LSP Previewer UI Todos

[hunger]

MVP in feature/lsp_preview_ui

• [x] Fix codespaces again... They do not use the WASM preview.
• [x] Decide on the features we want for this: Maybe use preview-api? The description matches nicely :-)
• [x] Make the UI takes the entire available space in WASM mode and have a OK size in native mode.
• [x] Do not panic when ask_editor_to_show_document errors out
• [x] Test that images work properly for every possible combination of LSP and Previewer
  • [x] Fix URL mapping?
• [x] Test to make sure slintpad still works :-)
• [x] Test the native LSP use case in VIM to make sure this does not try to talk to non-existing WASM Previewers which might confuse editors.
• [x] when you close vscode, the LSP no longer quit and the preview window stay visible
• [x] "Restart server" in vscode no longer works

In general

• [x] Add a background of the right color behind the ComponentContainer
  • [x] Use the styles expected background color when displaying a window (#3117)
  • [ ] Show the checkerboard when displaying a random component
• [x] Add a style dropdown into the preview UI
• [x] Allow changing the size of the preview area (by mouse;-)
• [x] Allow setting icon and window title for windows
• [x] Make the UI pretty(er)
• [x] Figure out why the Qt backend fails to bring up the native UI the second time round

[ogoffart]

Add a background of the right color behind the ComponentContainer

This is https://github.com/slint-ui/slint/issues/3117 : the Window doesn't print its own background when used as a child. To fix it we could either:

• ask the compiler to add a Rectangle with the background when use as a child. (But in the case of the ComponentContainer it's not used as a child, so we need an option to the compiler to make it do that anyway)
  • Have the WindowItem actually render a rectangle in its render function. And let the renderer actually skip the root item when rendering (we don't want to do double rendering of the background of the window)

Allow changing the size of the preview area (by mouse;-)

If you want inspiration for Sub window in slint code, have a look at the fancy_demo

https://slintpad.com/preview?load_url=https://raw.githubusercontent.com/slint-ui/slint/master/examples/fancy_demo/main.slint

---

Reply from @hunger:

This is https://github.com/slint-ui/slint/issues/3117 : the Window doesn't print its own background when used as a child.

I edited the text to reflect this.

To fix it we could either: [...]

I was thinking of hacking this by having the ComponentContainer look at its root element. When it can downcast it to a Window element, it can grab the style metrics from the globals and render a rectangle in the background. This may of course not work :-)

[hunger]

Oh, sorry, I did not mean to edit your text:-/

[hunger]

Done and merged!