Webview Api Prototype

[mjbvz]

Moving #41853 to branch on main repo

---

Proposes a new Api for webviews. This API aims to make the current html preview api more usable, safer, and more extensible for the future.

Besides the new API, the new webviews also differ in several important ways:

• They are no longer loaded in the file:// origin so they can't read files on disk (you have to use the new protocols for this)
• Scripts are disabled by default
• Command uris are disabled by default
• postMessage inside of webviews now posts back to vscode directly (no more weird click faking required)

TODO

• Discuss and finalize API
• Add onFocus and onBlur to the webview object
• See if implementation can be cleaned up
• Add dispose method on webview
• Add editorColumn property on webview
• Make enableCommandUris option actually enable command uris
• Add a new protocol for accessing a resource inside of a workspace folder (markdown loading a local image for example)
• Finish moving markdown extension to use the new API

[mike-lischke]

A suggestion: allow reading the current content of the view as text. This way it's possible to see the actual HTML text, including what vscode added/changed (and store it on disk, for further use). And I would love to see a way to access variables in the DOM. That doesn't require to make the entire DOM public, just a way to read and set variables. This would make updating a webview a lot simpler, without fully reloading it. It would also allow to save and restore state, in case such a view must be generated the same way as it was when the user left it.

[mjbvz]

@mike-lischke This new API makes it easier to implement that functionality if you would find it useful. They are a bit too high level in my view for the vscode core api

[mike-lischke]

Thanks @mjbvz, I'll certainly give it a try. The simplified messaging looks good, I can probably come up with a function that allows to update variables via that. Does keepAlive keep the content also if the webview's tab is closed or only when it becomes inactive (switching to another tab). For me it is enough keep the content as long as the tab exists, not longer.

[mike-lischke]

@mjbvz Will you add a WebView example to https://github.com/Microsoft/vscode-extension-samples?

[chongchai]

@mjbvz when the WebView can be used in the extension development?
I can't wait to use it.