feat: fade launcher list edges beneath bars

Sources/Conjure/LauncherWindowController.swift

@@ -257,7 +257,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         }
         tableView.setAccessibilityLabel("Applications")
 
-        let scrollView = NSScrollView()
+        let scrollView = LauncherScrollView()
         scrollView.documentView = tableView
         scrollView.hasVerticalScroller = true
         scrollView.autohidesScrollers = true
@@ -909,6 +909,33 @@ final class ApplicationCell: NSTableCellView {
     }
 }
 
+@MainActor
+final class LauncherScrollView: NSScrollView {
+    private let edgeFade = CAGradientLayer()
+
+    override init(frame frameRect: NSRect) {
+        super.init(frame: frameRect)
+        wantsLayer = true
+        edgeFade.colors = [NSColor.clear.cgColor, NSColor.black.cgColor,
+                           NSColor.black.cgColor, NSColor.clear.cgColor]
+        edgeFade.startPoint = CGPoint(x: 0.5, y: 0)
+        edgeFade.endPoint = CGPoint(x: 0.5, y: 1)
+        layer?.mask = edgeFade
+    }
+
+    required init?(coder: NSCoder) { fatalError("Conjure creates its scroll view programmatically") }
+
+    override func layout() {
+        super.layout()
+        let fade = min(0.5, 16 / max(bounds.height, 1))
+        CATransaction.begin()
+        CATransaction.setDisableActions(true)
+        edgeFade.frame = bounds
+        edgeFade.locations = [0, NSNumber(value: Double(fade)), NSNumber(value: Double(1 - fade)), 1]
+        CATransaction.commit()
+    }
+}
+
 @MainActor
 private final class ApplicationTableView: NSTableView {
     var openSelection: (() -> Void)?