dioxus/examples/pattern_model.rs

//! Example: Calculator
//! -------------------
//!
//! Some components benefit through the use of "Models". Models are a single block of encapsulated state that allow mutative
//! methods to be performed on them. Dioxus exposes the ability to use the model pattern through the "use_model" hook.
//!
//! Models are commonly used in the "Model-View-Component" approach for building UI state.
//!
//! `use_model` is basically just a fancy wrapper around set_state, but saves a "working copy" of the new state behind a
//! RefCell. To modify the working copy, you need to call "get_mut" which returns the RefMut. This makes it easy to write
//! fully encapsulated apps that retain a certain feel of native Rusty-ness. A calculator app is a good example of when this
//! is useful.
//!
//! Do note that "get_mut" returns a `RefMut` (a lock over a RefCell). If two `RefMut`s are held at the same time (ie in a loop)
//! the RefCell will panic and crash. You can use `try_get_mut` or `.modify` to avoid this problem, or just not hold two
//! RefMuts at the same time.

use dioxus::desktop::wry::application::dpi::LogicalSize;
use dioxus::events::*;
use dioxus::prelude::*;

fn main() {
    dioxus::desktop::launch_cfg(app, |cfg| {
        cfg.with_window(|w| {
            w.with_title("Calculator Demo")
                .with_resizable(false)
                .with_inner_size(LogicalSize::new(320.0, 530.0))
        })
    });
}

fn app(cx: Scope) -> Element {
    let state = use_ref(&cx, || Calculator::new());

    cx.render(rsx! {
        style { [include_str!("./assets/calculator.css")] }
        div { id: "wrapper",
            div { class: "app",
                div { class: "calculator", onkeypress: move |evt| state.write().handle_keydown(evt),
                    div { class: "calculator-display", [state.read().formatted_display()]}
                    div { class: "calculator-keypad",
                        div { class: "input-keys",
                            div { class: "function-keys",
                                CalculatorKey {
                                    name: "key-clear",
                                    onclick: move |_| state.write().clear_display(),
                                    [if state.read().display_value == "0" { "C" } else { "AC" }]
                                }
                                CalculatorKey {
                                    name: "key-sign",
                                    onclick: move |_| state.write().toggle_sign(),
                                    "±"
                                }
                                CalculatorKey {
                                    name: "key-percent",
                                    onclick: move |_| state.write().toggle_percent(),
                                    "%"
                                }
                            }
                            div { class: "digit-keys",
                                CalculatorKey {
                                    name: "key-0",
                                    onclick: move |_| state.write().input_digit(0),
                                    "0"
                                }
                                CalculatorKey {
                                    name: "key-dot",
                                    onclick: move |_|  state.write().input_dot(),
                                    "●"
                                }
                                (1..10).map(move |k| rsx!{
                                    CalculatorKey {
                                        key: "{k}",
                                        name: "key-{k}",
                                        onclick: move |_| state.write().input_digit(k),
                                        "{k}"
                                    }
                                })
                            }
                        }
                        div { class: "operator-keys",
                            CalculatorKey {
                                name: "key-divide",
                                onclick: move |_| state.write().set_operator(Operator::Div),
                                "÷"
                            }
                            CalculatorKey {
                                name: "key-multiply",
                                onclick: move |_| state.write().set_operator(Operator::Mul),
                                "×"
                            }
                            CalculatorKey {
                                name: "key-subtract",
                                onclick: move |_| state.write().set_operator(Operator::Sub),
                                "−"
                            }
                            CalculatorKey {
                                name: "key-add",
                                onclick: move |_| state.write().set_operator(Operator::Add),
                                "+"
                            }
                            CalculatorKey {
                                name: "key-equals",
                                onclick: move |_| state.write().perform_operation(),
                                "="
                            }
                        }
                    }
                }
            }
        }
    })
}

#[derive(Props)]
struct CalculatorKeyProps<'a> {
    name: &'a str,
    onclick: EventHandler<'a, MouseEvent>,
    children: Element<'a>,
}

fn CalculatorKey<'a>(cx: Scope<'a, CalculatorKeyProps<'a>>) -> Element {
    cx.render(rsx! {
        button {
            class: "calculator-key {cx.props.name}",
            onclick: move |e| cx.props.onclick.call(e),
            &cx.props.children
        }
    })
}

struct Calculator {
    display_value: String,
    operator: Option<Operator>,
    waiting_for_operand: bool,
    cur_val: f64,
}
#[derive(Clone)]
enum Operator {
    Add,
    Sub,
    Mul,
    Div,
}
impl Calculator {
    fn new() -> Self {
        Calculator {
            display_value: "0".to_string(),
            operator: None,
            waiting_for_operand: false,
            cur_val: 0.0,
        }
    }
    fn formatted_display(&self) -> String {
        use separator::Separatable;
        self.display_value
            .parse::<f64>()
            .unwrap()
            .separated_string()
    }
    fn clear_display(&mut self) {
        self.display_value = "0".to_string();
    }
    fn input_digit(&mut self, digit: u8) {
        let content = digit.to_string();
        if self.waiting_for_operand || self.display_value == "0" {
            self.waiting_for_operand = false;
            self.display_value = content;
        } else {
            self.display_value.push_str(content.as_str());
        }
    }
    fn input_dot(&mut self) {
        if self.display_value.find(".").is_none() {
            self.display_value.push_str(".");
        }
    }
    fn perform_operation(&mut self) {
        if let Some(op) = &self.operator {
            let rhs = self.display_value.parse::<f64>().unwrap();
            let new_val = match op {
                Operator::Add => self.cur_val + rhs,
                Operator::Sub => self.cur_val - rhs,
                Operator::Mul => self.cur_val * rhs,
                Operator::Div => self.cur_val / rhs,
            };
            self.cur_val = new_val;
            self.display_value = new_val.to_string();
            self.operator = None;
        }
    }
    fn toggle_sign(&mut self) {
        if self.display_value.starts_with("-") {
            self.display_value = self.display_value.trim_start_matches("-").to_string();
        } else {
            self.display_value = format!("-{}", self.display_value);
        }
    }
    fn toggle_percent(&mut self) {
        self.display_value = (self.display_value.parse::<f64>().unwrap() / 100.0).to_string();
    }
    fn backspace(&mut self) {
        if !self.display_value.as_str().eq("0") {
            self.display_value.pop();
        }
    }
    fn set_operator(&mut self, operator: Operator) {
        self.operator = Some(operator);
        self.cur_val = self.display_value.parse::<f64>().unwrap();
        self.waiting_for_operand = true;
    }
    fn handle_keydown(&mut self, evt: KeyboardEvent) {
        match evt.key_code {
            KeyCode::Backspace => self.backspace(),
            KeyCode::Num0 => self.input_digit(0),
            KeyCode::Num1 => self.input_digit(1),
            KeyCode::Num2 => self.input_digit(2),
            KeyCode::Num3 => self.input_digit(3),
            KeyCode::Num4 => self.input_digit(4),
            KeyCode::Num5 => self.input_digit(5),
            KeyCode::Num6 => self.input_digit(6),
            KeyCode::Num7 => self.input_digit(7),
            KeyCode::Num8 => self.input_digit(8),
            KeyCode::Num9 => self.input_digit(9),
            KeyCode::Add => self.operator = Some(Operator::Add),
            KeyCode::Subtract => self.operator = Some(Operator::Sub),
            KeyCode::Divide => self.operator = Some(Operator::Div),
            KeyCode::Multiply => self.operator = Some(Operator::Mul),
            _ => {}
        }
    }
}