frontend: the advoware GUI

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

frontend/examples/counter.rs-0.3.1-alpha1

@@ -0,0 +1,111 @@
+use orbtk::api::widget::StatesContext;
+use orbtk::prelude::*;
+
+#[derive(Debug)]
+pub enum Event {
+    Increment(Entity),
+}
+
+#[derive(AsAny, Default)]
+pub struct AppState {
+    events: VecDeque<Event>,
+    pub notes: Entity,
+    count: u32,
+}
+
+//rbtk_api::widget::states_context::StatesContext<'_>
+#[derive(Debug, Copy, Clone)]
+enum Action {
+    Increment(usize),
+}
+
+#[derive(Default, AsAny)]
+pub struct MainViewState {
+    num: usize,
+    action: Option<Action>,
+}
+
+impl MainViewState {
+    fn action(&mut self, action: impl Into<Option<Action>>) {
+	self.action = action.into();
+    }
+}
+
+impl Template for MainView {
+    fn template(self, id: Entity, ctx: &mut BuildContext) -> Self {
+	self.name("MainView")
+	    .counter(0)
+	    .result("Button count: 0")
+	    .child(
+		Button::create()
+		    .selector(Selector::from("button").id("btn"))
+		    .min_size(100.0, 50.0)
+		    .text(("result", id))
+		    .on_click(move |states, _| -> bool {
+			state(id, states).action(Action::Increment(10));
+			true
+		    })
+		    .build(ctx),
+	    )
+    }
+}
+
+impl State for MainViewState {
+    fn update(&mut self, _: &mut Registry, ctx: &mut Context<'_>) {
+	if let Some(action) = self.action {
+	    match action {
+		Action::Increment(digit) => {
+		    *ctx.widget().get_mut::<usize>("counter") += digit as usize;
+		    let counter = *ctx.widget().get::<usize>("counter");
+		    ctx.widget().set(
+			"result",
+			String16::from(format!("Button count: {}", counter)),
+		    );
+		}
+		_ => {}
+	    }
+
+	    // Is it possible to get rid of this line ?
+	    self.action = None;
+	}
+
+	if let Some(event) = self.events.pop_front() {
+	    match event {
+		// Create and append the note to the UI.
+		Event::Increment(entity) => {
+		    if let Some(copy) = Self::fetch_text(ctx, entity) {
+			self.append_note(ctx, copy);
+			let count = self.count + 1;
+			self.count = count;
+			if count == 1 {
+			    ctx.widget().set::<f64>("spacing", 12.0);
+			}
+		    }
+		}
+	    }
+	}
+    }
+}
+
+widget!(MainView<MainViewState> {
+    age:i32,
+    counter:usize,
+    result: String16
+});
+
+fn main() {
+    Application::new()
+	.window(|ctx| {
+	    Window::create()
+		.title("OrbTk - counter example")
+		.position((100.0, 100.0))
+		.size(400.0, 400.0)
+		.child(MainView::create().build(ctx))
+		.build(ctx)
+	})
+	.run();
+}
+
+fn state<'a>(id: Entity, states: &'a mut StatesContext) -> &'a mut MainViewState {
+    states.get_mut(id)
+}