Keyboard shortcut helpers

CHANGELOG.md

@@ -9,6 +9,9 @@ NOTE: [`epaint`](crates/epaint/CHANGELOG.md), [`eframe`](crates/eframe/CHANGELOG
 
 ### Added ⭐
 * Added helper functions for animating panels that collapse/expand ([#2190](https://github.com/emilk/egui/pull/2190)).
+* Added `Context::os/Context::set_os` to query/set what operating system egui believes it is running on ([#2202](https://github.com/emilk/egui/pull/2202)).
+* Added `Button::shortcut_text` for showing keyboard shortcuts in menu buttons ([#2202](https://github.com/emilk/egui/pull/2202)).
+* Added `egui::KeyboardShortcut` for showing keyboard shortcuts in menu buttons ([#2202](https://github.com/emilk/egui/pull/2202)).
 
 ### Fixed 🐛
 * ⚠️ BREAKING: Fix text being too small ([#2069](https://github.com/emilk/egui/pull/2069)).

crates/eframe/CHANGELOG.md

@@ -14,7 +14,7 @@ NOTE: [`egui-winit`](../egui-winit/CHANGELOG.md), [`egui_glium`](../egui_glium/C
 * Added `center` to `NativeOptions` and `monitor_size` to `WindowInfo` on desktop ([#2035](https://github.com/emilk/egui/pull/2035)).
 * Web: you can access your application from JS using `AppRunner::app_mut`. See `crates/egui_demo_app/src/lib.rs`.
 * Web: You can now use WebGL on top of `wgpu` by enabling the `wgpu` feature (and disabling `glow` via disabling default features) ([#2107](https://github.com/emilk/egui/pull/2107)).
-
+* Web: Add `WebInfo::user_agent` ([#2202](https://github.com/emilk/egui/pull/2202)).
 
 
 ## 0.19.0 - 2022-08-20

crates/eframe/src/epi.rs

@@ -767,6 +767,9 @@ impl Frame {
 #[derive(Clone, Debug)]
 #[cfg(target_arch = "wasm32")]
 pub struct WebInfo {
+    /// The browser user agent.
+    pub user_agent: String,
+
     /// Information about the URL.
     pub location: Location,
 }

crates/eframe/src/web/backend.rs

@@ -87,6 +87,10 @@ impl IsDestroyed {
 
 // ----------------------------------------------------------------------------
 
+fn user_agent() -> Option<String> {
+    web_sys::window()?.navigator().user_agent().ok()
+}
+
 fn web_location() -> epi::Location {
     let location = web_sys::window().unwrap().location();
 
@@ -198,6 +202,7 @@ impl AppRunner {
 
         let info = epi::IntegrationInfo {
             web_info: epi::WebInfo {
+                user_agent: user_agent().unwrap_or_default(),
                 location: web_location(),
             },
             system_theme,
@@ -207,6 +212,9 @@ impl AppRunner {
         let storage = LocalStorage::default();
 
         let egui_ctx = egui::Context::default();
+        egui_ctx.set_os(egui::os::OperatingSystem::from_user_agent(
+            &user_agent().unwrap_or_default(),
+        ));
         load_memory(&egui_ctx);
 
         let theme = system_theme.unwrap_or(web_options.default_theme);

crates/egui/src/context.rs

@@ -3,7 +3,8 @@ use std::sync::Arc;
 
 use crate::{
     animation_manager::AnimationManager, data::output::PlatformOutput, frame_state::FrameState,
-    input_state::*, layers::GraphicLayers, memory::Options, output::FullOutput, TextureHandle, *,
+    input_state::*, layers::GraphicLayers, memory::Options, os::OperatingSystem,
+    output::FullOutput, TextureHandle, *,
 };
 use epaint::{mutex::*, stats::*, text::Fonts, textures::TextureFilter, TessellationOptions, *};
 
@@ -36,6 +37,8 @@ struct ContextImpl {
     animation_manager: AnimationManager,
     tex_manager: WrappedTextureManager,
 
+    os: OperatingSystem,
+
     input: InputState,
 
     /// State that is collected during a frame and then cleared
@@ -563,6 +566,59 @@ impl Context {
     pub fn tessellation_options(&self) -> RwLockWriteGuard<'_, TessellationOptions> {
         RwLockWriteGuard::map(self.write(), |c| &mut c.memory.options.tessellation_options)
     }
+
+    /// What operating system are we running on?
+    ///
+    /// When compiling natively, this is
+    /// figured out from the `target_os`.
+    ///
+    /// For web, this can be figured out from the user-agent,
+    /// and is done so by [`eframe`](https://github.com/emilk/egui/tree/master/crates/eframe).
+    pub fn os(&self) -> OperatingSystem {
+        self.read().os
+    }
+
+    /// Set the operating system we are running on.
+    ///
+    /// If you are writing wasm-based integration for egui you
+    /// may want to set this based on e.g. the user-agent.
+    pub fn set_os(&self, os: OperatingSystem) {
+        self.write().os = os;
+    }
+
+    /// Format the given shortcut in a human-readable way (e.g. `Ctrl+Shift+X`).
+    ///
+    /// Can be used to get the text for [`Button::shortcut_text`].
+    pub fn format_shortcut(&self, shortcut: &KeyboardShortcut) -> String {
+        let os = self.os();
+
+        let is_mac = matches!(os, OperatingSystem::Mac | OperatingSystem::IOS);
+
+        let can_show_symbols = || {
+            let ModifierNames {
+                alt,
+                ctrl,
+                shift,
+                mac_cmd,
+                ..
+            } = ModifierNames::SYMBOLS;
+
+            let font_id = TextStyle::Body.resolve(&self.style());
+            let fonts = self.fonts();
+            let mut fonts = fonts.lock();
+            let font = fonts.fonts.font(&font_id);
+            font.has_glyphs(alt)
+                && font.has_glyphs(ctrl)
+                && font.has_glyphs(shift)
+                && font.has_glyphs(mac_cmd)
+        };
+
+        if is_mac && can_show_symbols() {
+            shortcut.format(&ModifierNames::SYMBOLS, is_mac)
+        } else {
+            shortcut.format(&ModifierNames::NAMES, is_mac)
+        }
+    }
 }
 
 impl Context {