feat: hovering with the mouse highlights cells (closes #34)

alt-tab-macos/ui/Application.swift

@@ -102,7 +102,7 @@ class Application: NSApplication, NSApplicationDelegate, NSWindowDelegate {
 
     func cycleSelection(_ step: Int) {
         selectedOpenWindow = cellWithStep(step)
-        thumbnailsPanel!.highlightCell(step)
+        thumbnailsPanel!.highlightCellAt(step)
     }
 
     func showUiOrCycleSelection(_ step: Int) {

alt-tab-macos/ui/Cell.swift

@@ -1,23 +1,15 @@
 import Cocoa
 
+typealias MouseDownCallback = (OpenWindow) -> Void
+typealias MouseMovedCallback = (Cell) -> Void
+
 class Cell: NSCollectionViewItem {
     var thumbnail = NSImageView()
     var icon = NSImageView()
     var label = CellTitle()
     var openWindow: OpenWindow?
-    var mouseDownCallback: ((OpenWindow) -> Void)?
-
-    static func makeShadow(_ color: NSColor) -> NSShadow {
-        let shadow = NSShadow()
-        shadow.shadowColor = color
-        shadow.shadowOffset = NSMakeSize(0, 0)
-        shadow.shadowBlurRadius = 1
-        return shadow
-    }
-
-    override func mouseDown(with theEvent: NSEvent) {
-        mouseDownCallback!(openWindow!)
-    }
+    var mouseDownCallback: MouseDownCallback?
+    var mouseMovedCallback: MouseMovedCallback?
 
     override func loadView() {
         let hStackView = makeHStackView()
@@ -28,6 +20,52 @@ class Cell: NSCollectionViewItem {
         view = vStackView
     }
 
+    override func mouseMoved(with event: NSEvent) {
+        mouseMovedCallback!(self)
+    }
+
+    override func mouseDown(with theEvent: NSEvent) {
+        mouseDownCallback!(openWindow!)
+    }
+
+    override var isSelected: Bool {
+        didSet {
+            view.layer!.backgroundColor = isSelected ? Preferences.highlightBackgroundColor!.cgColor : .clear
+            view.layer!.borderColor = isSelected ? Preferences.highlightBorderColor!.cgColor : .clear
+        }
+    }
+
+
+
+    func updateWithNewContent(_ element: OpenWindow, _ mouseDownCallback: @escaping MouseDownCallback, _ mouseMovedCallback: @escaping MouseMovedCallback) {
+        openWindow = element
+        thumbnail.image = element.thumbnail
+        let (width, height) = computeDownscaledSize(element.thumbnail)
+        thumbnail.image!.size = NSSize(width: width, height: height)
+        thumbnail.frame.size = NSSize(width: width, height: height)
+        icon.image = element.icon
+        icon.image?.size = NSSize(width: Preferences.iconSize!, height: Preferences.iconSize!)
+        icon.frame.size = NSSize(width: Preferences.iconSize!, height: Preferences.iconSize!)
+        label.string = element.cgTitle
+        // workaround: setting string on NSTextView change the font (most likely a Cocoa bug)
+        label.font = Preferences.font!
+        label.textContainer!.size.width = thumbnail.frame.size.width - Preferences.iconSize! - Preferences.interItemPadding
+        self.mouseDownCallback = mouseDownCallback
+        self.mouseMovedCallback = mouseMovedCallback
+        if view.trackingAreas.count > 0 {
+            view.removeTrackingArea(view.trackingAreas[0])
+        }
+        view.addTrackingArea(NSTrackingArea(rect: view.bounds, options: [.mouseMoved, .activeAlways], owner: self, userInfo: nil))
+    }
+
+    static func makeShadow(_ color: NSColor) -> NSShadow {
+        let shadow = NSShadow()
+        shadow.shadowColor = color
+        shadow.shadowOffset = NSMakeSize(0, 0)
+        shadow.shadowBlurRadius = 1
+        return shadow
+    }
+
     private func makeHStackView() -> NSStackView {
         let hStackView = NSStackView()
         hStackView.spacing = Preferences.interItemPadding
@@ -50,27 +88,4 @@ class Cell: NSCollectionViewItem {
         vStackView.addView(thumbnail, in: .leading)
         return vStackView
     }
-
-    override var isSelected: Bool {
-        didSet {
-            view.layer!.backgroundColor = isSelected ? Preferences.highlightBackgroundColor!.cgColor : .clear
-            view.layer!.borderColor = isSelected ? Preferences.highlightBorderColor!.cgColor : .clear
-        }
-    }
-
-    func updateWithNewContent(_ element: OpenWindow, _ fn: @escaping (OpenWindow) -> Void) {
-        openWindow = element
-        thumbnail.image = element.thumbnail
-        let (width, height) = computeDownscaledSize(element.thumbnail)
-        thumbnail.image!.size = NSSize(width: width, height: height)
-        thumbnail.frame.size = NSSize(width: width, height: height)
-        icon.image = element.icon
-        icon.image?.size = NSSize(width: Preferences.iconSize!, height: Preferences.iconSize!)
-        icon.frame.size = NSSize(width: Preferences.iconSize!, height: Preferences.iconSize!)
-        label.string = element.cgTitle
-        // workaround: setting string on NSTextView change the font (most likely a Cocoa bug)
-        label.font = Preferences.font!
-        label.textContainer!.size.width = thumbnail.frame.size.width - Preferences.iconSize! - Preferences.interItemPadding
-        mouseDownCallback = fn
-    }
 }

alt-tab-macos/ui/ThumbnailsPanel.swift

@@ -64,7 +64,7 @@ class ThumbnailsPanel: NSPanel, NSCollectionViewDataSource, NSCollectionViewDele
     func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
 //        debugPrint("collectionView: make item", indexPath.item)
         let item = collectionView.makeItem(withIdentifier: cellId, for: indexPath) as! Cell
-        item.updateWithNewContent(application!.openWindows[indexPath.item], application!.focusSelectedWindow)
+        item.updateWithNewContent(application!.openWindows[indexPath.item], application!.focusSelectedWindow, application!.thumbnailsPanel!.highlightCell)
         return item
     }
 
@@ -77,11 +77,20 @@ class ThumbnailsPanel: NSPanel, NSCollectionViewDataSource, NSCollectionViewDele
         return .zero
     }
 
-    func highlightCell(_ step: Int) {
+    func highlightCellAt(_ step: Int) {
         collectionView_!.selectItems(at: [IndexPath(item: application!.selectedOpenWindow, section: 0)], scrollPosition: .top)
         collectionView_!.deselectItems(at: [IndexPath(item: application!.cellWithStep(-step), section: 0)])
     }
 
+    func highlightCell(_ cell: Cell) {
+        let newIndex = collectionView_.indexPath(for: cell)!
+        if application!.selectedOpenWindow != newIndex.item {
+            collectionView_!.selectItems(at: [newIndex], scrollPosition: .top)
+            collectionView_!.deselectItems(at: [IndexPath(item: application!.selectedOpenWindow, section: 0)])
+            application!.selectedOpenWindow = newIndex.item
+        }
+    }
+
     func computeThumbnails() {
         let maxSize = NSSize(width: NSScreen.main!.frame.width * Preferences.maxScreenUsage!, height: NSScreen.main!.frame.height * Preferences.maxScreenUsage!)
         collectionView_!.setFrameSize(maxSize)