Bug 220197 – WKWebView inside a fullscreen quicklook preview lag while page scrolling

• Status: NEW
• Component: WebKit2

I have a Quicklook appex that show the file contents by a WKWebView. 
The preview inside a normal quicklook window works well, but if the window is in fullscreen is not possibile to scroll with the trackpad gesture.

I do not know is is related to bug [219632](https://bugs.webkit.org/show_bug.cgi?id=219632).
Using the deprecated WebView insted of WKWebView the preview can be scrolled on fullscreen mode.

I have created a demo code here:
https://github.com/sbarex/QLTest

Also, non in full screen, if I click on a link to a local anchor, the scroll start after some delay.

[Radar WebKit Bug Importer]

<rdar://problem/72817636>

[Simon Fraser (smfr)]

The subject says "preview lag" but you also say "is not possibile to scroll". "Lag" implies that it scrolls, but slowly. Could you clarify?

In full screen mode, the two-finger gesture on the trackpad does not scroll the content. But executing the gesuture quickly (which in normal situation would make the content scroll fast) you can scroll about 2 lines at a time, jerky and without the elastic effect.

[Simon Fraser (smfr)]

Please give instructions about how to use your test project to get fullscreen QuickLook. Should I run the QLTest target and choose "Open QuickLook for a test file"?

What macOS version are you testing on? Does the bug only occur on some OS versions?

(In reply to Simon Fraser (smfr) from comment #5)
> Please give instructions about how to use your test project to get
> fullscreen QuickLook. Should I run the QLTest target and choose "Open
> QuickLook for a test file"?
> 
> What macOS version are you testing on? Does the bug only occur on some OS
> versions?

You must open the quicklook preview from the finder (open from the app do not show the fullscreen button!). 
Follow these steps:
- download the precompiled test app from https://github.com/sbarex/QLTest/releases
- move the app on the Applications folder (this force the detection of the ql extension)
- launch the app and push on the button "browse for a test file" to select a test file on the finder. 
- From the selected file on Finder open the quicklook preview.
- Maximize the preview to fullscreen.

I'm using Big Sur 11.1 (Intel). On Catalina I do not detect this bug.