frontend: the advoware GUI

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

frontend/examples/clear.rs

@@ -0,0 +1,67 @@
+use orbtk::prelude::*;
+
+#[derive(Default, AsAny)]
+pub struct MainViewState {
+    clear: bool,
+}
+
+impl MainViewState {
+    // Sets an action the state
+    fn clear(&mut self) {
+        self.clear = true;
+    }
+}
+
+impl State for MainViewState {
+    fn update(&mut self, _: &mut Registry, ctx: &mut Context<'_>) {
+        if self.clear {
+            // Clears the text property of MainView and because
+            // of the sharing also the text of the TextBox.
+            ctx.widget().set("text", String16::from(""));
+            self.clear = false;
+        }
+    }
+}
+
+widget!(MainView<MainViewState> {
+    text: String16
+});
+
+impl Template for MainView {
+    fn template(self, id: Entity, ctx: &mut BuildContext) -> Self {
+        self.name("MainView").child(
+            Stack::create()
+                .orientation("horizontal")
+                // By injecting the id of the parent the text property
+                // is shared between the MainView and the TextBox. This
+                // means both references the same String16 object.
+                .child(TextBox::create().height(32.0).text(id).build(ctx))
+                .child(
+                    Button::create()
+                        .margin((8.0, 0.0, 0.0, 0.0))
+                        // mouse click event handler
+                        .on_click(move |states, _| {
+                            // Calls clear of the state of MainView
+                            states.get_mut::<MainViewState>(id).clear();
+                            true
+                        })
+                        .text("Clear")
+                        .build(ctx),
+                )
+                .build(ctx),
+        )
+    }
+}
+
+fn main() {
+    Application::new()
+        .window(|ctx| {
+            Window::create()
+                .title("OrbTk - minimal example")
+                .position((100.0, 100.0))
+                .size(420.0, 730.0)
+                .child(MainView::create().margin(4.0).build(ctx))
+                .build(ctx)
+        })
+        .run();
+}