[egui-wgpu] Put the capture module behind a feature flag, make the egui dependency optional (#7698)

This PR enables users of `egui-wgpu` to render `epaint` primitives
without having to bring in the complete `egui` crate and all it's
dependencies.

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/eframe/Cargo.toml

@@ -135,6 +135,7 @@ winit = { workspace = true, default-features = false, features = ["rwh_06"] }
 # optional native:
 egui-wgpu = { workspace = true, optional = true, features = [
   "winit",
+  "capture",
 ] } # if wgpu is used, use it with winit
 pollster = { workspace = true, optional = true } # needed for wgpu
 
@@ -240,7 +241,7 @@ web-sys = { workspace = true, features = [
 ] }
 
 # optional web:
-egui-wgpu = { workspace = true, optional = true } # if wgpu is used, use it without (!) winit
+egui-wgpu = { workspace = true, optional = true, features = ["capture"] } # if wgpu is used, use it without (!) winit
 wgpu = { workspace = true, optional = true }
 
 # Native dev dependencies for testing

crates/egui-wgpu/Cargo.toml

@@ -27,8 +27,11 @@ rustdoc-args = ["--generate-link-to-definition"]
 [features]
 default = ["fragile-send-sync-non-atomic-wasm", "macos-window-resize-jitter-fix", "wgpu/default"]
 
+## Enables the `capture` module for capturing screenshots.
+capture = ["dep:egui"]
+
 ## Enable [`winit`](https://docs.rs/winit) integration. On Linux, requires either `wayland` or `x11`
-winit = ["dep:winit", "winit/rwh_06"]
+winit = ["dep:winit", "winit/rwh_06", "dep:egui", "capture"]
 
 ## Enables Wayland support for winit.
 wayland = ["winit?/wayland"]
@@ -47,7 +50,6 @@ fragile-send-sync-non-atomic-wasm = ["wgpu/fragile-send-sync-non-atomic-wasm"]
 macos-window-resize-jitter-fix = ["wgpu/metal"]
 
 [dependencies]
-egui = { workspace = true, default-features = false }
 epaint = { workspace = true, default-features = false, features = ["bytemuck"] }
 
 ahash.workspace = true
@@ -62,4 +64,5 @@ wgpu = { workspace = true, features = ["wgsl"] }
 
 # Optional dependencies:
 
+egui = { workspace = true, optional = true, default-features = false }
 winit = { workspace = true, optional = true, default-features = false }

crates/egui-wgpu/src/lib.rs

@@ -29,6 +29,7 @@ pub use renderer::*;
 pub use setup::{NativeAdapterSelectorMethod, WgpuSetup, WgpuSetupCreateNew, WgpuSetupExisting};
 
 /// Helpers for capturing screenshots of the UI.
+#[cfg(feature = "capture")]
 pub mod capture;
 
 /// Module for painting [`egui`](https://github.com/emilk/egui) with [`wgpu`] on [`winit`].