Central GpuReadback handling for re_viewer, experimental space view screenshots

[Wumpf]

Screen.Recording.2023-03-27.at.15.27.07.mov

Created the embryo of handling readback data in a generalized & robust fashion across the viewer. Using this to implement screenshot functionality on 2d/3d space views - since it's limited to those & doesn't include egui rendered labels, I put this behind a feature flag.
Note that this is force-disabled on the Web.

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)

[teh-cmc]

Can't run api_demo_rs anymore:

cargo r -p api_demo
   Compiling re_web_viewer_server v0.3.1 (/home/cmc/dev/rerun-io/rerun/crates/re_web_viewer_server)
   Compiling re_viewer v0.3.1 (/home/cmc/dev/rerun-io/rerun/crates/re_viewer)
error: failed to run custom build command for `re_web_viewer_server v0.3.1 (/home/cmc/dev/rerun-io/rerun/crates/re_web_viewer_server)`

Caused by:
  process didn't exit successfully: `/home/cmc/dev/rerun-io/rerun/target/debug/build/re_web_viewer_server-d699cc4c852e2d39/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-changed=../../web_viewer/index.html
  cargo:rerun-if-changed=../../web_viewer/sw.js
  cargo:rerun-if-changed=/home/cmc/dev/rerun-io/rerun/crates/re_viewer/Cargo.toml
  cargo:rerun-if-changed=/home/cmc/dev/rerun-io/rerun/crates/re_viewer/build.rs
  [...]

  --- stderr
  Building web viewer wasm…
  We assume you've already run ./scripts/setup_web.sh
  Compiling rust to wasm in /home/cmc/dev/rerun-io/rerun/target_wasm…
  > "cargo" "build" "--package" "re_viewer" "--lib" "--target" "wasm32-unknown-unknown" "--target-dir" "/home/cmc/dev/rerun-io/rerun/target_wasm"
     Compiling re_viewer v0.3.1 (/home/cmc/dev/rerun-io/rerun/crates/re_viewer)
  error[E0433]: failed to resolve: could not find `Clipboard` in `misc`
     --> crates/re_viewer/src/ui/viewport.rs:576:22
      |
  576 |         crate::misc::Clipboard::with(|clipboard| {
      |                      ^^^^^^^^^ could not find `Clipboard` in `misc`
      |
  help: consider importing this struct
      |
  5   | use web_sys::Clipboard;
      |
  help: if you import `Clipboard`, refer to it directly
      |
  576 -         crate::misc::Clipboard::with(|clipboard| {
  576 +         Clipboard::with(|clipboard| {
      |

  For more information about this error, try `rustc --explain E0433`.
  error: could not compile `re_viewer` due to previous error
  thread 'main' panicked at 'Failed to build Wasm', crates/re_build_web_viewer/src/lib.rs:88:5
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[teh-cmc]

Can confirm the screenshots are successfully taken and save to disk on Linux, both x11 and Wayland.

The copy-to-clipboard thing only works when using the x11 backend though; I think that's because we're trying to use the x11 clipboard APIs even when running on the Wayland backend:

[2023-03-28T06:44:38Z INFO  re_viewer::misc::clipboard] Image copied to clipboard
[2023-03-28T06:44:38Z INFO  re_viewer::ui::viewport] Saved screenshot to "/home/cmc/dev/rerun-io/rerun/Screenshot segdemo - 1.png" and copied to clipboard.
[2023-03-28T06:44:47Z WARN  arboard::platform::linux::x11] Could not hand the clipboard contents over to the clipboard manager. The request timed out.

Note the arboard::platform::linux::x11 above, even though I'm actually running through Wayland!

[teh-cmc]

Pleasantly straightforward 👍

I personally wouldn't mind an extra option to disable saving to disk, I hate having stuff getting written to my disk 😬

[Wumpf]

strange, api demo compiles just fine for me!

[Wumpf]

ah I think you haven't been on the latest commit where I fixed web build?

[Wumpf]

Just for you @teh-cmc ;)

(yes the ui looks ugly, don't care atm, it's experimental anyways)