egui_web: always use the glow painter, and remove the old WebGL code. (#1356)

* egui_web: always use the glow painter, and remove the old WebGL code.
* Clean up the WebPainter trait
* Clarify WebGL1 warning text in color test

The glow painter became standard in egui 0.17, and I've heard no complaints! So let's simplify and go all in on glow.

Part of #1198

Author: emilk

eframe/Cargo.toml

@@ -59,9 +59,7 @@ egui-winit = { version = "0.17.0", path = "../egui-winit", default-features = fa
 
 # web:
 [target.'cfg(target_arch = "wasm32")'.dependencies]
-egui_web = { version = "0.17.0", path = "../egui_web", default-features = false, features = [
-  "glow",
-] }
+egui_web = { version = "0.17.0", path = "../egui_web", default-features = false }
 
 
 [dev-dependencies]

egui_demo_lib/src/apps/color_test.rs

@@ -38,7 +38,7 @@ impl epi::App for ColorTest {
         egui::CentralPanel::default().show(ctx, |ui| {
             if frame.is_web() {
                 ui.label(
-                    "NOTE: The WebGL1 backend without sRGB support does NOT pass the color test.",
+                    "NOTE: Some old browsers stuck on WebGL1 without sRGB support will not pass the color test.",
                 );
                 ui.separator();
             }

egui_demo_lib/src/backend_panel.rs

@@ -274,9 +274,6 @@ fn show_integration_name(ui: &mut egui::Ui, integration_info: &epi::IntegrationI
                     format!("https://github.com/emilk/egui/tree/master/{}", name),
                 );
             }
-            name if name.starts_with("egui_web") => {
-                ui.hyperlink_to(name, "https://github.com/emilk/egui/tree/master/egui_web");
-            }
             name => {
                 ui.label(name);
             }

egui_web/CHANGELOG.md

@@ -4,6 +4,7 @@ All notable changes to the `egui_web` integration will be noted in this file.
 
 ## Unreleased
 * egui code will no longer be called after panic ([#1306](https://github.com/emilk/egui/pull/1306))
+* Remove the "webgl" feature. `egui_web` now always use `glow` (which in turn wraps WebGL) ([#1356](https://github.com/emilk/egui/pull/1356)).
 
 
 ## 0.17.0 - 2022-02-22

egui_web/Cargo.toml

@@ -27,18 +27,12 @@ crate-type = ["cdylib", "rlib"]
 
 
 [features]
-default = ["default_fonts", "glow"]
+default = ["default_fonts"]
 
 # If set, egui will use `include_bytes!` to bundle some fonts.
 # If you plan on specifying your own fonts you may disable this feature.
 default_fonts = ["egui/default_fonts"]
 
-# Use glow as the renderer.
-glow = ["egui_glow", "egui_glow/epi"]
-
-# Alternative to the glow renderer.
-webgl = []
-
 # enable persisting egui memory
 persistence = ["egui/persistence", "ron", "serde"]
 
@@ -52,7 +46,7 @@ egui = { version = "0.17.0", path = "../egui", default-features = false, feature
   "single_threaded",
   "tracing",
 ] }
-egui_glow = { version = "0.17.0", path = "../egui_glow", optional = true, default-features = false }
+egui_glow = { version = "0.17.0", path = "../egui_glow", default-features = false }
 epi = { version = "0.17.0", path = "../epi" }
 
 bytemuck = "1.7"
@@ -106,15 +100,8 @@ features = [
   "TouchEvent",
   "TouchList",
   "WebGl2RenderingContext",
-  "WebGlBuffer",
   "WebglDebugRendererInfo",
-  "WebGlFramebuffer",
-  "WebGlProgram",
   "WebGlRenderingContext",
-  "WebGlShader",
-  "WebGlTexture",
-  "WebGlUniformLocation",
-  "WebGlVertexArrayObject",
   "WheelEvent",
   "Window",
 ]

egui_web/README.md

@@ -14,7 +14,7 @@ Check out [eframe_template](https://github.com/emilk/eframe_template) for an exa
 
 ## Downsides with using egui on the web
 
-`egui_web` uses WebGL and WASM, and almost nothing else from the web tech stack. This has some benefits, but also produces some challanges and serious downsides.
+`egui_web` uses WebGL (via [`glow`](https://crates.io/crates/glow)) and WASM, and almost nothing else from the web tech stack. This has some benefits, but also produces some challanges and serious downsides.
 
 * Rendering: Getting pixel-perfect rendering right on the web is very difficult.
 * Search: you cannot search an egui web page like you would a normal web page.

egui_web/src/backend.rs

@@ -5,25 +5,10 @@ pub use egui::{pos2, Color32};
 
 // ----------------------------------------------------------------------------
 
-fn create_painter(canvas_id: &str) -> Result<Box<dyn Painter>, JsValue> {
-    // Glow takes precedence:
-    #[cfg(all(feature = "glow"))]
-    return Ok(Box::new(
+fn create_painter(canvas_id: &str) -> Result<Box<dyn WebPainter>, JsValue> {
+    Ok(Box::new(
         crate::glow_wrapping::WrappedGlowPainter::new(canvas_id).map_err(JsValue::from)?,
-    ));
-
-    #[cfg(all(feature = "webgl", not(feature = "glow")))]
-    if let Ok(webgl2_painter) = webgl2::WebGl2Painter::new(canvas_id) {
-        tracing::debug!("Using WebGL2 backend");
-        Ok(Box::new(webgl2_painter))
-    } else {
-        tracing::debug!("Falling back to WebGL1 backend");
-        let webgl1_painter = webgl1::WebGlPainter::new(canvas_id)?;
-        Ok(Box::new(webgl1_painter))
-    }
-
-    #[cfg(all(not(feature = "webgl"), not(feature = "glow")))]
-    compile_error!("Either the 'glow' or 'webgl' feature of egui_web must be enabled!");
+    ))
 }
 
 // ----------------------------------------------------------------------------
@@ -155,7 +140,7 @@ fn test_parse_query() {
 pub struct AppRunner {
     pub(crate) frame: epi::Frame,
     egui_ctx: egui::Context,
-    painter: Box<dyn Painter>,
+    painter: Box<dyn WebPainter>,
     pub(crate) input: WebInput,
     app: Box<dyn epi::App>,
     pub(crate) needs_repaint: std::sync::Arc<NeedRepaint>,

egui_web/src/glow_wrapping.rs

@@ -32,11 +32,19 @@ impl WrappedGlowPainter {
     }
 }
 
-impl crate::Painter for WrappedGlowPainter {
+impl crate::WebPainter for WrappedGlowPainter {
+    fn name(&self) -> &'static str {
+        "egui_web"
+    }
+
     fn max_texture_side(&self) -> usize {
         self.painter.max_texture_side()
     }
 
+    fn canvas_id(&self) -> &str {
+        &self.canvas_id
+    }
+
     fn set_texture(&mut self, tex_id: egui::TextureId, delta: &egui::epaint::ImageDelta) {
         self.painter.set_texture(&self.glow_ctx, tex_id, delta);
     }
@@ -45,18 +53,6 @@ impl crate::Painter for WrappedGlowPainter {
         self.painter.free_texture(&self.glow_ctx, tex_id);
     }
 
-    fn debug_info(&self) -> String {
-        format!(
-            "Stored canvas size: {} x {}",
-            self.canvas.width(),
-            self.canvas.height(),
-        )
-    }
-
-    fn canvas_id(&self) -> &str {
-        &self.canvas_id
-    }
-
     fn clear(&mut self, clear_color: Rgba) {
         let canvas_dimension = [self.canvas.width(), self.canvas.height()];
         egui_glow::painter::clear(&self.glow_ctx, canvas_dimension, clear_color)
@@ -76,10 +72,6 @@ impl crate::Painter for WrappedGlowPainter {
         );
         Ok(())
     }
-
-    fn name(&self) -> &'static str {
-        "egui_web (glow)"
-    }
 }
 
 /// Returns glow context and shader prefix.

egui_web/src/lib.rs

@@ -15,26 +15,20 @@
 #![warn(clippy::all, rustdoc::missing_crate_level_docs, rust_2018_idioms)]
 
 pub mod backend;
-#[cfg(feature = "glow")]
 mod glow_wrapping;
 mod input;
 mod painter;
 pub mod screen_reader;
 mod text_agent;
 
-#[cfg(feature = "webgl")]
-pub mod webgl1;
-#[cfg(feature = "webgl")]
-pub mod webgl2;
-
 pub use backend::*;
 
 use egui::mutex::{Mutex, MutexGuard};
 pub use wasm_bindgen;
 pub use web_sys;
 
 use input::*;
-pub use painter::Painter;
+pub use painter::WebPainter;
 use web_sys::EventTarget;
 
 use std::collections::BTreeMap;

egui_web/src/painter.rs

@@ -1,18 +1,19 @@
 use wasm_bindgen::prelude::JsValue;
 
-pub trait Painter {
+/// What is needed to paint egui.
+pub trait WebPainter {
+    fn name(&self) -> &'static str;
+
     /// Max size of one side of a texture.
     fn max_texture_side(&self) -> usize;
 
+    /// id of the canvas html element containing the rendering
+    fn canvas_id(&self) -> &str;
+
     fn set_texture(&mut self, tex_id: egui::TextureId, delta: &egui::epaint::ImageDelta);
 
     fn free_texture(&mut self, tex_id: egui::TextureId);
 
-    fn debug_info(&self) -> String;
-
-    /// id of the canvas html element containing the rendering
-    fn canvas_id(&self) -> &str;
-
     fn clear(&mut self, clear_color: egui::Rgba);
 
     fn paint_meshes(
@@ -21,8 +22,6 @@ pub trait Painter {
         pixels_per_point: f32,
     ) -> Result<(), JsValue>;
 
-    fn name(&self) -> &'static str;
-
     fn paint_and_update_textures(
         &mut self,
         clipped_meshes: Vec<egui::ClippedMesh>,