Add window detection capture with rounded corners

Hovering during selection now highlights the window under the cursor;
clicking captures it with a rounded-corner alpha mask matching macOS
window chrome. Dragging still switches to manual marquee selection.

💘 Generated with Crush

Assisted-by: Crush:deepseek-v4-flash-0731

Sources/Kapture/OverlayView.swift

@@ -1,8 +1,8 @@
 import AppKit
 
 final class OverlayWindow: NSPanel {
-    init(screen: NSScreen, onComplete: @escaping (NSRect) -> Void, onCancel: @escaping () -> Void) {
-        let content = OverlayView(onComplete: onComplete, onCancel: onCancel)
+    init(screen: NSScreen, onComplete: @escaping (NSRect) -> Void, onCancel: @escaping () -> Void, onWindowPick: @escaping (NSRect) -> Void) {
+        let content = OverlayView(onComplete: onComplete, onCancel: onCancel, onWindowPick: onWindowPick)
         super.init(
             contentRect: screen.frame,
             styleMask: [.borderless, .nonactivatingPanel],
@@ -25,13 +25,21 @@ final class OverlayWindow: NSPanel {
 final class OverlayView: NSView {
     private let onComplete: (NSRect) -> Void
     private let onCancel: () -> Void
+    private let onWindowPick: (NSRect) -> Void
 
     private var startPoint: NSPoint?
     private(set) var selection: NSRect?
+    private var isDragging = false
 
-    init(onComplete: @escaping (NSRect) -> Void, onCancel: @escaping () -> Void) {
+    // Window detection
+    private var trackedWindows: [(id: CGWindowID, frame: NSRect)] = []
+    private var hoveredWindowFrame: NSRect?
+    private var excludedIDs: [Int] = []
+
+    init(onComplete: @escaping (NSRect) -> Void, onCancel: @escaping () -> Void, onWindowPick: @escaping (NSRect) -> Void) {
         self.onComplete = onComplete
         self.onCancel = onCancel
+        self.onWindowPick = onWindowPick
         super.init(frame: .zero)
     }
 
@@ -47,6 +55,85 @@ final class OverlayView: NSView {
         addCursorRect(bounds, cursor: .crosshair)
     }
 
+    // MARK: - Window detection
+
+    /// Rebuild the list of capturable windows intersecting this screen.
+    /// Called lazily on mouse moves; cheap enough for interactive hover.
+    private func refreshTrackedWindows() {
+        guard let window = window else { return }
+        let screenFrame = window.convertToScreen(NSRect(origin: .zero, size: bounds.size))
+        // Exclude this overlay's own window (the other overlays don't intersect
+        // this screen, so the on-screen filter handles them).
+        let ownID = window.windowNumber
+
+        guard let list = CGWindowListCopyWindowInfo(
+            [ .optionOnScreenOnly, .excludeDesktopElements ], kCGNullWindowID
+        ) as? [[String: Any]] else { trackedWindows = []; return }
+
+        var found: [(CGWindowID, NSRect)] = []
+        for info in list {
+            guard let cid = info[kCGWindowNumber as String] as? CGWindowID,
+                  let bounds = info[kCGWindowBounds as String] as? [String: CGFloat],
+                  let layer = info[kCGWindowLayer as String] as? Int,
+                  layer == 0
+            else { continue }
+            // Skip our own overlays
+            if Int(cid) == ownID { continue }
+            let rect = NSRect(
+                x: bounds["X"] ?? 0,
+                y: bounds["Y"] ?? 0,
+                width: bounds["Width"] ?? 0,
+                height: bounds["Height"] ?? 0
+            )
+            guard rect.width >= 80, rect.height >= 60 else { continue }
+            // Skip tiny/utility windows
+            guard rect.width < screenFrame.width || rect.height < screenFrame.height else { continue }
+            // Only windows intersecting this screen
+            guard rect.intersects(screenFrame) else { continue }
+            found.append((cid, rect))
+        }
+        trackedWindows = found
+    }
+
+    private func windowFrame(at point: NSPoint) -> NSRect? {
+        guard let window = window else { return nil }
+        let screenPoint = window.convertToScreen(NSRect(origin: point, size: .zero))
+        // CGWindowList bounds use a TOP-LEFT origin; convert the cursor point.
+        guard let mainScreen = NSScreen.screens.first else { return nil }
+        let topLeftPoint = NSPoint(
+            x: screenPoint.origin.x,
+            y: mainScreen.frame.height - screenPoint.origin.y
+        )
+        // Pick the frontmost (list order) window containing the point
+        for (_, frame) in trackedWindows {
+            if frame.contains(topLeftPoint) {
+                return frame
+            }
+        }
+        return nil
+    }
+
+    /// Convert a CGWindowList (top-left origin) frame into AppKit screen
+    /// coordinates (bottom-left origin) for capture.
+    private static func cgToAppKit(rect: NSRect) -> NSRect {
+        guard let mainScreen = NSScreen.screens.first else { return rect }
+        let y = mainScreen.frame.height - rect.origin.y - rect.height
+        return NSRect(x: rect.origin.x, y: y, width: rect.width, height: rect.height)
+    }
+
+    // MARK: - Events
+
+    override func mouseMoved(with event: NSEvent) {
+        guard !isDragging else { return }
+        refreshTrackedWindows()
+        let p = convert(event.locationInWindow, from: nil)
+        let frame = windowFrame(at: p)
+        if frame != hoveredWindowFrame {
+            hoveredWindowFrame = frame
+            needsDisplay = true
+        }
+    }
+
     override func mouseDown(with event: NSEvent) {
         let p = convert(event.locationInWindow, from: nil)
         startPoint = p
@@ -56,6 +143,8 @@ final class OverlayView: NSView {
 
     override func mouseDragged(with event: NSEvent) {
         guard let start = startPoint else { return }
+        isDragging = true
+        hoveredWindowFrame = nil
         let p = convert(event.locationInWindow, from: nil)
         selection = NSRect(
             x: min(start.x, p.x),
@@ -67,9 +156,20 @@ final class OverlayView: NSView {
     }
 
     override func mouseUp(with event: NSEvent) {
-        guard let sel = selection else { return }
-        if sel.width >= 2, sel.height >= 2 {
-            onComplete(window!.convertToScreen(sel))
+        if isDragging {
+            guard let sel = selection else { return }
+            if sel.width >= 2, sel.height >= 2 {
+                onComplete(window!.convertToScreen(sel))
+            } else {
+                onCancel()
+            }
+            return
+        }
+
+        // No drag: it was a click. If a window is hovered, capture it with
+        // rounded corners; otherwise treat as an empty marquee (cancel).
+        if let frame = hoveredWindowFrame {
+            onWindowPick(Self.cgToAppKit(rect: frame))
         } else {
             onCancel()
         }
@@ -87,6 +187,30 @@ final class OverlayView: NSView {
         NSColor.black.withAlphaComponent(0.35).setFill()
         NSBezierPath(rect: bounds).fill()
 
+        // Highlight the hovered window (rounded, like the real window corners)
+        if let frame = hoveredWindowFrame {
+            // Convert CGWindowList (top-left) frame to view (bottom-left) space
+            guard let window = window, let mainScreen = NSScreen.screens.first else { return }
+            let screenFrame = window.convertToScreen(NSRect(origin: .zero, size: bounds.size))
+            let viewFrame = NSRect(
+                x: frame.origin.x - screenFrame.origin.x,
+                y: mainScreen.frame.height - frame.origin.y - frame.height - screenFrame.origin.y,
+                width: frame.width,
+                height: frame.height
+            )
+            NSGraphicsContext.current?.saveGraphicsState()
+            NSGraphicsContext.current?.compositingOperation = .clear
+            NSColor.black.setFill()
+            NSBezierPath(roundedRect: viewFrame, xRadius: 10, yRadius: 10).fill()
+            NSGraphicsContext.current?.restoreGraphicsState()
+
+            let border = NSBezierPath(roundedRect: viewFrame, xRadius: 10, yRadius: 10)
+            border.lineWidth = 2
+            NSColor.controlAccentColor.setStroke()
+            border.stroke()
+            return
+        }
+
         guard let sel = selection, sel.width > 0, sel.height > 0 else { return }
 
         NSGraphicsContext.current?.saveGraphicsState()