Write documentation for `iced_core`

16 files changed, 216 insertions, 44 deletions

diff --git a/core/src/background.rs b/core/src/background.rs
index 59b67a2c..98047172 100644
--- a/core/src/background.rs
+++ b/core/src/background.rs
@@ -1,7 +1,9 @@
 use crate::Color;
 
+/// The background of some element.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum Background {
+    /// A solid color
     Color(Color),
     // TODO: Add gradient and image variants
 }
diff --git a/core/src/color.rs b/core/src/color.rs
index 150bd05b..ec48c185 100644
--- a/core/src/color.rs
+++ b/core/src/color.rs
@@ -25,6 +25,9 @@ impl Color {
         a: 1.0,
     };
 
+    /// Converts the [`Color`] into its linear values.
+    ///
+    /// [`Color`]: struct.Color.html
     pub fn into_linear(self) -> [f32; 4] {
         // As described in:
         // https://en.wikipedia.org/wiki/SRGB#The_reverse_transformation
diff --git a/core/src/command.rs b/core/src/command.rs
index e1c865dd..698105aa 100644
--- a/core/src/command.rs
+++ b/core/src/command.rs
@@ -1,16 +1,30 @@
 use futures::future::{BoxFuture, Future, FutureExt};
 
+/// A collection of async operations.
+///
+/// You should be able to turn a future easily into a [`Command`], eiter by
+/// using the `From` trait or [`Command::perform`].
+///
+/// [`Command`]: struct.Command.html
 pub struct Command<T> {
     futures: Vec<BoxFuture<'static, T>>,
 }
 
 impl<T> Command<T> {
+    /// Creates an empty [`Command`].
+    ///
+    /// In other words, a [`Command`] that does nothing.
+    ///
+    /// [`Command`]: struct.Command.html
     pub fn none() -> Self {
         Self {
             futures: Vec::new(),
         }
     }
 
+    /// Creates a [`Command`] that performs the action of the given future.
+    ///
+    /// [`Command`]: struct.Command.html
     pub fn perform<A>(
         future: impl Future<Output = T> + 'static + Send,
         f: impl Fn(T) -> A + 'static + Send,
@@ -20,12 +34,21 @@ impl<T> Command<T> {
         }
     }
 
+    /// Creates a [`Command`] that performs the actions of all the givens
+    /// futures.
+    ///
+    /// Once this command is run, all the futures will be exectued at once.
+    ///
+    /// [`Command`]: struct.Command.html
     pub fn batch(commands: impl Iterator<Item = Command<T>>) -> Self {
         Self {
             futures: commands.flat_map(|command| command.futures).collect(),
         }
     }
 
+    /// Converts a [`Command`] into its underlying list of futures.
+    ///
+    /// [`Command`]: struct.Command.html
     pub fn futures(self) -> Vec<BoxFuture<'static, T>> {
         self.futures
     }
diff --git a/core/src/font.rs b/core/src/font.rs
index 75ba6a72..be49c825 100644
--- a/core/src/font.rs
+++ b/core/src/font.rs
@@ -1,8 +1,18 @@
+/// A font.
 #[derive(Debug, Clone, Copy)]
 pub enum Font {
+    /// The default font.
+    ///
+    /// This is normally a font configured in a renderer or loaded from the
+    /// system.
     Default,
+
+    /// An external font.
     External {
+        /// The name of the external font
         name: &'static str,
+
+        /// The bytes of the external font
         bytes: &'static [u8],
     },
 }
diff --git a/core/src/length.rs b/core/src/length.rs
index 73c227d8..63ba6207 100644
--- a/core/src/length.rs
+++ b/core/src/length.rs
@@ -1,12 +1,24 @@
 /// The strategy used to fill space in a specific dimension.
 #[derive(Debug, Clone, Copy, PartialEq, Hash)]
 pub enum Length {
+    /// Fill all the remaining space
     Fill,
+
+    /// Fill the least amount of space
     Shrink,
+
+    /// Fill a fixed amount of space
     Units(u16),
 }
 
 impl Length {
+    /// Returns the _fill factor_ of the [`Length`].
+    ///
+    /// The _fill factor_ is a relative unit describing how much of the
+    /// remaining space should be filled when compared to other elements. It
+    /// is only meant to be used by layout engines.
+    ///
+    /// [`Length`]: enum.Length.html
     pub fn fill_factor(&self) -> u16 {
         match self {
             Length::Fill => 1,
diff --git a/core/src/lib.rs b/core/src/lib.rs
index 3816f8a2..692e40d4 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -1,10 +1,22 @@
+//! The core library of [Iced].
+//!
+//! This library holds basic types that can be reused and re-exported in
+//! different runtime implementations. For instance, both [`iced_native`] and
+//! [`iced_web`] are built on top of `iced_core`.
+//!
+//! [Iced]: https://github.com/hecrj/iced
+//! [`iced_native`]: https://github.com/hecrj/iced/tree/master/native
+//! [`iced_web`]: https://github.com/hecrj/iced/tree/master/web
+#![deny(missing_docs)]
+#![deny(missing_debug_implementations)]
+#![deny(unused_results)]
+#![deny(unsafe_code)]
+#![deny(rust_2018_idioms)]
 pub mod widget;
 
 mod align;
 mod background;
 mod color;
-#[cfg(feature = "command")]
-mod command;
 mod font;
 mod length;
 mod point;
@@ -14,11 +26,15 @@ mod vector;
 pub use align::Align;
 pub use background::Background;
 pub use color::Color;
-#[cfg(feature = "command")]
-pub use command::Command;
 pub use font::Font;
 pub use length::Length;
 pub use point::Point;
 pub use rectangle::Rectangle;
 pub use vector::Vector;
 pub use widget::*;
+
+#[cfg(feature = "command")]
+mod command;
+
+#[cfg(feature = "command")]
+pub use command::Command;
diff --git a/core/src/vector.rs b/core/src/vector.rs
index 92bf64ff..7d87343a 100644
--- a/core/src/vector.rs
+++ b/core/src/vector.rs
@@ -1,7 +1,14 @@
 /// A 2D vector.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Vector<T = f32> {
+    /// The X component of the [`Vector`]
+    ///
+    /// [`Vector`]: struct.Vector.html
     pub x: T,
+
+    /// The Y component of the [`Vector`]
+    ///
+    /// [`Vector`]: struct.Vector.html
     pub y: T,
 }
 
diff --git a/core/src/widget/button.rs b/core/src/widget/button.rs
index e7961284..0ac88671 100644
--- a/core/src/widget/button.rs
+++ b/core/src/widget/button.rs
@@ -8,40 +8,22 @@
 use crate::{Background, Length};
 
 /// A generic widget that produces a message when clicked.
+#[allow(missing_docs)]
+#[derive(Debug)]
 pub struct Button<'a, Message, Element> {
-    /// The current state of the button
     pub state: &'a mut State,
-
     pub content: Element,
-
-    /// The message to produce when the button is pressed
     pub on_press: Option<Message>,
-
     pub width: Length,
-
     pub min_width: u32,
-
     pub padding: u16,
-
     pub background: Option<Background>,
-
     pub border_radius: u16,
 }
 
-impl<'a, Message, Element> std::fmt::Debug for Button<'a, Message, Element>
-where
-    Message: std::fmt::Debug,
-{
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("Button")
-            .field("state", &self.state)
-            .field("on_press", &self.on_press)
-            .finish()
-    }
-}
-
 impl<'a, Message, Element> Button<'a, Message, Element> {
-    /// Creates a new [`Button`] with some local [`State`] and the given label.
+    /// Creates a new [`Button`] with some local [`State`] and the given
+    /// content.
     ///
     /// [`Button`]: struct.Button.html
     /// [`State`]: struct.State.html
@@ -69,21 +51,34 @@ impl<'a, Message, Element> Button<'a, Message, Element> {
         self
     }
 
+    /// Sets the minimum width of the [`Button`].
+    ///
+    /// [`Button`]: struct.Button.html
     pub fn min_width(mut self, min_width: u32) -> Self {
         self.min_width = min_width;
         self
     }
 
+    /// Sets the padding of the [`Button`].
+    ///
+    /// [`Button`]: struct.Button.html
     pub fn padding(mut self, padding: u16) -> Self {
         self.padding = padding;
         self
     }
 
+    /// Sets the [`Background`] of the [`Button`].
+    ///
+    /// [`Button`]: struct.Button.html
+    /// [`Background`]: ../../struct.Background.html
     pub fn background(mut self, background: Background) -> Self {
         self.background = Some(background);
         self
     }
 
+    /// Sets the border radius of the [`Button`].
+    ///
+    /// [`Button`]: struct.Button.html
     pub fn border_radius(mut self, border_radius: u16) -> Self {
         self.border_radius = border_radius;
         self
@@ -103,6 +98,9 @@ impl<'a, Message, Element> Button<'a, Message, Element> {
 /// [`Button`]: struct.Button.html
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub struct State {
+    /// Whether the [`Button`] is currently being pressed.
+    ///
+    /// [`Button`]: struct.Button.html
     pub is_pressed: bool,
 }
 
@@ -113,12 +111,4 @@ impl State {
     pub fn new() -> State {
         State::default()
     }
-
-    /// Returns whether the associated [`Button`] is currently being pressed or
-    /// not.
-    ///
-    /// [`Button`]: struct.Button.html
-    pub fn is_pressed(&self) -> bool {
-        self.is_pressed
-    }
 }
diff --git a/core/src/widget/column.rs b/core/src/widget/column.rs
index 4a97ad98..34dbecf7 100644
--- a/core/src/widget/column.rs
+++ b/core/src/widget/column.rs
@@ -7,6 +7,7 @@ use std::u32;
 /// A [`Column`] will try to fill the horizontal space of its container.
 ///
 /// [`Column`]: struct.Column.html
+#[allow(missing_docs)]
 pub struct Column<Element> {
     pub spacing: u16,
     pub padding: u16,
diff --git a/core/src/widget/container.rs b/core/src/widget/container.rs
index 9bc92fe0..3fe340d1 100644
--- a/core/src/widget/container.rs
+++ b/core/src/widget/container.rs
@@ -2,7 +2,11 @@ use crate::{Align, Length};
 
 use std::u32;
 
+/// An element decorating some content.
+///
+/// It is normally used for alignment purposes.
 #[derive(Debug)]
+#[allow(missing_docs)]
 pub struct Container<Element> {
     pub width: Length,
     pub height: Length,
diff --git a/core/src/widget/row.rs b/core/src/widget/row.rs
index 3d882b47..d2b23bdb 100644
--- a/core/src/widget/row.rs
+++ b/core/src/widget/row.rs
@@ -7,6 +7,7 @@ use std::u32;
 /// A [`Row`] will try to fill the horizontal space of its container.
 ///
 /// [`Row`]: struct.Row.html
+#[allow(missing_docs)]
 pub struct Row<Element> {
     pub spacing: u16,
     pub padding: u16,
diff --git a/core/src/widget/scrollable.rs b/core/src/widget/scrollable.rs
index 7f2f0e99..da03cd93 100644
--- a/core/src/widget/scrollable.rs
+++ b/core/src/widget/scrollable.rs
@@ -1,7 +1,11 @@
+//! Navigate an endless amount of content with a scrollbar.
 use crate::{Align, Column, Length, Point, Rectangle};
 
 use std::u32;
 
+/// A widget that can vertically display an infinite amount of content with a
+/// scrollbar.
+#[allow(missing_docs)]
 #[derive(Debug)]
 pub struct Scrollable<'a, Element> {
     pub state: &'a mut State,
@@ -11,6 +15,10 @@ pub struct Scrollable<'a, Element> {
 }
 
 impl<'a, Element> Scrollable<'a, Element> {
+    /// Creates a new [`Scrollable`] with the given [`State`].
+    ///
+    /// [`Scrollable`]: struct.Scrollable.html
+    /// [`State`]: struct.State.html
     pub fn new(state: &'a mut State) -> Self {
         Scrollable {
             state,
@@ -90,17 +98,30 @@ impl<'a, Element> Scrollable<'a, Element> {
     }
 }
 
+/// The local state of a [`Scrollable`].
+///
+/// [`Scrollable`]: struct.Scrollable.html
 #[derive(Debug, Clone, Copy, Default)]
 pub struct State {
+    /// The position where the scrollbar was grabbed at, if it's currently
+    /// grabbed.
     pub scrollbar_grabbed_at: Option<Point>,
     offset: u32,
 }
 
 impl State {
+    /// Creates a new [`State`] with the scrollbar located at the top.
+    ///
+    /// [`State`]: struct.State.html
     pub fn new() -> Self {
         State::default()
     }
 
+    /// Apply a scrolling offset to the current [`State`], given the bounds of
+    /// the [`Scrollable`] and its contents.
+    ///
+    /// [`Scrollable`]: struct.Scrollable.html
+    /// [`State`]: struct.State.html
     pub fn scroll(
         &mut self,
         delta_y: f32,
@@ -117,6 +138,14 @@ impl State {
             as u32;
     }
 
+    /// Moves the scroll position to a relative amount, given the bounds of
+    /// the [`Scrollable`] and its contents.
+    ///
+    /// `0` represents scrollbar at the top, while `1` represents scrollbar at
+    /// the bottom.
+    ///
+    /// [`Scrollable`]: struct.Scrollable.html
+    /// [`State`]: struct.State.html
     pub fn scroll_to(
         &mut self,
         percentage: f32,
@@ -127,6 +156,11 @@ impl State {
             .max(0.0) as u32;
     }
 
+    /// Returns the current scrolling offset of the [`State`], given the bounds
+    /// of the [`Scrollable`] and its contents.
+    ///
+    /// [`Scrollable`]: struct.Scrollable.html
+    /// [`State`]: struct.State.html
     pub fn offset(&self, bounds: Rectangle, content_bounds: Rectangle) -> u32 {
         let hidden_content =
             (content_bounds.height - bounds.height).max(0.0).round() as u32;
@@ -134,6 +168,7 @@ impl State {
         self.offset.min(hidden_content)
     }
 
+    /// Returns whether the scrollbar is currently grabbed or not.
     pub fn is_scrollbar_grabbed(&self) -> bool {
         self.scrollbar_grabbed_at.is_some()
     }
diff --git a/core/src/widget/slider.rs b/core/src/widget/slider.rs
index b65e3991..d6fe8ade 100644
--- a/core/src/widget/slider.rs
+++ b/core/src/widget/slider.rs
@@ -31,19 +31,12 @@ use std::rc::Rc;
 /// ```
 ///
 /// ![Slider drawn by Coffee's renderer](https://github.com/hecrj/coffee/blob/bda9818f823dfcb8a7ad0ff4940b4d4b387b5208/images/ui/slider.png?raw=true)
+#[allow(missing_docs)]
 pub struct Slider<'a, Message> {
-    /// The state of the slider
     pub state: &'a mut State,
-
-    /// The range of the slider
     pub range: RangeInclusive<f32>,
-
-    /// The current value of the slider
     pub value: f32,
-
-    /// The function to produce messages on change
     pub on_change: Rc<Box<dyn Fn(f32) -> Message>>,
-
     pub width: Length,
 }
 
@@ -53,6 +46,7 @@ impl<'a, Message> std::fmt::Debug for Slider<'a, Message> {
             .field("state", &self.state)
             .field("range", &self.range)
             .field("value", &self.value)
+            .field("width", &self.width)
             .finish()
     }
 }
@@ -102,6 +96,9 @@ impl<'a, Message> Slider<'a, Message> {
 /// [`Slider`]: struct.Slider.html
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub struct State {
+    /// Whether the [`Slider`] is currently being dragged or not.
+    ///
+    /// [`Slider`]: struct.Slider.html
     pub is_dragging: bool,
 }
 
diff --git a/core/src/widget/text.rs b/core/src/widget/text.rs
index 0996e7ff..1746160e 100644
--- a/core/src/widget/text.rs
+++ b/core/src/widget/text.rs
@@ -12,6 +12,7 @@ use crate::{Color, Font, Length};
 ///     .size(40);
 /// ```
 #[derive(Debug, Clone)]
+#[allow(missing_docs)]
 pub struct Text {
     pub content: String,
     pub size: Option<u16>,
@@ -48,14 +49,19 @@ impl Text {
         self
     }
 
-    /// Sets the `Color` of the [`Text`].
+    /// Sets the [`Color`] of the [`Text`].
     ///
     /// [`Text`]: struct.Text.html
+    /// [`Color`]: ../../struct.Color.html
     pub fn color<C: Into<Color>>(mut self, color: C) -> Self {
         self.color = Some(color.into());
         self
     }
 
+    /// Sets the [`Font`] of the [`Text`].
+    ///
+    /// [`Text`]: struct.Text.html
+    /// [`Font`]: ../../struct.Font.html
     pub fn font(mut self, font: Font) -> Self {
         self.font = font;
         self
diff --git a/core/src/widget/text_input.rs b/core/src/widget/text_input.rs
index 16c67954..df933380 100644
--- a/core/src/widget/text_input.rs
+++ b/core/src/widget/text_input.rs
@@ -1,5 +1,13 @@
+//! Display fields that can be filled with text.
+//!
+//! A [`TextInput`] has some local [`State`].
+//!
+//! [`TextInput`]: struct.TextInput.html
+//! [`State`]: struct.State.html
 use crate::Length;
 
+/// A widget that can be filled with text by using a keyboard.
+#[allow(missing_docs)]
 pub struct TextInput<'a, Message> {
     pub state: &'a mut State,
     pub placeholder: String,
@@ -13,6 +21,9 @@ pub struct TextInput<'a, Message> {
 }
 
 impl<'a, Message> TextInput<'a, Message> {
+    /// Creates a new [`TextInput`].
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub fn new<F>(
         state: &'a mut State,
         placeholder: &str,
@@ -59,11 +70,18 @@ impl<'a, Message> TextInput<'a, Message> {
         self
     }
 
+    /// Sets the text size of the [`TextInput`].
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub fn size(mut self, size: u16) -> Self {
         self.size = Some(size);
         self
     }
 
+    /// Sets the message that should be produced when the [`TextInput`] is
+    /// focused and the enter key is pressed.
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub fn on_submit(mut self, message: Message) -> Self {
         self.on_submit = Some(message);
         self
@@ -80,17 +98,29 @@ where
     }
 }
 
+/// The state of a [`TextInput`].
+///
+/// [`TextInput`]: struct.TextInput.html
 #[derive(Debug, Default, Clone)]
 pub struct State {
+    /// Whether the [`TextInput`] is focused or not.
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub is_focused: bool,
     cursor_position: usize,
 }
 
 impl State {
+    /// Creates a new [`State`], representing an unfocused [`TextInput`].
+    ///
+    /// [`State`]: struct.State.html
     pub fn new() -> Self {
         Self::default()
     }
 
+    /// Creates a new [`State`], representing a focused [`TextInput`].
+    ///
+    /// [`State`]: struct.State.html
     pub fn focused() -> Self {
         use std::usize;
 
@@ -100,6 +130,9 @@ impl State {
         }
     }
 
+    /// Moves the cursor of a [`TextInput`] to the right.
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub fn move_cursor_right(&mut self, value: &Value) {
         let current = self.cursor_position(value);
 
@@ -108,6 +141,9 @@ impl State {
         }
     }
 
+    /// Moves the cursor of a [`TextInput`] to the left.
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub fn move_cursor_left(&mut self, value: &Value) {
         let current = self.cursor_position(value);
 
@@ -116,41 +152,69 @@ impl State {
         }
     }
 
+    /// Moves the cursor of a [`TextInput`] to the end.
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub fn move_cursor_to_end(&mut self, value: &Value) {
         self.cursor_position = value.len();
     }
 
+    /// Returns the cursor position of a [`TextInput`].
+    ///
+    /// [`TextInput`]: struct.TextInput.html
     pub fn cursor_position(&self, value: &Value) -> usize {
         self.cursor_position.min(value.len())
     }
 }
 
+/// The value of a [`TextInput`].
+///
+/// [`TextInput`]: struct.TextInput.html
 // TODO: Use `unicode-segmentation`
+#[derive(Debug)]
 pub struct Value(Vec<char>);
 
 impl Value {
+    /// Creates a new [`Value`] from a string slice.
+    ///
+    /// [`Value`]: struct.Value.html
     pub fn new(string: &str) -> Self {
         Self(string.chars().collect())
     }
 
+    /// Returns the total amount of `char` in the [`Value`].
+    ///
+    /// [`Value`]: struct.Value.html
     pub fn len(&self) -> usize {
         self.0.len()
     }
 
+    /// Returns a new [`Value`] containing the `char` until the given `index`.
+    ///
+    /// [`Value`]: struct.Value.html
     pub fn until(&self, index: usize) -> Self {
         Self(self.0[..index.min(self.len())].to_vec())
     }
 
+    /// Converts the [`Value`] into a `String`.
+    ///
+    /// [`Value`]: struct.Value.html
     pub fn to_string(&self) -> String {
         use std::iter::FromIterator;
         String::from_iter(self.0.iter())
     }
 
+    /// Inserts a new `char` at the given `index`.
+    ///
+    /// [`Value`]: struct.Value.html
     pub fn insert(&mut self, index: usize, c: char) {
         self.0.insert(index, c);
     }
 
+    /// Removes the `char` at the given `index`.
+    ///
+    /// [`Value`]: struct.Value.html
     pub fn remove(&mut self, index: usize) {
-        self.0.remove(index);
+        let _ = self.0.remove(index);
     }
 }
diff --git a/rustfmt.toml b/rustfmt.toml
index d979d317..7678b63c 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -1 +1,2 @@
 max_width=80
+wrap_comments=true