init

src/main.rs

@@ -0,0 +1,72 @@
+// 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.
+
+use druid::widget::{Button, Flex, Label};
+use druid::{
+    AppLauncher, Data, Env, FontDescriptor, FontFamily, Lens, LocalizedString, UnitPoint, Widget,
+    WidgetExt, WindowDesc,
+};
+
+const VERTICAL_WIDGET_SPACING: f64 = 20.0;
+const WINDOW_TITLE: LocalizedString<HelloState> = LocalizedString::new("Hello World!");
+
+#[derive(Clone, Data, Lens)]
+struct HelloState {
+    value: u8,
+}
+
+pub fn main() {
+    // describe the main window
+    let main_window = WindowDesc::new(build_root_widget)
+        .title(WINDOW_TITLE)
+        .window_size((400.0, 400.0));
+
+    // create the initial app state
+    let initial_state = HelloState {
+        value: 0,
+    };
+
+    // start the application
+    AppLauncher::with_window(main_window)
+        .launch(initial_state)
+        .expect("Failed to launch application");
+}
+
+fn build_root_widget() -> impl Widget<HelloState> {
+    // a label that will determine its text based on the current app data.
+    let label = Label::new(|data: &HelloState, _env: &Env| {
+            format!("{} %", data.value)
+    })
+    .with_font(FontDescriptor::new(FontFamily::SERIF).with_size(32.0))
+    .align_horizontal(UnitPoint::CENTER);
+
+    let button_inc = Button::new("inc")
+        .on_click(|_ctx, data: &mut HelloState, _env| data.value += 1)
+        .padding(5.0);
+
+    let button_dec = Button::new("dec")
+        .on_click(|_ctx, data: &mut HelloState, _env| data.value -= 1)
+        .padding(5.0);
+
+    let inc_dec_row = Flex::row()
+        .with_child(button_inc)
+        .with_child(button_dec)
+        .align_horizontal(UnitPoint::CENTER);
+
+    Flex::column()
+        .with_child(label)
+        .with_spacer(VERTICAL_WIDGET_SPACING)
+        .with_child(inc_dec_row)
+        .align_vertical(UnitPoint::CENTER)
+}