Better error reporting

crates/eframe/src/lib.rs

@@ -313,6 +313,11 @@ pub enum Error {
     #[error("Found no glutin configs matching the template: {0:?}. Error: {1:?}")]
     NoGlutinConfigs(glutin::config::ConfigTemplate, Box<dyn std::error::Error>),
 
+    /// An error from [`glutin`] when using [`glow`].
+    #[cfg(feature = "glow")]
+    #[error("egui_glow: {0}")]
+    OpenGL(#[from] egui_glow::PainterError),
+
     /// An error from [`wgpu`].
     #[cfg(feature = "wgpu")]
     #[error("WGPU error: {0}")]

crates/eframe/src/native/run.rs

@@ -1021,17 +1021,18 @@ mod glow_integration {
                 .get_mut(&viewport_id)
                 .expect("viewport doesn't exist");
 
-            let window = viewport.window.get_or_insert_with(|| {
+            let window = if let Some(window) = &mut viewport.window {
+                window
+            } else {
                 log::trace!("Window doesn't exist yet. Creating one now with finalize_window");
-                Rc::new(
-                    glutin_winit::finalize_window(
+                viewport
+                    .window
+                    .insert(Rc::new(glutin_winit::finalize_window(
                         event_loop,
                         create_winit_window_builder(&viewport.builder),
                         &self.gl_config,
-                    )
-                    .expect("failed to finalize glutin window"),
-                )
-            });
+                    )?))
+            };
 
             {
                 // surface attributes
@@ -1330,8 +1331,7 @@ mod glow_integration {
                 }))
             };
 
-            let painter = egui_glow::Painter::new(gl, "", native_options.shader_version)
-                .unwrap_or_else(|err| panic!("An OpenGL error occurred: {err}\n"));
+            let painter = egui_glow::Painter::new(gl, "", native_options.shader_version)?;
 
             Ok((glutin_window_context, painter))
         }
@@ -1821,22 +1821,27 @@ mod wgpu_integration {
 
             let viewport_id = self.ids.this;
 
-            if let Ok(new_window) = create_winit_window_builder(&self.builder).build(event_loop) {
-                windows_id.insert(new_window.id(), viewport_id);
+            match create_winit_window_builder(&self.builder).build(event_loop) {
+                Ok(new_window) => {
+                    windows_id.insert(new_window.id(), viewport_id);
 
-                if let Err(err) =
-                    pollster::block_on(painter.set_window(viewport_id, Some(&new_window)))
-                {
-                    log::error!("on set_window: viewport_id {viewport_id:?} {err}");
+                    if let Err(err) =
+                        pollster::block_on(painter.set_window(viewport_id, Some(&new_window)))
+                    {
+                        log::error!("on set_window: viewport_id {viewport_id:?} {err}");
+                    }
+
+                    self.egui_winit = Some(egui_winit::State::new(
+                        event_loop,
+                        Some(new_window.scale_factor() as f32),
+                        painter.max_texture_side(),
+                    ));
+
+                    self.window = Some(Rc::new(new_window));
+                }
+                Err(err) => {
+                    log::error!("Failed to create window: {err}");
                 }
-
-                self.egui_winit = Some(egui_winit::State::new(
-                    event_loop,
-                    Some(new_window.scale_factor() as f32),
-                    painter.max_texture_side(),
-                ));
-
-                self.window = Some(Rc::new(new_window));
             }
         }
     }

crates/egui/src/load.rs

@@ -58,7 +58,7 @@ mod texture_loader;
 use std::borrow::Cow;
 use std::fmt::Debug;
 use std::ops::Deref;
-use std::{error::Error as StdError, fmt::Display, sync::Arc};
+use std::{fmt::Display, sync::Arc};
 
 use ahash::HashMap;
 
@@ -118,7 +118,7 @@ impl Display for LoadError {
     }
 }
 
-impl StdError for LoadError {}
+impl std::error::Error for LoadError {}
 
 pub type Result<T, E = LoadError> = std::result::Result<T, E>;
 

crates/egui_glow/src/lib.rs

@@ -13,7 +13,7 @@
 
 pub mod painter;
 pub use glow;
-pub use painter::{CallbackFn, Painter};
+pub use painter::{CallbackFn, Painter, PainterError};
 mod misc_util;
 mod shader_version;
 mod vao;

crates/egui_glow/src/painter.rs

@@ -34,6 +34,24 @@ impl TextureFilterExt for egui::TextureFilter {
     }
 }
 
+#[derive(Debug)]
+pub struct PainterError(String);
+
+impl std::error::Error for PainterError {}
+
+impl std::fmt::Display for PainterError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "OpenGL: {}", self.0)
+    }
+}
+
+impl From<String> for PainterError {
+    #[inline]
+    fn from(value: String) -> Self {
+        Self(value)
+    }
+}
+
 /// An OpenGL painter using [`glow`].
 ///
 /// This is responsible for painting egui and managing egui textures.
@@ -103,7 +121,7 @@ impl Painter {
         gl: Arc<glow::Context>,
         shader_prefix: &str,
         shader_version: Option<ShaderVersion>,
-    ) -> Result<Painter, String> {
+    ) -> Result<Painter, PainterError> {
         crate::profile_function!();
         crate::check_for_gl_error_even_in_release!(&gl, "before Painter::new");
 
@@ -121,7 +139,7 @@ impl Painter {
         if gl.version().major < 2 {
             // this checks on desktop that we are not using opengl 1.1 microsoft sw rendering context.
             // ShaderVersion::get fn will segfault due to SHADING_LANGUAGE_VERSION (added in gl2.0)
-            return Err("egui_glow requires opengl 2.0+. ".to_owned());
+            return Err(PainterError("egui_glow requires opengl 2.0+. ".to_owned()));
         }
 
         let max_texture_side = unsafe { gl.get_parameter_i32(glow::MAX_TEXTURE_SIZE) } as usize;