MatchEvent Trait

The MatchEvent trait provides a framework for handling a wide array of events, encompassing application lifecycle, user interactions, network responses, and more.

Whenever there's a need to handle events for widgets, you should opt to implement this trait rather than crafting your own implementation.

MatchEvent Functions

The MatchEvent trait encapsulates various event handling functions:

• handle_startup: Initializes event handling.
• handle_shutdown: Handles shutdown events.
• handle_foreground: Manages app foreground entry events.
• handle_background: Manages app background entry events.
• handle_pause: Manages app pause events.
• handle_resume: Manages app resume events.
• handle_app_got_focus: Handles app focus acquisition events.
• handle_app_lost_focus: Handles app focus loss events.
• handle_next_frame: Prepares for the next frame events.
• handle_action: Handles individual action events.
• handle_actions: Handles multiple action events.
• handle_signal: Manages signal events (may be used for custom events or messaging).
• handle_audio_devices: Manages audio device events.
• handle_midi_ports: Manages MIDI port events.
• handle_video_inputs: Manages video input events.
• handle_http_response: Handles HTTP response events.
• handle_http_request_error: Handles HTTP request error events.
• handle_http_progress: Manages HTTP progress events.
• handle_network_responses: Handles network response events, calling corresponding handlers based on response type.
• handle_draw: Manages drawing events.
• handle_timer: Manages timer events.
• handle_draw_2d: Manages 2D drawing events.
• handle_key_down: Handles key press events.
• handle_key_up: Handles key release events.
• handle_back_pressed: Manages back button events (commonly used in mobile devices).
• match_event: Matches and processes incoming events, calling corresponding handlers based on the event type.
• match_event_with_draw_2d: Specialized event matching and handling logic for drawing events, using Cx2d as context.

Implementing MatchEvent

#![allow(unused)]
fn main() {
/// Struct requiring implementation
#[derive(Live, LiveHook)]
pub struct App {
    #[live]
    ui: WidgetRef,
}

/// Implementing the MatchEvent trait
impl MatchEvent for App {
    // Implementation of handle_actions
    fn handle_actions(&mut self, cx: &mut Cx, actions:&Actions) {
        // Handling button click events
        // Use id! macro to access button: btn1
        if self.ui.button(id!(btn1)).clicked(&actions) {
            self.counter += 1;
            let label = self.ui.label(id!(t_label));
            // Setting text
            label.set_text(&format!("Click Number: {}", self.counter));
            // Redrawing label
            label.redraw(cx);
        }
    }
}

impl AppMain for App {
    fn handle_event(&mut self, cx: &mut Cx, event: &Event) {
        // Registering match event for it to work
        self.match_event(cx, event);
        self.ui.handle_event(cx, event, &mut Scope::empty());
    }
}
}

Complete Example

#![allow(unused)]
fn main() {
use makepad_widgets::*;
live_design! {
    import makepad_widgets::base::*;
    import makepad_widgets::theme_desktop_dark::*;
    App = {{App}} { 
        ui: <Window> {
            show_bg: true, 
            draw_bg: { color: #1C2630 }, 
            width: Fill, 
            height: Fill,  
            body = <View> {
                flow: Down,
                align: {x: 0.5, y: 0.5},  
                btn1 = <Button> {
                    text: "Click Me!"
                } 
                t_label = <Label> { 
                    margin: {top: 16.0},
                    text: "Click Number: 0",
                    draw_text: {
                        color: #f, 
                        text_style: { 
                            font: {path: dep("crate://makepad-widgets/resources/IBMPlexSans-SemiBold.ttf")}, 
                        } 
                    }
                } 
            } 
        } 
    }
}
#[derive(Live, LiveHook)]
pub struct App {
    #[live]
    ui: WidgetRef,
    #[rust]
    counter: usize,
}

impl LiveRegister for App {
    fn live_register(cx: &mut Cx) {
        crate::makepad_widgets::live_design(cx);
    }
}

impl MatchEvent for App {
    fn handle_actions(&mut self, cx: &mut Cx, actions:&Actions) {
        if self.ui.button(id!(btn1)).clicked(&actions) {
            self.counter += 1;
            let label = self.ui.label(id!(t_label));
            label.set_text(&format!("Click Number: {}", self.counter));
            label.redraw(cx);
        }
    }
}

impl AppMain for App {
    fn handle_event(&mut self, cx: &mut Cx, event: &Event) {
        self.match_event(cx, event);
        self.ui.handle_event(cx, event, &mut Scope::empty());
    }
}

app_main!(App);
}