implement menu example

Author: xarvic

druid/examples/menu.rs

@@ -0,0 +1,127 @@
+// Copyright 2019 The Druid Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! This is a very small example of how to use menus.
+//! It does the almost bare minimum while still being useful.
+
+// On Windows platform, don't show a console when opening the app.
+#![windows_subsystem = "windows"]
+
+use druid::widget::prelude::*;
+use druid::widget::{Flex, Label};
+use druid::{AppDelegate, AppLauncher, Command, Data, DelegateCtx, Handled, Lens, Menu, MenuItem, Selector, Target, WidgetExt, WindowDesc};
+
+const COMMAND: Selector = Selector::new("custom_Selector");
+
+#[derive(Clone, Data, Lens)]
+struct AppState {
+    option: bool,
+    value: usize,
+}
+
+pub fn main() {
+
+
+    // describe the main window
+    let main_window = WindowDesc::new(build_root_widget())
+        .title("Hello World!")
+        .window_size((400.0, 400.0))
+        .menu(|_, _, _|build_menu());
+
+    // create the initial app state
+    let initial_state: AppState = AppState {
+        option: false,
+        value: 0,
+    };
+
+    // start the application. Here we pass in the application state.
+    AppLauncher::with_window(main_window)
+        .log_to_console()
+        .delegate(Delegate)
+        .launch(initial_state)
+        .expect("Failed to launch application");
+}
+
+fn build_root_widget() -> impl Widget<AppState> {
+    Flex::column()
+        .with_child(Label::new(|data: &AppState, _: &_|format!("Current value: {}", data.value)))
+        .with_default_spacer()
+        .with_child(Label::new(|data: &AppState, _: &_|format!("IS selected: {}", data.option)))
+        .center()
+}
+
+fn build_menu() -> Menu<AppState> {
+    let menu = Menu::new("Druid Menu")
+        .entry(
+            MenuItem::new("Send Command")
+                .command(COMMAND)
+        )
+        .separator()
+        .entry(
+            MenuItem::new("Change value")
+                .on_activate(|_, data: &mut AppState, _|data.value = (data.value + 1) % 4)
+        )
+        .entry(
+            MenuItem::new("1 Selected")
+                .on_activate(|_, data: &mut AppState, _|if data.value == 1 {data.value = 0} else {data.value = 1})
+                .selected_if(|data: &AppState, _|data.value == 1)
+        )
+        .entry(
+            MenuItem::new("2 Selected")
+                .on_activate(|_, data: &mut AppState, _|if data.value == 2 {data.value = 0} else {data.value = 2})
+                .selected_if(|data: &AppState, _|data.value == 2)
+        )
+        .entry(
+            MenuItem::new("3 Selected")
+                .on_activate(|_, data: &mut AppState, _|if data.value == 3 {data.value = 0} else {data.value = 3})
+                .selected_if(|data: &AppState, _|data.value == 3)
+        )
+        .separator()
+        .entry(
+            MenuItem::new("CheckBox")
+                .on_activate(|_, data: &mut AppState, _|data.option = !data.option)
+                .selected_if(|data: &AppState, _|data.option)
+        )
+        .entry(
+            MenuItem::new("Disabled")
+                .on_activate(|_, _, _|panic!("disabled Menu Item was activated!"))
+                .enabled(false)
+
+        )
+        .entry(
+            MenuItem::new("Disabled Selectable")
+                .on_activate(|_, _, _|panic!("disabled Menu Item was activated!"))
+                .selected(false)
+                .enabled(false)
+        )
+        //we dont add new menu items based on data!
+        .rebuild_on(|_, _, _|false);
+
+    Menu::empty()
+        .entry(menu)
+
+}
+
+struct Delegate;
+
+impl AppDelegate<AppState> for Delegate {
+    fn command(&mut self, _: &mut DelegateCtx, _: Target, cmd: &Command, _: &mut AppState, _: &Env) -> Handled {
+        if cmd.is(COMMAND) {
+            println!("Clicked \"Send Command\"!");
+            Handled::Yes
+        } else {
+            Handled::No
+        }
+    }
+}