refactor: apply clippy lints

cargo clippy --no-deps -- --deny clippy::nursery --deny clippy::pedantic
(does not quite pass due to unused `&self` in State::subscription)
I am considering ignoring events when the file picker is opened,
but that isn't a very nice solution (should just make it async atp)

src/main.rs

@@ -29,7 +29,7 @@ struct State {
 }
 impl State {
     fn new() -> (Self, Task<Message>) {
-        let mut state = State::default();
+        let mut state = Self::default();
 
         if let Some(path) = env::args().nth(1) {
             match state.load_image(path) {
@@ -43,7 +43,16 @@ impl State {
     fn view(&self) -> Element<'_, Message, Theme, Renderer> {
         let mut main = Vec::new();
 
-        main.push(if let Some(allocation) = self.image_display.as_ref() {
+        main.push(self.image_display.as_ref().map_or_else(
+            || {
+                widget::container(widget::text(include_str!("usage.txt")))
+                    .height(Length::Fill)
+                    .width(Length::Fill)
+                    .align_x(Alignment::Center)
+                    .align_y(Alignment::Center)
+                    .into()
+            },
+            |allocation| {
                 widget::image::viewer(allocation.handle().clone())
                     .filter_method(self.image_filter)
                     .max_scale(50.)
@@ -51,14 +60,8 @@ impl State {
                     .width(Length::Fill)
                     .height(Length::Fill)
                     .into()
-        } else {
+            },
-            widget::container(widget::text(include_str!("usage.txt")))
+        ));
-                .height(Length::Fill)
-                .width(Length::Fill)
-                .align_x(Alignment::Center)
-                .align_y(Alignment::Center)
-                .into()
-        });
 
         if let Some(error) = self.error.as_ref() {
             main.push(widget::text(error).style(widget::text::danger).into());
@@ -84,9 +87,8 @@ impl State {
                 Key::Named(key::Named::Tab) => {
                     if modifiers.shift() {
                         return widget::operation::focus_previous();
-                    } else {
-                        return widget::operation::focus_next();
                     }
+                    return widget::operation::focus_next();
                 }
 
                 Key::Character("o") => match self.pick_and_load_image() {
@@ -97,26 +99,22 @@ impl State {
                     Err(e) => self.error = Some(e),
                 },
 
-                Key::Character("r") => {
+                Key::Character("r") => match self.image.as_ref() {
-                    match self.image.as_ref() {
                     None => self.error = Some("no image to rotate".into()),
                     Some(image) => {
                         self.error = None;
                         self.image = Some(imageops::rotate90(image));
                         return self.allocate_image();
                     }
-                    };
+                },
-                }
+                Key::Character("i") => match self.image.as_mut() {
-                Key::Character("i") => {
-                    match self.image.as_mut() {
                     None => self.error = Some("no image to invert".into()),
                     Some(image) => {
                         self.error = None;
                         imageops::invert(image);
                         return self.allocate_image();
                     }
-                    };
+                },
-                }
                 Key::Character("f") => {
                     self.image_filter = match self.image_filter {
                         widget::image::FilterMethod::Linear => widget::image::FilterMethod::Nearest,
@@ -160,8 +158,7 @@ impl State {
                 "{} {}x{}",
                 path.as_ref()
                     .file_name()
-                    .map(OsStr::to_string_lossy)
+                    .map_or(Cow::Borrowed("[no file]"), OsStr::to_string_lossy),
-                    .unwrap_or(Cow::Borrowed("[no file]")),
                 image.width(),
                 image.height(),
             ));
@@ -210,13 +207,15 @@ impl State {
         event::listen().map(Message::Event)
     }
     fn title(&self) -> String {
-        match self.info.as_ref() {
+        self.info.as_ref().map_or_else(
-            Some(info) => format!(
+            || "imagey".into(),
+            |info| {
+                format!(
                     "imagey {info} {}",
                     utils::string_from_filter_type(self.image_filter),
-            ),
+                )
-            None => "imagey".into(),
+            },
-        }
+        )
     }
 }
 

src/utils.rs

@@ -5,9 +5,9 @@ use image::{DynamicImage, ImageDecoder, ImageReader, ImageResult, RgbaImage};
 use rfd::FileDialog;
 
 pub fn load_image(path: impl AsRef<Path>) -> Result<RgbaImage, String> {
-    _load_image(path).map_err(|e| e.to_string())
+    load_image_impl(path).map_err(|e| e.to_string())
 }
-fn _load_image(path: impl AsRef<Path>) -> ImageResult<RgbaImage> {
+fn load_image_impl(path: impl AsRef<Path>) -> ImageResult<RgbaImage> {
     let mut decoder = ImageReader::open(path)?
         .with_guessed_format()?
         .into_decoder()?;
@@ -48,12 +48,12 @@ pub fn save_image(image: Option<&RgbaImage>) -> Result<(), String> {
 
     if let Err(e) = image.save(&path) {
         return Err(e.to_string());
-    };
+    }
 
     Ok(())
 }
 
-pub fn string_from_filter_type(f: widget::image::FilterMethod) -> &'static str {
+pub const fn string_from_filter_type(f: widget::image::FilterMethod) -> &'static str {
     match f {
         widget::image::FilterMethod::Linear => "bilinear",
         widget::image::FilterMethod::Nearest => "nearest neighbor",