Add option to take screenshot

[bryevdv]

@syamajala had asked about a screenshot capability in StanfordLegion/legion#1551 (comment)

This PR adds a screenshot feature to the profiler frontend. Currently it is activated by <ctrl>+Space but open to any alternative suggestions (personally prefer keyboard option to a button, but it would be simple to add one). This approach borrows liberally from the egui plot screenshot example.

Currently just saves the entire window (I think the added context is nice) but image region could be clipped as desired.

cc @manopapad @elliottslaughter

[bryevdv]

This is what all the official egui screenshot examples require 🤷

[bryevdv]

Seems a bit clunky to me, but ref:

/// Request the current frame's pixel data. Needs to be retrieved by calling [`Frame::screenshot`]
/// during [`App::post_rendering`].

[bryevdv]

Currently always defaults to "Untitled" (.png) but we could set a a different default filename if desired

[lightsighter]

Maybe default to the name-of-the-profile.png?

[elliottslaughter]

Or Screenshot_YYYY-MM-DD-HH-MM-SS.png, or something like that.

I agree a more informative default name is helpful.

[bryevdv]

Giver there can be an arbitrary number of source locators I opted for something like @elliottslaughter's datetime suggestion 3be2ff1

I actually wanted Legion Prof 2024-01-11 12:41:27 but annoyingly rfd converts colons to forward slashes 🤷)

[lightsighter]

Currently it is activated by +Space but open to any alternative suggestions (personally prefer keyboard option to a button, but it would be simple to add one).

Is there a reason not to use the print screen key? 😉

[bryevdv]

Is there a reason not to use the print screen key?

There is no print screen key on Mac keyboards, e.g. and also no egui::Key code for print screen that I could see.

[lightsighter]

There is no print screen key on Mac keyboards,

On MAC: print-screen == Ctrl+Cmd+3

also no egui::Key code for print screen that I could see

That's unfortunate.

[bryevdv]

On MAC: print-screen == Ctrl+Cmd+3

Also Shift Command 4, Shift Command 4 + Space, Shift Command 5... We could make any of them work, but I am not sure there is one obvious choice

[elliottslaughter]

Definitely do not overload the Mac print screen keys. They will work fine as long as we don't mess with them.

I assume Seshu is not on a Mac, so what he needs is for this to be available on other platforms.

[bryevdv]

@elliottslaughter CI issues seem to be a version incompat

error: package `cfg-expr v0.15.6` cannot be built because it requires rustc 1.70.0 or newer, while the currently active rustc version is 1.67.1

[bryevdv]

@elliottslaughter any thoughts on the CI issue?

[elliottslaughter]

I bumped the Rust version, can you merge and try again? (Note: please throw away your Cargo.lock changes to avoid downgrading anything by accident.)

[bryevdv]

Unfortunately after merge master (pushed) and regenerating the lockfile, the branch no longer builds for me for any obvious reason at a glance. But I'm about to be OOTO so it will be late next week or the week after before I can get back to look more closely.

[elliottslaughter]

Something you're doing seems to depend on GTK:

The system library `gdk-3.0` required by crate `gdk-sys` was not found.

I'm not sure we want to add additional (non-Rust) dependencies? Is there a way to avoid pulling this in?

[bryevdv]

no idea offhand, this PR just follows the short and simple official egui screenshot example code here GDK is an image library, though, so perhaps the documented screenshot capability relies on it it somehow.

Edit: That isn't the build error I am seeing, though, FWIW (or maybe they are downstream errors, I have not looked into yet)

base ❯ cargo build --all-features
    Updating crates.io index
   Compiling legion_prof_viewer v0.1.0 (/Users/bryan/work/prof-viewer)
error[E0407]: method `post_rendering` is not a member of trait `eframe::App`
    --> src/app.rs:2440:5
     |
2440 | /     fn post_rendering(&mut self, _screen_size_px: [u32; 2], frame: &eframe::Frame) {
2441 | |         // this is inspired by the Egui screenshot example
2442 | |         if let Some(screenshot) = frame.screenshot() {
2443 | |             self.screenshot = Some(screenshot);
2444 | |         }
2445 | |     }
     | |_____^ not a member of trait `eframe::App`

error[E0599]: no method named `screenshot` found for reference `&eframe::Frame` in the current scope
    --> src/app.rs:2442:41
     |
2442 |         if let Some(screenshot) = frame.screenshot() {
     |                                         ^^^^^^^^^^ method not found in `&Frame`

error[E0599]: no method named `request_screenshot` found for mutable reference `&mut eframe::Frame` in the current scope
    --> src/app.rs:2459:19
     |
2459 |             frame.request_screenshot();
     |                   ^^^^^^^^^^^^^^^^^^ method not found in `&mut Frame`