add example with simple text input

Cargo.toml

@@ -1127,6 +1127,16 @@ description = "Prints out all touch inputs"
 category = "Input"
 wasm = false
 
+[[example]]
+name = "text_input"
+path = "examples/input/text_input.rs"
+
+[package.metadata.example.text_input]
+name = "Text Input"
+description = "Simple text input with IME support"
+category = "Input"
+wasm = false
+
 # Reflection
 [[example]]
 name = "reflection"

examples/README.md

@@ -232,6 +232,7 @@ Example | Description
 [Mouse Grab](../examples/input/mouse_grab.rs) | Demonstrates how to grab the mouse, locking the cursor to the app's screen
 [Mouse Input](../examples/input/mouse_input.rs) | Demonstrates handling a mouse button press/release
 [Mouse Input Events](../examples/input/mouse_input_events.rs) | Prints out all mouse events (buttons, movement, etc.)
+[Text Input](../examples/input/text_input.rs) | Simple text input with IME support
 [Touch Input](../examples/input/touch_input.rs) | Displays touch presses, releases, and cancels
 [Touch Input Events](../examples/input/touch_input_events.rs) | Prints out all touch inputs
 

examples/input/text_input.rs

@@ -0,0 +1,201 @@
+//! Simple text input support
+//!
+//! Return creates a new line, backspace removes the last character.
+//! Clicking toggle IME (Input Method Editor) support, but the font used as limited support of characters.
+//! You should change the provided font with another one to test other languages input.
+
+use bevy::{input::keyboard::KeyboardInput, prelude::*};
+
+fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .add_startup_system(setup_scene)
+        .add_system(toggle_ime)
+        .add_system(listen_ime_events)
+        .add_system(listen_received_character_events)
+        .add_system(listen_keyboard_input_events)
+        .add_system(bubbling_text)
+        .run();
+}
+
+fn setup_scene(mut commands: Commands, asset_server: Res<AssetServer>) {
+    commands.spawn(Camera2dBundle::default());
+
+    let font = asset_server.load("fonts/FiraMono-Medium.ttf");
+
+    commands.spawn(
+        TextBundle::from_sections([
+            TextSection {
+                value: "IME Enabled: ".to_string(),
+                style: TextStyle {
+                    font: font.clone_weak(),
+                    font_size: 20.0,
+                    color: Color::WHITE,
+                },
+            },
+            TextSection {
+                value: "false\n".to_string(),
+                style: TextStyle {
+                    font: font.clone_weak(),
+                    font_size: 30.0,
+                    color: Color::WHITE,
+                },
+            },
+            TextSection {
+                value: "IME Active: ".to_string(),
+                style: TextStyle {
+                    font: font.clone_weak(),
+                    font_size: 20.0,
+                    color: Color::WHITE,
+                },
+            },
+            TextSection {
+                value: "false\n".to_string(),
+                style: TextStyle {
+                    font: font.clone_weak(),
+                    font_size: 30.0,
+                    color: Color::WHITE,
+                },
+            },
+            TextSection {
+                value: "click to toggle IME, press return to start a new line\n\n".to_string(),
+                style: TextStyle {
+                    font: font.clone_weak(),
+                    font_size: 18.0,
+                    color: Color::WHITE,
+                },
+            },
+            TextSection {
+                value: "".to_string(),
+                style: TextStyle {
+                    font,
+                    font_size: 25.0,
+                    color: Color::WHITE,
+                },
+            },
+        ])
+        .with_style(Style {
+            position_type: PositionType::Absolute,
+            position: UiRect {
+                top: Val::Px(10.0),
+                left: Val::Px(10.0),
+                ..default()
+            },
+            ..default()
+        }),
+    );
+
+    commands.spawn(Text2dBundle {
+        text: Text::from_section(
+            "".to_string(),
+            TextStyle {
+                font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+                font_size: 100.0,
+                color: Color::WHITE,
+            },
+        ),
+        ..default()
+    });
+}
+
+fn toggle_ime(
+    input: Res<Input<MouseButton>>,
+    mut windows: Query<&mut Window>,
+    mut text: Query<&mut Text, With<Node>>,
+) {
+    if input.just_pressed(MouseButton::Left) {
+        let mut window = windows.single_mut();
+
+        window.ime_position = window
+            .cursor_position()
+            .map(|p| Vec2::new(p.x, window.height() - p.y))
+            .unwrap();
+        window.ime_enabled = !window.ime_enabled;
+
+        let mut text = text.single_mut();
+        text.sections[1].value = format!("{}\n", window.ime_enabled);
+    }
+}
+
+#[derive(Component)]
+struct Bubble {
+    timer: Timer,
+}
+
+#[derive(Component)]
+struct ImePreedit;
+
+fn bubbling_text(
+    mut commands: Commands,
+    mut bubbles: Query<(Entity, &mut Transform, &mut Bubble)>,
+    time: Res<Time>,
+) {
+    for (entity, mut transform, mut bubble) in bubbles.iter_mut() {
+        if bubble.timer.tick(time.delta()).just_finished() {
+            commands.entity(entity).despawn();
+        }
+        transform.translation.y += time.delta_seconds() * 100.0;
+    }
+}
+
+fn listen_ime_events(
+    mut events: EventReader<Ime>,
+    mut status_text: Query<&mut Text, With<Node>>,
+    mut edit_text: Query<&mut Text, (Without<Node>, Without<Bubble>)>,
+) {
+    for event in events.iter() {
+        match event {
+            Ime::Preedit { value, cursor, .. } if !cursor.is_none() => {
+                status_text.single_mut().sections[5].value = format!("IME buffer: {value}");
+            }
+            Ime::Preedit { cursor, .. } if cursor.is_none() => {
+                status_text.single_mut().sections[5].value = "".to_string();
+            }
+            Ime::Commit { value, .. } => {
+                edit_text.single_mut().sections[0].value.push_str(value);
+            }
+            Ime::Enabled { .. } => {
+                status_text.single_mut().sections[3].value = "true\n".to_string();
+            }
+            Ime::Disabled { .. } => {
+                status_text.single_mut().sections[3].value = "false\n".to_string();
+            }
+            _ => (),
+        }
+    }
+}
+
+fn listen_received_character_events(
+    mut events: EventReader<ReceivedCharacter>,
+    mut edit_text: Query<&mut Text, (Without<Node>, Without<Bubble>)>,
+) {
+    for event in events.iter() {
+        edit_text.single_mut().sections[0].value.push(event.char);
+    }
+}
+
+fn listen_keyboard_input_events(
+    mut commands: Commands,
+    mut events: EventReader<KeyboardInput>,
+    mut edit_text: Query<(Entity, &mut Text), (Without<Node>, Without<Bubble>)>,
+) {
+    for event in events.iter() {
+        match event.key_code {
+            Some(KeyCode::Return) => {
+                let (entity, text) = edit_text.single();
+                commands.entity(entity).insert(Bubble {
+                    timer: Timer::from_seconds(5.0, TimerMode::Once),
+                });
+
+                commands.spawn(Text2dBundle {
+                    text: Text::from_section("".to_string(), text.sections[0].style.clone()),
+                    ..default()
+                });
+            }
+            Some(KeyCode::Back) => {
+                edit_text.single_mut().1.sections[0].value.pop();
+            }
+            _ => continue,
+        }
+    }
+}