GH-296 Detect drag on buttons

VimR/Workspace/Workspace.swift

@@ -40,6 +40,9 @@ class Workspace: NSView, WorkspaceBarDelegate {
 
   fileprivate var tools = [WorkspaceTool]()
 
+  fileprivate var isDragOngoing = false
+  fileprivate var draggedOnBarLocation: WorkspaceBarLocation?
+
   required init?(coder: NSCoder) {
     fatalError("init(coder:) has not been implemented")
   }
@@ -93,22 +96,28 @@ class Workspace: NSView, WorkspaceBarDelegate {
 extension Workspace {
 
   override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
-//    NSLog("\(#function): \(sender.draggingSource())")
+    self.isDragOngoing = true
     return .move
   }
 
   override func draggingUpdated(_ sender: NSDraggingInfo) -> NSDragOperation {
     let loc = self.convert(sender.draggingLocation(), from: nil)
-
-    if let barLoc = self.bar(inLocation: loc) {
-      NSLog("\(barLoc)")
-    }
+    self.draggedOnBarLocation = self.bar(inLocation: loc)
 
     return .move
   }
 
+  override func draggingExited(_ sender: NSDraggingInfo?) {
+    self.endDrag()
+  }
+
   override func draggingEnded(_ sender: NSDraggingInfo?) {
-//    NSLog("\(#function): \(sender)")
+    self.endDrag()
+  }
+
+  fileprivate func endDrag() {
+    self.isDragOngoing = false
+    self.draggedOnBarLocation = nil
   }
 
   override func prepareForDragOperation(_ sender: NSDraggingInfo) -> Bool {

VimR/Workspace/WorkspaceBar.swift

@@ -25,6 +25,9 @@ class WorkspaceBar: NSView, WorkspaceToolDelegate {
 
   fileprivate var layoutConstraints = [NSLayoutConstraint]()
 
+  fileprivate var isDragOngoing = false
+  fileprivate var draggedOnBarButton: WorkspaceToolButton?
+
   required init?(coder: NSCoder) {
     fatalError("init(coder:) has not been implemented")
   }
@@ -51,6 +54,8 @@ class WorkspaceBar: NSView, WorkspaceToolDelegate {
     super.init(frame: CGRect.zero)
     self.configureForAutoLayout()
 
+    self.register(forDraggedTypes: [WorkspaceToolButton.toolUti])
+
     self.wantsLayer = true
     self.layer!.backgroundColor = NSColor.windowBackgroundColor.cgColor
   }
@@ -115,6 +120,54 @@ class WorkspaceBar: NSView, WorkspaceToolDelegate {
   }
 }
 
+// MARK: - NSDraggingDestination
+extension WorkspaceBar {
+
+  override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
+    self.isDragOngoing = true
+    return .move
+  }
+
+  override func draggingUpdated(_ sender: NSDraggingInfo) -> NSDragOperation {
+    let loc = self.convert(sender.draggingLocation(), from: nil)
+
+    let currentDraggedOnButton = self.tools
+      .map { $0.button }
+      .reduce(nil) { (result, button) -> WorkspaceToolButton? in
+        if result != nil {
+          return result
+        }
+
+        if button.frame.contains(loc) {
+          return button
+        }
+
+        return nil
+    }
+
+    if currentDraggedOnButton == self.draggedOnBarButton {
+      return .move
+    }
+
+    self.draggedOnBarButton = currentDraggedOnButton
+    self.relayout()
+    return .move
+  }
+
+  override func draggingEnded(_ sender: NSDraggingInfo?) {
+    self.endDrag()
+  }
+
+  override func draggingExited(_ sender: NSDraggingInfo?) {
+    self.endDrag()
+  }
+
+  fileprivate func endDrag() {
+    self.isDragOngoing = false
+    self.draggedOnBarButton = nil
+  }
+}
+
 // MARK: - NSView
 extension WorkspaceBar {
 
@@ -446,6 +499,8 @@ extension WorkspaceBar {
   }
 
   fileprivate func layoutButtons() {
+    NSLog("\(#function)")
+
     guard let firstTool = self.tools.first else {
       return
     }

VimR/Workspace/WorkspaceToolButton.swift

@@ -20,6 +20,14 @@ class WorkspaceToolButton: NSView, NSDraggingSource, NSPasteboardItemDataProvide
   // MARK: - API
   static let toolUti = "com.qvacua.vimr.tool"
 
+  static func ==(left: WorkspaceToolButton, right: WorkspaceToolButton) -> Bool {
+    guard let leftTool = left.tool, let rightTool = right.tool else {
+      return false
+    }
+
+    return leftTool == rightTool
+  }
+
   var location = WorkspaceBarLocation.top
   var isSelected: Bool {
     return self.tool?.isSelected ?? false