WkWebView.txt

Installed Safari:
Version 11.0.1 (13604.3.5)

using private safari framework:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_1) AppleWebKit/604.3.5 (KHTML, like Gecko)

----

http://nshipster.com/wkwebkit/

----

https://stackoverflow.com/questions/31969950/wkwebview-cachedisplayinrect-screenshot-in-os-x

I try to make a screenshot of WKWebView is OS X app and get completely empty screenshot. This code works fine with original WebView but does not works with WKWebView.

NSView *view = webView;
NSRect bounds = [view bounds];

NSBitmapImageRep *bitmapdata = [view bitmapImageRepForCachingDisplayInRect: bounds];
[webView cacheDisplayInRect: bounds toBitmapImageRep: bitmapdata];
Any ideas how to fix?

----

Now you can take the screenshot using WKWebView.

Apple added a new method,

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

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

But its still in Beta.

----

https://stackoverflow.com/questions/46842384/wkwebkit-takesnapshotwith-snapshotconfiguration-not-working-on-ios-device

http://www.openradar.me/33812691
iOS 11 takeSnapshot method on WKWebView not usable

Originator:	Josh.Lieberman92	
Number:	rdar://33812691	Date Originated:	August 9 2017
Status:	Open	Resolved:	
Product:	iOS + SDK	Product Version:	Xcode 9 beta 5
Classification:	Serios Bug	Reproducible:	Always
 
Area:
WebKit

Summary:
Because the header WKSnapshotConfiguration.h is not public, the method

takeSnapshot(with snapshotConfiguration: WKSnapshotConfiguration?, completionHandler: @escaping (UIImage?, Error?) -> Swift.Void)

is not visible on an instance of WKWebView.

Steps to Reproduce:
Try to use takeSnapshot(with snapshotConfiguration: WKSnapshotConfiguration?, completionHandler: @escaping (UIImage?, Error?) -> Swift.Void) in a Swift project.

Observe the method is not visible to the compiler.

Expected Results:
The method should be usable in the latest Xcode 9 beta.

Observed Results:
The method is not usable in the latest Xcode 9 beta.

Version:
Xcode 9 beta 5

----

Add #import <WebKit/WKSnapshotConfiguration.h> to your bridging header.

https://stackoverflow.com/q/45600451/2415822

----

https://bugs.webkit.org/show_bug.cgi?id=161450

Bug 161450
Summary: [Cocoa] No reliable way to get a snapshot of WKWebView

The cocoa API -[NSView cacheDisplayInRect:(NSRect)rect
toBitmapImageRep:(NSBitmapImageRep *)bitmapImageRep] does not work for
WKWebView, it only returns an empty image. We need a way to get the
visible contents of the web page on macOS. The UI is rendered in a
separate process, there should be an API to grab the visible bitmap
from the UI process and expose it as a method on WKWebView that the
embedding application can consume. We need to be able to grab the web
page contents regardless if the WKWebView is hidden or overlapped by
other views, CGWindowListCreateImage will not work for that scenario.

For iOS, you can use the -[UIView drawViewHierarchyInRect:(CGRect)rect
afterScreenUpdates:(BOOL)afterUpdates] API to get the web page
contents.

...

This is a software painted snapshot, meaning that 3D transforms will
be flattened and ugly, and video/WebGL may-or-may-not work. So, it's
not great.

We have code (WebViewImpl::takeViewSnapshot) that shows how to do a
window-server snapshot, which captures all of those things, but it has
a downside: if the web view is obscured, the thing it's obscured will
will end up in the snapshot as well.

_snapshotRect:intoImageOfWidth:completionHandler: gets around this,
but uses functions that are only available/possible on iOS. We should
definitely make use of that to implement this method on iOS, though,
since it is much, much better than a software snapshot.

...

Thanks for taking a look Darin. I have searched for solutions using
AppKit API, and it looks like other developers are having the same
issue where none of the AppKit API will capture the contents of
WKWebView. Many people refer to a private API solution, which is no
good for store apps. With iOS UIKit, we are able to get the contents
with (- (BOOL)drawViewHierarchyInRect:(CGRect)rect
afterScreenUpdates:(BOOL)afterUpdates), but a solution does not seem
to be available for Mac. The reason I was adding the API was for Mac,
but to be consistent and allow for developer code reuse I am making it
available for both Mac and iOS. If you know of a different method that
I did not try, please let me know. Below are some examples I have
tried and verified they cannot get the WKWebView snapshot on OSX,
while most of them work on the legacy WebVew.


- (NSImage *)snapshotView1:(NSView *)view
{
    // WebView returns the correct content, WKWebView returns white snapshot.
    NSImage *image = [[NSImage alloc] initWithSize:view.bounds.size];
    NSBitmapImageRep *imageRep = [view bitmapImageRepForCachingDisplayInRect:view.bounds];
    [view cacheDisplayInRect:view.bounds toBitmapImageRep:imageRep];
    [image addRepresentation:imageRep];

    return image;
}


- (NSImage *)snapshotView2:(NSView *)view
{
    // WebView returns the correct content, WKWebView returns white snapshot.
    NSImage *image = [[NSImage alloc] initWithSize:view.bounds.size];
    [image lockFocus];
    CGContextRef ctx = [NSGraphicsContext currentContext].graphicsPort;
    [view.layer renderInContext:ctx];
    [image unlockFocus];
    
    return image;

}

- (NSImage *)snapshotView3:(NSView *)view
{
    // Returns an empty image with both WKWebView and WebView.
    [view lockFocus];
    NSImage *image = [[NSImage alloc] initWithData:[view dataWithPDFInsideRect:view.bounds]];
    [view unlockFocus];
    
    return image;
    
}

- (CGImageRef)snapshotView4:(NSView *)view
{
    // CGWindowListCreateImage can get WKWebView content, but only the visible portions in the parented window. If the view is inside a scrollview, clipped by the window, or overlapped with another view, it cannot access the full WKWebView viewport.
    CGImageRef image = CGWindowListCreateImage(CGRectNull, kCGWindowListOptionIncludingWindow, (CGWindowID)self.view.window.windowNumber, kCGWindowImageDefault);

    return image;
}

----

https://forums.developer.apple.com/message/117074#117074

umigliore
Feb 22, 2016 8:54 AM
(in response to chinrock)
It works with a delay :
 
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    [self performSelector:@selector(snapshot:) withObject:webView afterDelay:0.1];
}
 
... and first form of screenshot, i.e. not using snapshotViewAfterScreenUpdates
 
- (UIImage *)snapshot:(UIView *)view  
{  
  UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0);  
  [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];  
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();  
  UIGraphicsEndImageContext();    
  return image;  
}

----

https://github.com/lemonmojo/WKWebView-Screenshot

https://developer.apple.com/documentation/webkit/wkwebview/2873260-takesnapshotwithconfiguration

https://bugs.webkit.org/show_bug.cgi?id=161450

https://github.com/WebKit/webkit/blob/c637754ee7dfca6142e441d2040026903fee0c1f/Source/WebKit/UIProcess/API/Cocoa/WKSnapshotConfiguration.h
https://github.com/WebKit/webkit/blob/c637754ee7dfca6142e441d2040026903fee0c1f/Source/WebKit/UIProcess/API/Cocoa/WKSnapshotConfiguration.mm
https://github.com/WebKit/webkit/blob/5e250ba19a76ccf164d1d31e6a49700bab34826e/Tools/TestWebKitAPI/Tests/WebKitCocoa/WKWebViewSnapshot.mm