Make Application and Sandbox return a Result

graphics/src/error.rs

@@ -0,0 +1,7 @@
+/// A graphical error that occurred while running an application.
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    /// A suitable graphics adapter or device could not be found
+    #[error("a suitable graphics adapter or device could not be found")]
+    AdapterNotFound,
+}

graphics/src/lib.rs

@@ -9,6 +9,7 @@
 #![forbid(rust_2018_idioms)]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 mod antialiasing;
+mod error;
 mod primitive;
 mod renderer;
 mod transformation;
@@ -29,6 +30,7 @@ pub use widget::*;
 pub use antialiasing::Antialiasing;
 pub use backend::Backend;
 pub use defaults::Defaults;
+pub use error::Error;
 pub use layer::Layer;
 pub use primitive::Primitive;
 pub use renderer::Renderer;

graphics/src/window/compositor.rs

@@ -1,4 +1,4 @@
-use crate::{Color, Viewport};
+use crate::{Color, Error, Viewport};
 use iced_native::mouse;
 use raw_window_handle::HasRawWindowHandle;
 
@@ -19,7 +19,7 @@ pub trait Compositor: Sized {
     /// Creates a new [`Backend`].
     ///
     /// [`Backend`]: trait.Backend.html
-    fn new(settings: Self::Settings) -> (Self, Self::Renderer);
+    fn new(settings: Self::Settings) -> Result<(Self, Self::Renderer), Error>;
 
     /// Crates a new [`Surface`] for the given window.
     ///

graphics/src/window/gl_compositor.rs

@@ -1,4 +1,4 @@
-use crate::{Color, Size, Viewport};
+use crate::{Color, Error, Size, Viewport};
 use iced_native::mouse;
 
 use core::ffi::c_void;
@@ -41,7 +41,7 @@ pub trait GLCompositor: Sized {
     unsafe fn new(
         settings: Self::Settings,
         loader_function: impl FnMut(&str) -> *const c_void,
-    ) -> (Self, Self::Renderer);
+    ) -> Result<(Self, Self::Renderer), Error>;
 
     /// Returns the amount of samples that should be used when configuring
     /// an OpenGL context for this [`Compositor`].