NSWindow 透明背景 NSCollectionView 背景不重绘

Question

我正在尝试创建一个半透明的 macOS 应用程序。就像 macOS 中包含的终端应用程序一样。我在 Storyboard 中创建了一个透明的 NSWindow 子类和一个非常标准的 NSCollectionView。我可以让应用程序是半透明的，但是当我滚动 NSCollectionViewItems 时，它会使背景完全透明。

问题的代码在这里Github

问题示例

我尝试了很多东西

• 获取NSScroll View的回调，获取UI重绘
• 在 Storyboard 的大多数视图中设置背景
• StackOverflow 问题的建议：StackOverflow

这是自定义 UIWindow

import Cocoa

class MainWindow: NSWindow {

    override init(contentRect: NSRect, styleMask style: NSWindow.StyleMask, backing backingStoreType: NSWindow.BackingStoreType, defer flag: Bool) {
        super.init(contentRect: contentRect, styleMask: style, backing: backingStoreType, defer: false)
        self.backingType = NSWindow.BackingStoreType.buffered
        self.alphaValue = 1.0
        self.backgroundColor = NSColor.clear
        self.isOpaque = false
    }
}

这里是视图控制器

import Cocoa

class ViewController: NSViewController {

    @IBOutlet weak var collectionView: NSCollectionView!
    @IBOutlet weak var scrollView: NSScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()

        configureCollectionView()
        collectionView.register(ReceiverCollectionViewItem.self, forItemWithIdentifier: NSUserInterfaceItemIdentifier(rawValue: "Cell"))
    }

    private func configureCollectionView() {
        let flowLayout = NSCollectionViewFlowLayout()
        flowLayout.itemSize = NSSize(width: 100.0, height: 100.0)
        flowLayout.sectionInset = NSEdgeInsets(top: 10.0, left: 20.0, bottom: 10.0, right: 20.0)
        flowLayout.minimumInteritemSpacing = 20.0
        flowLayout.minimumLineSpacing = 20.0
        collectionView.collectionViewLayout = flowLayout

        scrollView.drawsBackground = false
        scrollView.contentView.drawsBackground = false
        scrollView.backgroundColor = NSColor(calibratedRed: 0.0, green: 0.0, blue: 0.0, alpha: 0.1)

        collectionView.backgroundColors = [NSColor(calibratedRed: 0.0, green: 0.0, blue: 0.0, alpha: 0.1)]
    }
}

extension ViewController: NSCollectionViewDataSource {
    func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10
    }

    func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
        let item = collectionView.makeItem(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "Cell"), for: indexPath) 
        return item
    }
}

Answer 1

经过多次反复试验（更多错误），我找到了解决方案。

在 NSWindow 子类中，如果您设置背景颜色，则会消除背景中清晰的“洞”。

import Cocoa

class MainWindow: NSWindow {

    override init(contentRect: NSRect, styleMask style: NSWindow.StyleMask, backing backingStoreType: NSWindow.BackingStoreType, defer flag: Bool) {
        super.init(contentRect: contentRect, styleMask: style, backing: backingStoreType, defer: false)
        self.backingType = NSWindow.BackingStoreType.buffered
        self.alphaValue = 1.0
        self.backgroundColor = NSColor(calibratedRed: 0.0, green: 0.0, blue: 0.0, alpha: 0.2)
        self.isOpaque = false
    }
}

ViewController 还需要一些东西

import Cocoa

class ViewController: NSViewController {

    @IBOutlet weak var collectionView: NSCollectionView!
    @IBOutlet weak var scrollView: NSScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()

        configureCollectionView()
        collectionView.register(ReceiverCollectionViewItem.self, forItemWithIdentifier: NSUserInterfaceItemIdentifier(rawValue: "Cell"))
    }

    private func configureCollectionView() {
        let flowLayout = NSCollectionViewFlowLayout()
        flowLayout.itemSize = NSSize(width: 100.0, height: 100.0)
        flowLayout.sectionInset = NSEdgeInsets(top: 10.0, left: 20.0, bottom: 10.0, right: 20.0)
        flowLayout.minimumInteritemSpacing = 20.0
        flowLayout.minimumLineSpacing = 20.0
        collectionView.collectionViewLayout = flowLayout

        scrollView.drawsBackground = false
        scrollView.contentView.drawsBackground = false
        scrollView.backgroundColor = NSColor.clear

        collectionView.backgroundColors = [.clear]
    }
}

extension ViewController: NSCollectionViewDataSource {
    func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10
    }

    func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
        let item = collectionView.makeItem(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "Cell"), for: indexPath) 
        return item
    }
}