ((start: T, end: T) -> Unit) = { _, _ -> },
     ) {
-        val handle = DragHandle.withPrimaryButton<T> { event, start, end ->
+        @Suppress("UNCHECKED_CAST")
-            val feature = featureMap[id] as? DraggableFeature ?: return@withPrimaryButton true
+        val handle = DragHandle.withPrimaryButton<Any> { _, start, end ->
-            val boundingBox = feature.getBoundingBox(start.zoom) ?: return@withPrimaryButton true
+            val startPosition = start.focus as T
-            if (start.focus in boundingBox) {
+            val endPosition = end.focus as T
-                feature(id, feature.withCoordinates(end.focus))
+            val feature = featureMap[id] as? DraggableFeature ?: return@withPrimaryButton DragResult(end)
-                callback.handle(event, start, end)
+            val boundingBox = feature.getBoundingBox(start.zoom) ?: return@withPrimaryButton DragResult(end)
-                false
+            if (startPosition in boundingBox) {
+                val finalPosition = constraint?.invoke(endPosition) ?: endPosition
+                feature(id, feature.withCoordinates(finalPosition))
+                callback(startPosition, finalPosition)
+                DragResult(ViewPoint(finalPosition, end.zoom), false)
             } else {
-                true
+                DragResult(end, true)
             }
         }
         setAttribute(this, DraggableAttribute, handle)
@@ -98,11 +108,14 @@ public class FeaturesState<T : Any>(public val coordinateSpace: CoordinateSpace<
 //        }.keys
 //    }
 
+    /**
+     * Process all features with a given attribute from the one with highest [z] to lowest
+     */
     public inline fun <A> forEachWithAttribute(
         key: Feature.Attribute<A>,
         block: (id: FeatureId<*>, attributeValue: A) -> Unit,
     ) {
-        featureMap.forEach { (id, feature) ->
+        featureMap.entries.sortedByDescending { it.value.z }.forEach { (id, feature) ->
             feature.attributes[key]?.let {
                 block(FeatureId<Feature<T>>(id), it)
             }

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/ViewPoint.kt

@@ -3,7 +3,7 @@ package center.sciprog.maps.features
 /**
  * @param T type of coordinates used for the view point
  */
-public interface ViewPoint<T: Any> {
+public interface ViewPoint<out T: Any> {
     public val focus: T
     public val zoom: Float
 }

maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/compose/mapControls.kt

@@ -44,13 +44,13 @@ public fun <T : Any> Modifier.mapControls(
                         val dpEnd = dragChange.position.toDpOffset()
 
                         //apply drag handle and check if it prohibits the drag even propagation
-                        if (selectionStart == null && !config.dragHandle.handle(
+                        if (selectionStart == null) {
+                            val dragResult = config.dragHandle.handle(
                                 event,
                                 space.ViewPoint(dpStart.toCoordinates(), viewPoint.zoom),
                                 space.ViewPoint(dpEnd.toCoordinates(), viewPoint.zoom)
                             )
-                        ) {
+                            if(!dragResult.handleNext) return@drag
-                            return@drag
                         }
 
                         if (event.buttons.isPrimaryPressed) {

maps-kt-scheme/src/commonMain/kotlin/center/sciprog/maps/scheme/schemeFeatures.kt

@@ -26,7 +26,7 @@ fun FeaturesState<XY>.background(
     return feature(
         id,
         ScalableImageFeature(coordinateSpace, box, painter = painter).apply {
-            depth = -100f
+            z = -100f
         }
     )
 }

maps-kt-scheme/src/jvmMain/kotlin/center/sciprog/maps/scheme/SchemeView.kt

@@ -50,7 +50,7 @@ public fun SchemeView(
             clipRect {
                 featuresState.features.values
                     .filter { viewPoint.zoom in it.zoomRange }
-                    .sortedBy { it.depth }
+                    .sortedBy { it.z }
                     .forEach { background ->
                         drawFeature(state, painterCache, background)
                     }
@@ -139,10 +139,12 @@ public fun SchemeView(
         DragHandle.withPrimaryButton { event, start: ViewPoint<XY>, end: ViewPoint<XY> ->
             featureState.forEachWithAttribute(DraggableAttribute) { _, handle ->
                 //TODO add safety
-                handle as DragHandle<XY>
+                (handle as DragHandle<XY>)
-                if (!handle.handle(event, start, end)) return@withPrimaryButton false
+                    .handle(event, start, end)
+                    .takeIf { !it.handleNext }
+                    ?.let { return@withPrimaryButton it }
             }
-            true
+            DragResult(end)
         }