Merge pull request #1400 from nicksenger/lazy/cached

`Lazy` widget

Cargo.toml

@@ -72,6 +72,7 @@ members = [
     "examples/geometry",
     "examples/integration_opengl",
     "examples/integration_wgpu",
+    "examples/lazy",
     "examples/multitouch",
     "examples/pane_grid",
     "examples/pick_list",

examples/cached/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "cached"
+version = "0.1.0"
+authors = ["Nick Senger <[email protected]>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../..", features = ["debug"] }
+iced_lazy = { path = "../../lazy" }

examples/cached/src/main.rs

@@ -0,0 +1,139 @@
+use iced::theme;
+use iced::widget::{
+    button, column, horizontal_space, row, scrollable, text, text_input,
+};
+use iced::{Element, Length, Sandbox, Settings};
+use iced_lazy::lazy;
+
+use std::collections::HashSet;
+
+pub fn main() -> iced::Result {
+    App::run(Settings::default())
+}
+
+struct App {
+    options: HashSet<String>,
+    input: String,
+    order: Order,
+}
+
+impl Default for App {
+    fn default() -> Self {
+        Self {
+            options: ["Foo", "Bar", "Baz", "Qux", "Corge", "Waldo", "Fred"]
+                .into_iter()
+                .map(ToString::to_string)
+                .collect(),
+            input: Default::default(),
+            order: Order::Ascending,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+enum Message {
+    InputChanged(String),
+    ToggleOrder,
+    DeleteOption(String),
+    AddOption(String),
+}
+
+impl Sandbox for App {
+    type Message = Message;
+
+    fn new() -> Self {
+        Self::default()
+    }
+
+    fn title(&self) -> String {
+        String::from("Cached - Iced")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::InputChanged(input) => {
+                self.input = input;
+            }
+            Message::ToggleOrder => {
+                self.order = match self.order {
+                    Order::Ascending => Order::Descending,
+                    Order::Descending => Order::Ascending,
+                }
+            }
+            Message::AddOption(option) => {
+                self.options.insert(option);
+                self.input.clear();
+            }
+            Message::DeleteOption(option) => {
+                self.options.remove(&option);
+            }
+        }
+    }
+
+    fn view(&self) -> Element<Message> {
+        let options = lazy((&self.order, self.options.len()), || {
+            let mut options: Vec<_> = self.options.iter().collect();
+
+            options.sort_by(|a, b| match self.order {
+                Order::Ascending => a.to_lowercase().cmp(&b.to_lowercase()),
+                Order::Descending => b.to_lowercase().cmp(&a.to_lowercase()),
+            });
+
+            column(
+                options
+                    .into_iter()
+                    .map(|option| {
+                        row![
+                            text(option),
+                            horizontal_space(Length::Fill),
+                            button("Delete")
+                                .on_press(Message::DeleteOption(
+                                    option.to_string(),
+                                ),)
+                                .style(theme::Button::Destructive)
+                        ]
+                        .into()
+                    })
+                    .collect(),
+            )
+            .spacing(10)
+        });
+
+        column![
+            scrollable(options).height(Length::Fill),
+            row![
+                text_input(
+                    "Add a new option",
+                    &self.input,
+                    Message::InputChanged,
+                )
+                .on_submit(Message::AddOption(self.input.clone())),
+                button(text(format!("Toggle Order ({})", self.order)))
+                    .on_press(Message::ToggleOrder)
+            ]
+            .spacing(10)
+        ]
+        .spacing(20)
+        .padding(20)
+        .into()
+    }
+}
+
+#[derive(Debug, Hash)]
+enum Order {
+    Ascending,
+    Descending,
+}
+
+impl std::fmt::Display for Order {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                Self::Ascending => "Ascending",
+                Self::Descending => "Descending",
+            }
+        )
+    }
+}

examples/lazy/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "lazy"
+version = "0.1.0"
+authors = ["Nick Senger <[email protected]>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+iced = { path = "../..", features = ["debug"] }
+iced_lazy = { path = "../../lazy" }

examples/lazy/src/main.rs

@@ -0,0 +1,139 @@
+use iced::theme;
+use iced::widget::{
+    button, column, horizontal_space, row, scrollable, text, text_input,
+};
+use iced::{Element, Length, Sandbox, Settings};
+use iced_lazy::lazy;
+
+use std::collections::HashSet;
+
+pub fn main() -> iced::Result {
+    App::run(Settings::default())
+}
+
+struct App {
+    options: HashSet<String>,
+    input: String,
+    order: Order,
+}
+
+impl Default for App {
+    fn default() -> Self {
+        Self {
+            options: ["Foo", "Bar", "Baz", "Qux", "Corge", "Waldo", "Fred"]
+                .into_iter()
+                .map(ToString::to_string)
+                .collect(),
+            input: Default::default(),
+            order: Order::Ascending,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+enum Message {
+    InputChanged(String),
+    ToggleOrder,
+    DeleteOption(String),
+    AddOption(String),
+}
+
+impl Sandbox for App {
+    type Message = Message;
+
+    fn new() -> Self {
+        Self::default()
+    }
+
+    fn title(&self) -> String {
+        String::from("Cached - Iced")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::InputChanged(input) => {
+                self.input = input;
+            }
+            Message::ToggleOrder => {
+                self.order = match self.order {
+                    Order::Ascending => Order::Descending,
+                    Order::Descending => Order::Ascending,
+                }
+            }
+            Message::AddOption(option) => {
+                self.options.insert(option);
+                self.input.clear();
+            }
+            Message::DeleteOption(option) => {
+                self.options.remove(&option);
+            }
+        }
+    }
+
+    fn view(&self) -> Element<Message> {
+        let options = lazy((&self.order, self.options.len()), || {
+            let mut options: Vec<_> = self.options.iter().collect();
+
+            options.sort_by(|a, b| match self.order {
+                Order::Ascending => a.to_lowercase().cmp(&b.to_lowercase()),
+                Order::Descending => b.to_lowercase().cmp(&a.to_lowercase()),
+            });
+
+            column(
+                options
+                    .into_iter()
+                    .map(|option| {
+                        row![
+                            text(option),
+                            horizontal_space(Length::Fill),
+                            button("Delete")
+                                .on_press(Message::DeleteOption(
+                                    option.to_string(),
+                                ),)
+                                .style(theme::Button::Destructive)
+                        ]
+                        .into()
+                    })
+                    .collect(),
+            )
+            .spacing(10)
+        });
+
+        column![
+            scrollable(options).height(Length::Fill),
+            row![
+                text_input(
+                    "Add a new option",
+                    &self.input,
+                    Message::InputChanged,
+                )
+                .on_submit(Message::AddOption(self.input.clone())),
+                button(text(format!("Toggle Order ({})", self.order)))
+                    .on_press(Message::ToggleOrder)
+            ]
+            .spacing(10)
+        ]
+        .spacing(20)
+        .padding(20)
+        .into()
+    }
+}
+
+#[derive(Debug, Hash)]
+enum Order {
+    Ascending,
+    Descending,
+}
+
+impl std::fmt::Display for Order {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                Self::Ascending => "Ascending",
+                Self::Descending => "Descending",
+            }
+        )
+    }
+}