Adapt to iced pure (stateless widgets)

Signed-off-by: fab <fab@pop-os.localdomain>

src/calendar.rs

@@ -13,7 +13,7 @@ use iced_native::renderer;
 use iced_native::{Color, Element, Length, Point, Rectangle, Size, Widget};
 use iced_native::text;
 use iced_native::alignment;
-
+use iced_native::widget::Tree;
 
 //-------------------------------------------------------------------------
 
@@ -262,6 +262,7 @@ where
 
     fn draw(
         &self,
+        _state: &Tree,
         renderer: &mut Renderer,
         _theme: &Renderer::Theme,
         _style: &renderer::Style,

src/main.rs

@@ -4,11 +4,15 @@ mod calendar;
 use calendar::{CalendarMonthView, CalendarParams };
 
 use iced::{
-    Alignment, Column, Row,
-    Container, Element, Length, Sandbox, Settings,
+    Alignment,
+    Element, Length, Sandbox, Settings,
+};
+use iced::widget::{
+    Column, Row,
+    Container,
     Button, Text,
 };
-use iced::button;
+//use iced::button;
 use iced::theme;
 
 pub fn main() -> iced::Result {
@@ -29,28 +33,27 @@ enum Message {
 
 #[derive(Default)]
 struct Controls {
-    prev_button: button::State,
-    next_button: button::State,
 }
 
 impl Controls {
-    fn view(&mut self, month_name: &str) -> Element<Message> {
+    fn view(&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("<<"))
+                Button::new(Text::new("<<"))
                 .on_press(Message::PrevMonth)
                 .style(theme::Button::Secondary),
             )
             .push(
                 Text::new(month_name)
-                    .width(Length::Shrink)
+                    .width(Length::Fill)
+                    .horizontal_alignment(iced_native::alignment::Horizontal::Center)
                     .size(50),
             )
             .push(
-                Button::new(&mut self.next_button, Text::new(">>"))
+                Button::new(Text::new(">>"))
                     .on_press(Message::NextMonth)
                     .style(theme::Button::Secondary),
             )
@@ -84,7 +87,7 @@ impl Sandbox for CalendarApp {
         println!("month={}", self.month);
     }
 
-    fn view(&mut self) -> Element<Message> {
+    fn view(&self) -> Element<Message> {
         const MONTH_NAMES: [&str;12] = [
             "January",
             "February",
@@ -96,7 +99,7 @@ impl Sandbox for CalendarApp {
             "August",
             "September",
             "October",
-            "Novemeber",
+            "November",
             "December",
         ];
         let content = Column::new()