Draft `component` example :tada:

2 files changed, 191 insertions, 0 deletions

diff --git a/examples/component/Cargo.toml b/examples/component/Cargo.toml
new file mode 100644
index 00000000..5761db9f
--- /dev/null
+++ b/examples/component/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "component"
+version = "0.1.0"
+authors = ["Héctor Ramón Jiménez <hector0193@gmail.com>"]
+edition = "2018"
+publish = false
+
+[dependencies]
+iced = { path = "../..", features = ["debug"] }
+iced_native = { path = "../../native" }
+iced_lazy = { path = "../../lazy" }
diff --git a/examples/component/src/main.rs b/examples/component/src/main.rs
new file mode 100644
index 00000000..58d3f354
--- /dev/null
+++ b/examples/component/src/main.rs
@@ -0,0 +1,180 @@
+use iced::{Container, Element, Length, Sandbox, Settings};
+use numeric_input::NumericInput;
+
+pub fn main() -> iced::Result {
+    Component::run(Settings::default())
+}
+
+#[derive(Default)]
+struct Component {
+    numeric_input: numeric_input::State,
+    value: Option<u32>,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Message {
+    NumericInputChanged(Option<u32>),
+}
+
+impl Sandbox for Component {
+    type Message = Message;
+
+    fn new() -> Self {
+        Self::default()
+    }
+
+    fn title(&self) -> String {
+        String::from("Component - Iced")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::NumericInputChanged(value) => {
+                self.value = value;
+            }
+        }
+    }
+
+    fn view(&mut self) -> Element<Message> {
+        Container::new(NumericInput::new(
+            &mut self.numeric_input,
+            self.value,
+            Message::NumericInputChanged,
+        ))
+        .padding(20)
+        .height(Length::Fill)
+        .center_y()
+        .into()
+    }
+}
+
+mod numeric_input {
+    use iced_lazy::component::{self, Component};
+    use iced_native::alignment::{self, Alignment};
+    use iced_native::text;
+    use iced_native::widget::button::{self, Button};
+    use iced_native::widget::text_input::{self, TextInput};
+    use iced_native::widget::{Row, Text};
+    use iced_native::{Element, Length};
+
+    pub struct NumericInput<'a, Message> {
+        state: &'a mut State,
+        value: Option<u32>,
+        on_change: Box<dyn Fn(Option<u32>) -> Message>,
+    }
+
+    #[derive(Default)]
+    pub struct State {
+        input: text_input::State,
+        decrement_button: button::State,
+        increment_button: button::State,
+    }
+
+    #[derive(Debug, Clone)]
+    pub enum Event {
+        InputChanged(String),
+        IncrementPressed,
+        DecrementPressed,
+    }
+
+    impl<'a, Message> NumericInput<'a, Message> {
+        pub fn new(
+            state: &'a mut State,
+            value: Option<u32>,
+            on_change: impl Fn(Option<u32>) -> Message + 'static,
+        ) -> Self {
+            Self {
+                state,
+                value,
+                on_change: Box::new(on_change),
+            }
+        }
+    }
+
+    impl<'a, Message, Renderer> Component<Message, Renderer>
+        for NumericInput<'a, Message>
+    where
+        Renderer: 'a + text::Renderer,
+    {
+        type Event = Event;
+
+        fn update(&mut self, event: Event) -> Option<Message> {
+            match event {
+                Event::IncrementPressed => Some((self.on_change)(Some(
+                    self.value.unwrap_or_default().saturating_add(1),
+                ))),
+                Event::DecrementPressed => Some((self.on_change)(Some(
+                    self.value.unwrap_or_default().saturating_sub(1),
+                ))),
+                Event::InputChanged(value) => {
+                    if value.is_empty() {
+                        Some((self.on_change)(None))
+                    } else {
+                        value
+                            .parse()
+                            .ok()
+                            .map(Some)
+                            .map(self.on_change.as_ref())
+                    }
+                }
+            }
+        }
+
+        fn view(&mut self) -> Element<Event, Renderer> {
+            let button = |state, label, on_press| {
+                Button::new(
+                    state,
+                    Text::new(label)
+                        .width(Length::Fill)
+                        .height(Length::Fill)
+                        .horizontal_alignment(alignment::Horizontal::Center)
+                        .vertical_alignment(alignment::Vertical::Center),
+                )
+                .width(Length::Units(50))
+                .on_press(on_press)
+            };
+
+            Row::with_children(vec![
+                button(
+                    &mut self.state.decrement_button,
+                    "-",
+                    Event::DecrementPressed,
+                )
+                .into(),
+                TextInput::new(
+                    &mut self.state.input,
+                    "Type a number",
+                    self.value
+                        .as_ref()
+                        .map(u32::to_string)
+                        .as_ref()
+                        .map(String::as_str)
+                        .unwrap_or(""),
+                    Event::InputChanged,
+                )
+                .padding(10)
+                .into(),
+                button(
+                    &mut self.state.increment_button,
+                    "+",
+                    Event::IncrementPressed,
+                )
+                .into(),
+            ])
+            .align_items(Alignment::Fill)
+            .spacing(10)
+            .into()
+        }
+    }
+
+    impl<'a, Message, Renderer> From<NumericInput<'a, Message>>
+        for Element<'a, Message, Renderer>
+    where
+        Message: 'a,
+        Renderer: text::Renderer + 'a,
+    {
+        fn from(numeric_input: NumericInput<'a, Message>) -> Self {
+            component::view(Box::new(numeric_input))
+        }
+    }
+}