[WinUI3] Support continuous mouse event from web content to the native window

[d2phap]

Is your feature request related to a problem? Please describe.
I create a small webapp that allows dragging to arrange the shapes (https://d2phap.github.io/shape-arrangement/), and I want to bring this to Webview2. However, the mouse event is not captured when I move the cursor out of the Webview2
Steps:

• Click and hold on a shape
• Still hold and drag the shape
• Move cursor out of the window (or the Webview2)
• The shape is not followed the cursor anymore

Describe the solution you'd like and alternatives you've considered

• There should be an API / option to allow the cursor continue to capture out of the webview2
• This will remove the gap of native app and webview2 app

AB#33613498

[champnic]

Thanks for the feature request @d2phap! I've added it as a scenario on our backlog. I believe this may be possible in Win32 because you'll have more control over sending the mouse messages to the WebView2 HWND. For the other cases (WPF, Winforms, WinUI) I'm not sure it would even be possible, as mouse capture is mostly controlled by those frameworks. But we'll investigate and see if there's a way to do this. Thanks!

[d2phap]

Thanks @champnic
As I tried this with Electronjs, I could pan the web content out of the window. I hope Webview2 also support it.

[d2phap]

More information, the JavaScript API Element.setPointerCapture() allows to do this in browser, I can drag and pan the element when my mouse is out of the browser window, but this does not work with Webview2.

Example and Demo: https://developer.mozilla.org/en-US/docs/Web/API/Element/setPointerCapture#example

[champnic]

Does this work for you in the browser (Chrome or Edge) if you drag your mouse outside of the window bounds?

[d2phap]

Yea, it works in all browsers, but Webview2.
I haven't tried this in another Webview lib (CEFSharp,...)

[champnic]

Thanks for confirming!

[d2phap]

JFYI
Today I try using Webview2 in WPF, and it works. Apparently, the issue happens with WinUI3 window.