Merge pull request #45 from li3zhen1/issue-42

Partial fix issue-42: allow drag on canvas
SwiftGraphs · Feb 21, 2024 · e74a32e · e74a32e
2 parents e797789 + 4552950
commit e74a32e
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/Sources/Grape/Views/ForceDirectedGraph+Gesture.swift b/Sources/Grape/Views/ForceDirectedGraph+Gesture.swift
@@ -9,13 +9,15 @@ extension ForceDirectedGraph {
     internal func onDragChange(
         _ value: SwiftUI.DragGesture.Value
     ) {
-        if model.draggingNodeID == nil {
+        if !model.isDragStartStateRecorded {
             if let nodeID = model.findNode(at: value.startLocation) {
                 model.draggingNodeID = nodeID
             } else {
                 model.backgroundDragStart = value.location.simd
             }
+            assert(model.isDragStartStateRecorded == true)
         }
+
         guard let nodeID = model.draggingNodeID else {
             if let dragStart = model.backgroundDragStart {
                 let delta = value.location.simd - dragStart
@@ -51,7 +53,7 @@ extension ForceDirectedGraph {
             if let dragStart = model.backgroundDragStart {
                 let delta = value.location.simd - dragStart
                 model.modelTransform.translate += delta
-                model.backgroundDragStart = value.location.simd
+                model.backgroundDragStart = nil
             }
             return
         }

diff --git a/Sources/Grape/Views/ForceDirectedGraphModel.swift b/Sources/Grape/Views/ForceDirectedGraphModel.swift
@@ -50,6 +50,11 @@ public final class ForceDirectedGraphModel<Content: GraphContent> {
     @usableFromInline
     var backgroundDragStart: SIMD2<Double>? = nil
 
+    @inlinable
+    var isDragStartStateRecorded: Bool {
+        return draggingNodeID != nil || backgroundDragStart != nil 
+    }
+
     @usableFromInline
     let velocityDecay: Double