Add Ui.input_mut & InputState.ignore_key (#1212)

Author: cat-state

CHANGELOG.md

@@ -8,6 +8,7 @@ NOTE: [`epaint`](epaint/CHANGELOG.md), [`eframe`](eframe/CHANGELOG.md), [`egui_w
 ## Unreleased
 
 ### Added ⭐
+*  `Ui::input_mut` to modify how subsequent widgets see the `InputState` and a convenience method `InputState::consume_key` for shortcuts or hotkeys ([#1212](https://github.com/emilk/egui/pull/1212)). 
 * Much improved font selection ([#1154](https://github.com/emilk/egui/pull/1154)):
   * You can now select any font size and family using `RichText::size` amd `RichText::family` and the new `FontId`.
   * Easily change text styles with `Style::text_styles`.

egui/src/data/input.rs

@@ -264,6 +264,42 @@ pub struct Modifiers {
 }
 
 impl Modifiers {
+    pub fn new() -> Self {
+        Default::default()
+    }
+
+    pub fn alt(self, value: bool) -> Self {
+        Self { alt: value, ..self }
+    }
+
+    pub fn ctrl(self, value: bool) -> Self {
+        Self {
+            ctrl: value,
+            ..self
+        }
+    }
+
+    pub fn shift(self, value: bool) -> Self {
+        Self {
+            shift: value,
+            ..self
+        }
+    }
+
+    pub fn mac_cmd(self, value: bool) -> Self {
+        Self {
+            mac_cmd: value,
+            ..self
+        }
+    }
+
+    pub fn command(self, value: bool) -> Self {
+        Self {
+            command: value,
+            ..self
+        }
+    }
+
     #[inline(always)]
     pub fn is_none(&self) -> bool {
         self == &Self::default()

egui/src/input_state.rs

@@ -192,6 +192,24 @@ impl InputState {
         self.pointer.wants_repaint() || self.scroll_delta != Vec2::ZERO || !self.events.is_empty()
     }
 
+    /// Ignore a key if it was pressed or released this frame. Useful for hotkeys.
+    /// Matches on both key press and key release, consuming them and removing them from `self.events`.
+    /// Returns true if the key was pressed this frame (even if the key release was consumed).
+    pub fn consume_key(&mut self, modifiers: Modifiers, key: Key) -> bool {
+        self.events.retain(|event| {
+            !matches!(
+                event,
+                Event::Key {
+                    key: ev_key,
+                    modifiers: ev_mods,
+                    ..
+                } if *ev_key == key && *ev_mods == modifiers
+            )
+        });
+
+        self.keys_down.remove(&key)
+    }
+
     /// Was the given key pressed this frame?
     pub fn key_pressed(&self, desired_key: Key) -> bool {
         self.num_presses(desired_key) > 0

egui/src/ui.rs

@@ -338,6 +338,21 @@ impl Ui {
         self.ctx().input()
     }
 
+    /// The [`InputState`] of the [`Context`] associated with this [`Ui`].
+    /// Equivalent to `.ctx().input_mut()`.
+    ///
+    /// Note that this locks the [`Context`], so be careful with if-let bindings
+    /// like for [`Self::input()`].
+    /// ```
+    /// # egui::__run_test_ui(|ui| {
+    /// ui.input_mut().consume_key(egui::Modifiers::default(), egui::Key::Enter);
+    /// # });
+    /// ```
+    #[inline]
+    pub fn input_mut(&self) -> RwLockWriteGuard<'_, InputState> {
+        self.ctx().input_mut()
+    }
+
     /// The [`Memory`] of the [`Context`] associated with this ui.
     /// Equivalent to `.ctx().memory()`.
     #[inline]

egui_demo_lib/src/easy_mark/easy_mark_editor.rs

@@ -117,59 +117,27 @@ impl EasyMarkEditor {
 
 fn shortcuts(ui: &Ui, code: &mut dyn TextBuffer, ccursor_range: &mut CCursorRange) -> bool {
     let mut any_change = false;
-    for event in &ui.input().events {
-        if let Event::Key {
-            key,
-            pressed: true,
-            modifiers,
-        } = event
+    for (key, surrounding) in [
+        (Key::B, "*"), // *bold*
+        (Key::C, "`"), // `code`
+        (Key::I, "/"), // /italics/
+        (Key::L, "$"), // $subscript$
+        (Key::R, "^"), // ^superscript^
+        (Key::S, "~"), // ~strikethrough~
+        (Key::U, "_"), // _underline_
+    ] {
+        if ui
+            .input_mut()
+            .consume_key(egui::Modifiers::new().command(true), key)
         {
-            if modifiers.command_only() {
-                match &key {
-                    // toggle *bold*
-                    Key::B => {
-                        toggle_surrounding(code, ccursor_range, "*");
-                        any_change = true;
-                    }
-                    // toggle `code`
-                    Key::C => {
-                        toggle_surrounding(code, ccursor_range, "`");
-                        any_change = true;
-                    }
-                    // toggle /italics/
-                    Key::I => {
-                        toggle_surrounding(code, ccursor_range, "/");
-                        any_change = true;
-                    }
-                    // toggle $lowered$
-                    Key::L => {
-                        toggle_surrounding(code, ccursor_range, "$");
-                        any_change = true;
-                    }
-                    // toggle ^raised^
-                    Key::R => {
-                        toggle_surrounding(code, ccursor_range, "^");
-                        any_change = true;
-                    }
-                    // toggle ~strikethrough~
-                    Key::S => {
-                        toggle_surrounding(code, ccursor_range, "~");
-                        any_change = true;
-                    }
-                    // toggle _underline_
-                    Key::U => {
-                        toggle_surrounding(code, ccursor_range, "_");
-                        any_change = true;
-                    }
-                    _ => {}
-                }
-            }
-        }
+            toggle_surrounding(code, ccursor_range, surrounding);
+            any_change = true;
+        };
     }
     any_change
 }
 
-/// E.g. toggle *strong* with `toggle(&mut text, &mut cursor, "*")`
+/// E.g. toggle *strong* with `toggle_surrounding(&mut text, &mut cursor, "*")`
 fn toggle_surrounding(
     code: &mut dyn TextBuffer,
     ccursor_range: &mut CCursorRange,