Add egui_glow as an opt-in backend to eframe (#817)

* Make egui_glow and opt-in backend for eframe

* Add egui_glow to Cargo.toml and to CI

* Reference egui_glow where egui_glium is mentioned

* Remove path-patches from root Cargo.toml

* Add instructions on how to enable the glow backend of eframe

eframe/CHANGELOG.md

@@ -1,7 +1,7 @@
 # Changelog for eframe
 All notable changes to the `eframe` and `epi` crates.
 
-NOTE: [`egui_web`](egui_web/CHANGELOG.md), [`egui-winit`](egui-winit/CHANGELOG.md) and [`egui_glium`](egui_glium/CHANGELOG.md) have their own changelogs!
+NOTE: [`egui_web`](egui_web/CHANGELOG.md), [`egui-winit`](egui-winit/CHANGELOG.md), [`egui_glium`](egui_glium/CHANGELOG.md), and [`egui_glow`](egui_glow/CHANGELOG.md) have their own changelogs!
 
 
 ## Unreleased
@@ -9,7 +9,7 @@ NOTE: [`egui_web`](egui_web/CHANGELOG.md), [`egui-winit`](egui-winit/CHANGELOG.m
 * Remove "http" feature (use https://github.com/emilk/ehttp instead!).
 * Increase native scroll speed.
 * Add `App::persist_native_window` and `App::persist_egui_memory` to control what gets persisted.
-* Add new backend `egui_glow` as an alternative to `egui_glium` (not yet exposed as a feature flag)
+* Add new backend `egui_glow` as an alternative to `egui_glium`. Enable with `default-features = false, features = ["default_fonts", "egui_glow"]`.
 
 
 ## 0.14.0 - 2021-08-24

eframe/Cargo.toml

@@ -28,7 +28,8 @@ epi = { version = "0.14.0", path = "../epi" }
 
 # For compiling natively:
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-egui_glium = { version = "0.14.0", path = "../egui_glium", default-features = false, features = ["clipboard", "links"] }
+egui_glium = { version = "0.14.0", path = "../egui_glium", default-features = false, features = ["clipboard", "links"], optional = true }
+egui_glow = { version = "0.14.0", path = "../egui_glow", default-features = false, features = ["clipboard", "links"], optional = true }
 
 # For compiling to web:
 [target.'cfg(target_arch = "wasm32")'.dependencies]
@@ -39,7 +40,7 @@ image = { version = "0.23", default-features = false, features = ["png"] }
 rfd = "0.5.0"
 
 [features]
-default = ["default_fonts"]
+default = ["default_fonts", "egui_glium"]
 
 # If set, egui will use `include_bytes!` to bundle some fonts.
 # If you plan on specifying your own fonts you may disable this feature.

eframe/README.md

@@ -14,7 +14,7 @@ To get started, go to <https://github.com/emilk/eframe_template/> and follow the
 
 `eframe` is a very thin crate that re-exports [`egui`](https://github.com/emilk/egui) and[`epi`](https://github.com/emilk/egui/tree/master/epi) with thin wrappers over the backends.
 
-`eframe` uses [`egui_web`](https://crates.io/crates/egui_web) and [`egui_glium`](https://crates.io/crates/egui_glium).
+`eframe` uses [`egui_web`](https://github.com/emilk/egui/tree/master/egui_web) for web and [`egui_glium`](https://github.com/emilk/egui/tree/master/egui_glium) or [`egui_glow`](https://github.com/emilk/egui/tree/master/egui_glow) for native.
 
 To use on Linux, first run:
 
@@ -24,6 +24,12 @@ sudo apt-get install libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev lib
 
 
 ## Alternatives
+The default native backend for `eframe` is currently [`egui_glium`](https://github.com/emilk/egui/tree/master/egui_glium), but you can try out the new [`egui_glow`](https://github.com/emilk/egui/tree/master/egui_glow) backend by putting this in your `Cargo.toml`:
+
+``` toml
+eframe = { version = "*", default-features = false, features = ["default_fonts", "egui_glow"] }
+```
+
 `eframe` is not the only way to write an app using `egui`! You can also try [`egui-miniquad`](https://github.com/not-fl3/egui-miniquad) and [`egui_sdl2_gl`](https://github.com/ArjunNair/egui_sdl2_gl).
 
 

eframe/src/lib.rs

@@ -9,7 +9,8 @@
 //! You write your application code for [`epi`] (implementing [`epi::App`]) and then
 //! call from [`crate::run_native`] your `main.rs`, and/or call `eframe::start_web` from your `lib.rs`.
 //!
-//! `eframe` is implemented using [`egui_web`](https://docs.rs/egui_web) and [`egui_glium`](https://docs.rs/egui_glium).
+//! `eframe` is implemented using [`egui_web`](https://github.com/emilk/egui/tree/master/egui_web) for web and
+//! [`egui_glium`](https://github.com/emilk/egui/tree/master/egui_glium) or [`egui_glow`](https://github.com/emilk/egui/tree/master/egui_glow) for native.
 
 // Forbid warnings in release builds:
 #![cfg_attr(not(debug_assertions), deny(warnings))]
@@ -61,6 +62,22 @@ pub fn start_web(canvas_id: &str, app: Box<dyn epi::App>) -> Result<(), wasm_bin
 
 /// Call from `fn main` like this: `eframe::run_native(Box::new(MyEguiApp::default()))`
 #[cfg(not(target_arch = "wasm32"))]
+#[cfg(feature = "egui_glium")]
 pub fn run_native(app: Box<dyn epi::App>, native_options: epi::NativeOptions) -> ! {
     egui_glium::run(app, &native_options)
 }
+
+/// Call from `fn main` like this: `eframe::run_native(Box::new(MyEguiApp::default()))`
+#[cfg(not(target_arch = "wasm32"))]
+#[cfg(not(feature = "egui_glium"))] // make sure we still compile with `--all-features`
+#[cfg(feature = "egui_glow")]
+pub fn run_native(app: Box<dyn epi::App>, native_options: epi::NativeOptions) -> ! {
+    egui_glow::run(app, &native_options)
+}
+
+// disabled since we want to be able to compile with `--all-features`
+// #[cfg(all(feature = "egui_glium", feature = "egui_glow"))]
+// compile_error!("Enable either egui_glium or egui_glow, not both");
+
+#[cfg(all(not(feature = "egui_glium"), not(feature = "egui_glow")))]
+compile_error!("Enable either egui_glium or egui_glow");