core: Implement TextField control characters

[JMcKiern]

This pr implements some control character handling for text fields (eg CtrlC, CtrlV).

I'm submitting this as a draft to make sure that I'm going about this the right way.

TODO

• - Up, Down - Should move caret between lines
• - Home, End - Should go to the start/end of the line
• - Ctrl+Left, Ctrl+Right - Should go to the start/end of the previous/next word

[Herschel]

I was thinking maybe we should add a separate enum to handle keyboard control/navigation commands, i.e. something like PlayerEvent::TextControl that would have MoveLeft, SelectAll, Copy, PageUp, etc., and this could be handled by a separate method on the textfield. This way these commands are explicit, as opposed to being dumped into the ASCII control characters (e.g. on Mac, where Cmd+C is different from Ctrl+C, Ctrl+Ins for copy on Windows).

[JMcKiern]

Hey, sorry for the wait. I've added the TextControl event, a TextControlCode enum and implemented SelectAll, Copy, Paste and Cut.

I couldn't figure out how to check if Ruffle is running on MacOS on web so I've just left this as a TODO.

Also, should I move the following to this TextControl implementation?

• Backspace and Delete - currently handled in text_input()
• Left and Right - currently handled in handle_clip_event()

[Herschel]

Yes, I'd say lets try to get all of the navigation and control commands into one code path.
For Copy/Paste on Web, I wonder if it should hook into https://developer.mozilla.org/en-US/docs/Web/API/Element/copy_event instead of explicitly looking for keys.

[JMcKiern]

I've moved Delete and Backspace to text_control_input() but I just want to note here that I need to look into the onKeyDown and similar listeners. For example, it fires for Backspace but not for Ctrl+C.

For those copy events, it looks like we'd need to enable the unstable apis in web_sys: https://rustwasm.github.io/wasm-bindgen/api/web_sys/struct.ClipboardEvent.html

[Herschel]

I think enabling the unstable APIs is fine (we are somewhat on the bleeding edge of things, so we can deal with APIs breaking from time to time).

[Txori]

Hello, you forgot to add Page Up and Page Down to the TODO list :)

[allancoding]

Is there any update on progress?

[n0samu]

I updated and finished this PR in #11059. Thanks so much for your work on this!