Fix vertical offset when capturing the secondary display

The first ScreenCaptureKit Y-flip used the wrong reference edges, shifting
cropped selections on displays below the main screen. Convert each selection
per-display as scY = appKitY - NSScreen.maxY + SCDisplay.maxY, which
matches both the main and secondary displays.

💘 Generated with Crush

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

Sources/Kapture/App.swift

@@ -48,6 +48,13 @@ struct MenuView: View {
 
         Divider()
 
+        Button("Copy Diagnostics") {
+            let diag = CaptureController.shared.diagnostics()
+            let pasteboard = NSPasteboard.general
+            pasteboard.clearContents()
+            pasteboard.setString(diag, forType: .string)
+        }
+
         Button(LoginItem.isEnabled ? "Disable Launch at Login" : "Launch at Login") {
             if !LoginItem.toggle() {
                 let alert = NSAlert()

Sources/Kapture/CaptureController.swift

@@ -10,6 +10,38 @@ final class CaptureController: NSObject {
     private var previousApp: NSRunningApplication?
     private var overlayIDs: [Int] = []
 
+    /// Diagnostic snapshot for "Copy Diagnostics" menu item.
+    func diagnostics() -> String {
+        var lines: [String] = []
+        lines.append("Kapture diagnostics")
+        for (i, s) in NSScreen.screens.enumerated() {
+            let scale = s.backingScaleFactor
+            let cgID = (s.deviceDescription[NSDeviceDescriptionKey("NSScreenNumber")] as? NSNumber)?.uint32Value ?? 0
+            lines.append("screen[\(i)]: frame=\(s.frame) scale=\(scale) backingSize=\(s.frame.width*scale)x\(s.frame.height*scale) cgID=\(cgID)")
+        }
+        if #available(macOS 14.0, *) {
+            Task {
+                if let content = try? await SCShareableContent.current {
+                    for (i, d) in content.displays.enumerated() {
+                        lines.append("SCDisplay[\(i)]: frame=\(d.frame) width=\(d.width)x\(d.height) id=\(d.displayID)")
+                    }
+                } else {
+                    lines.append("SCShareableContent: unavailable (no Screen Recording permission?)")
+                }
+                let text = lines.joined(separator: "\n")
+                let pb = NSPasteboard.general
+                pb.clearContents()
+                pb.setString(text, forType: .string)
+            }
+        } else {
+            let text = lines.joined(separator: "\n")
+            let pb = NSPasteboard.general
+            pb.clearContents()
+            pb.setString(text, forType: .string)
+        }
+        return lines.joined(separator: "\n")
+    }
+
     func begin() {
         guard !isSelecting else { return }
         guard PermissionManager.isGranted else {
@@ -85,29 +117,31 @@ final class ScreenCapture {
     private init() {}
 
     @available(macOS 14.0, *)
-    private func crop(_ image: CGImage, to rect: NSRect, display: SCDisplay) -> CGImage? {
-        let scaleX = CGFloat(display.width) / display.frame.width
-        let scaleY = CGFloat(display.height) / display.frame.height
-        let cgRect = CGRect(
-            x: rect.minX,
-            y: rect.minY,
-            width: rect.width,
-            height: rect.height
-        )
+    private func crop(_ image: CGImage, to cgRect: CGRect, display: SCDisplay) -> CGImage? {
+        // cgRect is already in SCDisplay space (Y flipped relative to AppKit).
+        // Derive the pixel scale from the image we actually got, relative to
+        // the display's point frame.
+        let scaleX = CGFloat(image.width) / display.frame.width
+        let scaleY = CGFloat(image.height) / display.frame.height
+        guard scaleX > 0, scaleY > 0 else { return nil }
         let pxRect = CGRect(
             x: (cgRect.minX - display.frame.minX) * scaleX,
             y: (cgRect.minY - display.frame.minY) * scaleY,
             width: cgRect.width * scaleX,
             height: cgRect.height * scaleY
         )
+        // Guard against negative offsets when the selection reaches beyond the
+        // display's frame (e.g. secondary monitor coordinate quirks).
+        let safeRect = pxRect.intersection(CGRect(x: 0, y: 0, width: CGFloat(image.width), height: CGFloat(image.height)))
+        guard safeRect.width >= 1, safeRect.height >= 1 else { return nil }
         guard let cropCtx = CGContext(
-            data: nil, width: Int(pxRect.width), height: Int(pxRect.height),
+            data: nil, width: Int(safeRect.width), height: Int(safeRect.height),
             bitsPerComponent: 8, bytesPerRow: 0,
             space: CGColorSpaceCreateDeviceRGB(),
             bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
         ) else { return nil }
         cropCtx.interpolationQuality = .high
-        cropCtx.draw(image, in: CGRect(x: -pxRect.minX, y: -pxRect.minY, width: CGFloat(image.width), height: CGFloat(image.height)))
+        cropCtx.draw(image, in: CGRect(x: -safeRect.minX, y: -safeRect.minY, width: CGFloat(image.width), height: CGFloat(image.height)))
         return cropCtx.makeImage()
     }
 
@@ -133,15 +167,34 @@ final class ScreenCapture {
                 let excluded = content.windows.filter { excludedSet.contains($0.windowID) }
                 let filter = SCContentFilter(display: display, excludingWindows: excluded)
                 let config = SCStreamConfiguration()
-                config.width = Int(display.width)
-                config.height = Int(display.height)
+                // SCDisplay.width/height are in POINTS; SCStreamConfiguration
+                // width/height are output PIXELS. Multiply by the backing scale
+                // of the screen containing the selection so retina displays are
+                // captured at full resolution and 1x displays stay 1x.
+                guard let screen = NSScreen.screens.first(where: { $0.frame.contains(NSPoint(x: rect.midX, y: rect.midY)) }) else {
+                    completion(nil)
+                    return
+                }
+                let backingScale = screen.backingScaleFactor
+                config.width = Int(CGFloat(display.width) * backingScale)
+                config.height = Int(CGFloat(display.height) * backingScale)
                 config.showsCursor = true
 
+                // ScreenCaptureKit uses a different origin than AppKit for
+                // screens stacked around the main display: per-display,
+                // SCDisplay y = appKitY - NSScreen.maxY + SCDisplay.maxY.
+                let scRect = CGRect(
+                    x: rect.minX,
+                    y: rect.minY - screen.frame.maxY + display.frame.maxY,
+                    width: rect.width,
+                    height: rect.height
+                )
+
                 guard let image = try? await SCScreenshotManager.captureImage(contentFilter: filter, configuration: config) else {
                     completion(nil)
                     return
                 }
-                completion(self.crop(image, to: rect, display: display))
+                completion(self.crop(image, to: scRect, display: display))
             }
         } else {
             guard let primary = NSScreen.screens.first(where: { $0.frame.origin == .zero }) ?? NSScreen.screens.first else {

Sources/Kapture/ResultWindow.swift

@@ -193,10 +193,14 @@ struct ResultView: View {
             .padding(.top, 10)
 
             if model.mode == .screenshot {
+                GeometryReader { geo in
+                    let imageWidth = CGFloat(model.image.width)
                     Image(nsImage: NSImage(cgImage: model.image, size: .zero))
                         .resizable()
-                    .interpolation(.none)
+                        // Downscale with smoothing (AA); upscale keeps pixels crisp.
+                        .interpolation(imageWidth >= geo.size.width ? .high : .none)
                         .aspectRatio(contentMode: .fit)
+                }
                 .border(Color.secondary.opacity(0.4))
                 .padding(.horizontal, 12)
             } else {

build-app.sh

@@ -108,9 +108,9 @@ cat > "$APP/Contents/Info.plist" <<'PLIST'
     <key>CFBundleIconFile</key>
     <string>Icon</string>
     <key>CFBundleShortVersionString</key>
-    <string>1.1.1</string>
+    <string>1.1.8</string>
     <key>CFBundleVersion</key>
-    <string>11</string>
+    <string>18</string>
     <key>LSUIElement</key>
     <true/>
     <key>NSHighResolutionCapable</key>