First version of calendar app

- Monthly View
- prev/next month buttons
- year hard-coded to 2022

Signed-off-by: Fabrizio Iannetti <fabrizio.iannetti@gmail.com>

.gitignore

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+/target

.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>calendar</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+	</buildSpec>
+	<natures>
+	</natures>
+</projectDescription>

Cargo.toml

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+[package]
+name = "calendar"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+#iced = "0.4.2"
+#iced_native = "0.5.1"
+iced = { path = "../iced" }
+iced_native = { path = "../iced/native" }

src/calendar.rs

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+// For now, to implement a custom native widget you will need to add
+// `iced_native` and `iced_wgpu` to your dependencies.
+//
+// Then, you simply need to define your widget type and implement the
+// `iced_native::Widget` trait with the `iced_wgpu::Renderer`.
+//
+// Of course, you can choose to make the implementation renderer-agnostic,
+// if you wish to, by creating your own `Renderer` trait, which could be
+// implemented by `iced_wgpu` and other renderers.
+
+use iced_native::layout::{self, Layout};
+use iced_native::renderer;
+use iced_native::{Color, Element, Length, Point, Rectangle, Size, Widget};
+use iced_native::text;
+use iced_native::alignment;
+
+
+//-------------------------------------------------------------------------
+
+const DAYS_PER_MONTH: [i32;12] = [
+    31, // jan
+    28, // feb
+    31, // mar
+    30, // apr
+    31, // may
+    30, // jun
+    31, // jul
+    31, // ago
+    30, // sep
+    31, // oct
+    30, // nov
+    31, // dec
+];
+
+#[derive(Clone)]
+pub struct CalendarParams {
+    weekday_on_first_of_january: i32, // 0 -> Monday .. 6 -> Sunday
+    first_week_on_first_of_january: bool,
+    leap_year: bool,
+}
+
+impl CalendarParams {
+    pub fn new() -> Self {
+        // temp: data for 2022
+        Self {
+            weekday_on_first_of_january: 5, // saturday
+            first_week_on_first_of_january: false,
+            leap_year: false
+        }
+    }
+
+    pub fn day_first_of_month(&self, month: i32) -> i32 {
+        let mut day : i32 = 0;
+        for i in 0..month {
+            day += DAYS_PER_MONTH[i as usize];
+            if i == 1 && self.leap_year {
+                day += 1;
+            }
+        }
+        day
+    }
+
+    pub fn monthday(&self, month: i32, day: i32) -> i32 {
+        let mut month_days: i32 = DAYS_PER_MONTH[month as usize];
+        let mut month: i32 = month;
+        let mut day: i32 = day;
+        while day < 0 || day >= month_days {
+            if day < 0 {
+                month = (month + 12 - 1) % 12;
+                day = day + DAYS_PER_MONTH[month as usize];
+            } else {
+                day = day - DAYS_PER_MONTH[month as usize];
+                month = (month + 1) % 12;
+            }
+            month_days = DAYS_PER_MONTH[month as usize];
+        }
+        day
+    }
+
+    pub fn weekday(&self, month: i32, day: i32) -> i32 {
+        let day = self.day_first_of_month(month) + day;
+        (self.weekday_on_first_of_january + day) % 7
+    }
+
+    pub fn weekday_first_of_month(&self, month: i32) -> i32 {
+        self.weekday(month, 0)
+    }
+}
+//-------------------------------------------------------------------------
+
+pub struct CalendarMonthView {
+    month: i32,
+    params: CalendarParams,
+    weekday_on_first: i32, // 0 -> Monday .. 6 -> Sunday
+    header_fg: Color,
+    header_bg: Color,
+    day_text: Color,
+    day_text_other_month: Color,
+    day_weekend_bg: Color,
+}
+
+impl CalendarMonthView {
+    pub fn new(params: &CalendarParams, month: i32) -> Self {
+        Self { 
+            month,
+            params: params.clone(),
+            weekday_on_first: params.weekday_first_of_month(month), 
+            header_fg: Color::BLACK,
+            header_bg: Color::from_rgb8(214, 242, 252),
+            day_text: Color::BLACK,
+            day_text_other_month: Color::from_rgb8(220, 220, 220),
+//            day_background: Color::from_rgb8(230, 230, 255),
+            day_weekend_bg: Color::from_rgb8(250, 250, 250),
+        }
+    }
+
+    pub fn set_month(&mut self, month: i32) {
+        self.month = month;
+        self.weekday_on_first = self.params.weekday_first_of_month(month);
+    }
+
+    fn draw_header(
+        &self,
+        renderer: &mut impl text::Renderer,
+        bounds: Rectangle,
+    ) {
+        let origin = bounds.position();
+
+        // font dimension
+        let font_size = renderer.default_size() as f32;
+
+        // dimensions of each box representing a day
+        let w: f32 = bounds.width / 7.0;
+        let h: f32 = bounds.height;
+
+        let days_of_week = ["Lun", "Mar", "Mer", "Gio", "Ven", "Sab", "Dom"];
+
+        renderer.fill_quad(renderer::Quad {
+                bounds,
+                border_radius: 0.0,
+                border_width: 0.0,
+                border_color: Color::TRANSPARENT,
+            }, 
+            self.header_bg);
+        
+        for weekday in 0..7i32 {
+            let bounds = Rectangle { 
+                x: (weekday as f32) * w + origin.x,
+                y: origin.y,
+                width: w,
+                height: h
+            };
+                    
+            // label (day letter on row 0, day number on the rest)
+            let t =  days_of_week[weekday as usize];
+
+            // color of text
+            let fg = self.header_fg;
+
+            let x = bounds.center_x();
+            let y = bounds.center_y();
+            renderer.fill_text(text::Text {
+                content : t,
+                size: font_size,
+                bounds: Rectangle {x, y, ..bounds},
+                color: fg,
+                font: Default::default(),
+                horizontal_alignment: alignment::Horizontal::Center,
+                vertical_alignment: alignment::Vertical::Center,
+                });
+        }
+    }
+
+    fn draw_days(
+        &self,
+        renderer: &mut impl text::Renderer,
+        bounds: Rectangle,
+    ) {
+        let size: Size = bounds.size();
+        let origin = bounds.position();
+
+        // font dimension
+        let font_size = renderer.default_size() as f32;
+
+        // dimensions of each box representing a day
+        let w: f32 = size.width / 7.0;
+        let h: f32 = size.height / 6.0;
+
+        let days_of_month = [
+            " 1", " 2", " 3", " 4", " 5", " 6", " 7", " 8", " 9", "10",
+            "11", "12", "13", "14", "15", "16", "17", "18", "19", "20",
+            "21", "22", "23", "24", "25", "26", "27", "28", "29", "30",
+            "31",
+            ];
+
+        // paint the background of the last two columns as weekend
+        renderer.fill_quad(renderer::Quad {
+                bounds: Rectangle {x: 5.0 * w + origin.x, y: origin.y, width: 2.0 * w, height: 6.0 * h},
+                border_radius: 0.0,
+                border_width: 0.0,
+                border_color: Color::TRANSPARENT,
+            }, 
+            self.day_weekend_bg);
+
+        for week in 0..6i32 {
+            for weekday in 0..7i32 {
+                let monthday = weekday + week * 7 - self.weekday_on_first;
+                let day_bounds = Rectangle { 
+                    x: (weekday as f32) * (w + 2.0) + origin.x, 
+                    y: (week as f32) * (h + 2.0) + origin.y, 
+                    width: w, 
+                    height: h 
+                };
+                        
+                // label (day letter on row 0, day number on the rest)
+                let t = days_of_month[self.params.monthday(self.month, monthday) as usize];
+
+                // color of text
+                let fg = if monthday >= 0 && monthday <= 30 {
+                    self.day_text
+                } else {
+                    self.day_text_other_month
+                };
+
+                let x = day_bounds.center_x();
+                let y = day_bounds.center_y();
+                
+                renderer.fill_text(text::Text {
+                    content : t,
+                    size: font_size,
+                    bounds: Rectangle {x, y, ..day_bounds},
+                    color: fg,
+                    font: Default::default(),
+                    horizontal_alignment: alignment::Horizontal::Center,
+                    vertical_alignment: alignment::Vertical::Center,
+                    });
+            }
+        }
+    }
+
+} // CalendarMonthView
+
+impl<Message, Renderer> Widget<Message, Renderer> for CalendarMonthView
+where
+    Renderer: text::Renderer,
+{
+    fn width(&self) -> Length {
+        Length::Shrink
+    }
+
+    fn height(&self) -> Length {
+        Length::Shrink
+    }
+
+    fn layout(
+        &self,
+        _renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        layout::Node::new(limits.max())
+    }
+
+    fn draw(
+        &self,
+        renderer: &mut Renderer,
+        _theme: &Renderer::Theme,
+        _style: &renderer::Style,
+        layout: Layout<'_>,
+        _cursor_position: Point,
+        _viewport: &Rectangle,
+    ) {
+        let size: Size = layout.bounds().size();
+        let origin = layout.bounds().position();
+        let margin: f32 = 20.0;
+
+        // font and header dimension
+        let font_size = renderer.default_size() as f32;
+        let first_row_h = font_size + margin;
+
+        // header
+        let x = origin.x;
+        let y = origin.y;
+        let width = size.width;
+        let height = first_row_h;
+        self.draw_header(renderer, Rectangle {x, y, width, height});
+
+        // monthly calendar cells
+        let x = origin.x;
+        let y = origin.y + first_row_h;
+        let width = size.width;
+        let height = size.height - first_row_h;
+        self.draw_days(renderer, Rectangle{x, y, width, height});
+    }
+}
+
+impl<'a, Message, Renderer> From<CalendarMonthView> for Element<'a, Message, Renderer>
+where
+    Renderer: text::Renderer,
+{
+    fn from(circle: CalendarMonthView) -> Self {
+        Self::new(circle)
+    }
+}

src/main.rs

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+//! Simple calendar applications.
+mod calendar;
+
+use calendar::{CalendarMonthView, CalendarParams };
+
+use iced::{
+    Alignment, Column, Row,
+    Container, Element, Length, Sandbox, Settings,
+    Button, Text,
+};
+use iced::button;
+use iced::theme;
+
+pub fn main() -> iced::Result {
+    CalendarApp::run(Settings::default())
+}
+
+#[derive(Default)]
+struct CalendarApp {
+    month: i32,
+    controls: Controls,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum Message {
+    NextMonth,
+    PrevMonth,
+}
+
+#[derive(Default)]
+struct Controls {
+    prev_button: button::State,
+    next_button: button::State,
+}
+
+impl Controls {
+    fn view(&mut self, month_name: &str) -> Element<Message> {
+        Row::new()
+            .align_items(Alignment::Center)
+            .padding(5)
+            .spacing(10)
+            .push(
+                Button::new(&mut self.prev_button, Text::new("<<"))
+                .on_press(Message::PrevMonth)
+                .style(theme::Button::Secondary),
+            )
+            .push(
+                Text::new(month_name)
+                    .width(Length::Shrink)
+                    .size(50),
+            )
+            .push(
+                Button::new(&mut self.next_button, Text::new(">>"))
+                    .on_press(Message::NextMonth)
+                    .style(theme::Button::Secondary),
+            )
+            .into()
+    }
+}
+
+impl Sandbox for CalendarApp {
+    type Message = Message;
+
+    fn new() -> Self {
+        CalendarApp {
+            month: 7,
+            ..CalendarApp::default()
+        }
+    }
+
+    fn title(&self) -> String {
+        String::from("Calendar")
+    }
+
+    fn update(&mut self, message: Message) {
+        match message {
+            Message::PrevMonth => {
+                self.month = (self.month + 12 - 1) % 12;
+            }
+            Message::NextMonth => {
+                self.month = (self.month + 12 + 1) % 12;
+            }
+        }
+        println!("month={}", self.month);
+    }
+
+    fn view(&mut self) -> Element<Message> {
+        const MONTH_NAMES: [&str;12] = [
+            "January",
+            "February",
+            "March",
+            "April",
+            "May",
+            "June",
+            "July",
+            "August",
+            "September",
+            "October",
+            "Novemeber",
+            "December",
+        ];
+        let content = Column::new()
+            .align_items(Alignment::Fill)
+            .push(self.controls.view(MONTH_NAMES[self.month as usize]))
+            .push(CalendarMonthView::new(&CalendarParams::new(), self.month))
+            ;
+
+//        let area = Row::new()
+//            .align_items(Alignment::Fill)
+//            .push(Column::new()
+//                .align_items(Alignment::Start)
+//                .push(CalendarMonthView::new(6))
+//                .push(CalendarMonthView::new(6))
+//            )
+//            .push(content)
+//            ;
+        Container::new(content)
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .center_x()
+            .center_y()
+            .into()
+    }
+}