WKWebView CALayer 到图像导出空白图像

Question

我正在尝试对网页进行屏幕截图，但图像始终为空白（白色）。

我正在使用此代码将 CALayer 转换为 Data

extension CALayer {

/// Get `Data` representation of the layer.
///
/// - Parameters:
///   - fileType: The format of file. Defaults to PNG.
///   - properties: A dictionary that contains key-value pairs specifying image properties.
///
/// - Returns: `Data` for image.

func data(using fileType: NSBitmapImageFileType = .PNG, properties: [String : Any] = [:]) -> Data {
    let width = Int(bounds.width * self.contentsScale)
    let height = Int(bounds.height * self.contentsScale)
    let imageRepresentation = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: width, pixelsHigh: height, bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: NSDeviceRGBColorSpace, bytesPerRow: 0, bitsPerPixel: 0)!
    imageRepresentation.size = bounds.size

    let context = NSGraphicsContext(bitmapImageRep: imageRepresentation)!

    render(in: context.cgContext)

    return imageRepresentation.representation(using: fileType, properties: properties)!
}

}

然后将数据写入文件 .png

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) 
{
    let d = web.layer?.data() as NSData?  //web is the instance of WKWebView
    d!.write(toFile: "/Users/mac/Desktop/web.png", atomically: true)
}

但我得到的是空白（白色）png 而不是我所期望的

1).我做错了什么？

2).是否有任何其他可能的方法来获取图像表示网页(使用swift)?

谢谢！

Answer 1

最新更新：

现在您可以像 WebView 一样对 WKWebView 进行截图了。

Apple added new method 对于 iOS 和 macOS，

func takeSnapshot(with snapshotConfiguration: WKSnapshotConfiguration?, 
completionHandler: @escaping (NSImage?, Error?) -> Void)

但它仍处于测试阶段。

您无法截取 WKWebView 的屏幕截图。它总是 returns 空白图像。即使您尝试将 WKWebView 包含在另一个 NSView 中并截取屏幕截图，它也会给您空白图像代替 WKWebView.

您应该使用 WebView 而不是 WKWebView 来达到您的目的。检查这个 .

如果您可以使用私有框架（苹果不允许您的应用程序出现在其商店中），请检查此 GitHub。它是用 Obj-C 编写的。我不知道 Obj-C，所以我无法解释该代码中发生的事情。但它声称可以完成这项工作。

您最好的方法是使用 WebView 并在 WebView 上使用您提到的扩展程序 data()。

只是一个问题：你为什么不使用 phantomJS？

PS。这么晚才回复很抱歉。我没有看到你的电子邮件。

Answer 2

更新：Swift 5 添加到先前。

我不想在输出中进行控制，所以我给它绑定了一个键序列（本地键监视器）：

case [NSEvent.ModifierFlags.option, NSEvent.ModifierFlags.command]:
    guard let window = NSApp.keyWindow, let wvc = window.contentViewController as? WebViewController else {
        NSSound(named: "Sosumi")?.play()
        return true
    }
    wvc.snapshot(self)
    return true

并在沙盒环境中工作。我们在默认设置中保留了一堆用户设置，比如他们希望捕获快照的位置 (~/Desktop)，所以第一次我们 ask/authenticate，缓存它，随后调用的应用程序委托将恢复沙箱书签（ s).

var webImageView = NSImageView.init()
var player: AVAudioPlayer?

@IBAction func snapshot(_ sender: Any) {
    webView.takeSnapshot(with: nil) {image, error in
        if let image = image {
            self.webImageView.image = image
        } else {
            print("Failed taking snapshot: \(error?.localizedDescription ?? "--")")
            self.webImageView.image = nil
        }
    }
    guard let image = webImageView.image else { return }
    guard let tiffData = image.tiffRepresentation else { NSSound(named: "Sosumi")?.play(); return }

    //  1st around authenticate and cache sandbox data if needed
    if appDelegate.isSandboxed(), appDelegate.desktopData == nil {
        let openPanel = NSOpenPanel()
        openPanel.message = "Authorize access to Desktop"
        openPanel.prompt = "Authorize"
        openPanel.canChooseFiles = false
        openPanel.canChooseDirectories = true
        openPanel.canCreateDirectories = false
        openPanel.directoryURL = appDelegate.getDesktopDirectory()
        openPanel.begin() { (result) -> Void in
            if (result == NSApplication.ModalResponse.OK) {
                let desktop = openPanel.url!
                _ = self.appDelegate.storeBookmark(url: desktop, options: self.appDelegate.rwOptions)
                self.appDelegate.desktopData = self.appDelegate.bookmarks[desktop]
                UserSettings.SnapshotsURL.value = desktop.absoluteString
            }
        }
    }

    //  Form a filename: ~/"<app's name> View Shot <timestamp>"
    let dateFMT = DateFormatter()
    dateFMT.dateFormat = "yyyy-dd-MM"
    let timeFMT = DateFormatter()
    timeFMT.dateFormat = "h.mm.ss a"
    let now = Date()

    let path = URL.init(fileURLWithPath: UserSettings.SnapshotsURL.value).appendingPathComponent(
        String(format: "%@ View Shot %@ at %@.png", appDelegate.appName, dateFMT.string(from: now), timeFMT.string(from: now)))

    let bitmapImageRep = NSBitmapImageRep(data: tiffData)

    //  With sandbox clearance to the desktop...
    do
    {
        try bitmapImageRep?.representation(using: .png, properties: [:])?.write(to: path)

        // https://developer.apple.com/library/archive/qa/qa1913/_index.html
        if let asset = NSDataAsset(name:"Grab") {

            do {
                // Use NSDataAsset's data property to access the audio file stored in Sound.
                 player = try AVAudioPlayer(data:asset.data, fileTypeHint:"caf")
                // Play the above sound file.
                player?.play()
            } catch {
                Swift.print("no sound for you")
            }
        }
    } catch let error {
        NSApp.presentError(error)
        NSSound(named: "Sosumi")?.play()
    }
}

WKWebView CALayer 到图像导出空白图像

WKWebView CALayer to image exports blank image

macos

cocoa

swift

wkwebview