Make many functions `const`

The point is to set up repeated components or boilerplate before their
use sites.

The majority of these make sense as `const`. However, some functions
such as those regarding state may not make sense as `const`.

7 files changed, 34 insertions, 31 deletions

diff --git a/native/src/layout/limits.rs b/native/src/layout/limits.rs
index 2705a47d..5f456871 100644
--- a/native/src/layout/limits.rs
+++ b/native/src/layout/limits.rs
@@ -20,7 +20,7 @@ impl Limits {
     ///
     /// [`Limits`]: struct.Limits.html
     /// [`Size`]: ../struct.Size.html
-    pub fn new(min: Size, max: Size) -> Limits {
+    pub const fn new(min: Size, max: Size) -> Limits {
         Limits {
             min,
             max,
@@ -32,7 +32,7 @@ impl Limits {
     ///
     /// [`Limits`]: struct.Limits.html
     /// [`Size`]: ../struct.Size.html
-    pub fn min(&self) -> Size {
+    pub const fn min(&self) -> Size {
         self.min
     }
 
@@ -40,7 +40,7 @@ impl Limits {
     ///
     /// [`Limits`]: struct.Limits.html
     /// [`Size`]: ../struct.Size.html
-    pub fn max(&self) -> Size {
+    pub const fn max(&self) -> Size {
         self.max
     }
 
diff --git a/native/src/layout/node.rs b/native/src/layout/node.rs
index ed1cd3da..3b63914e 100644
--- a/native/src/layout/node.rs
+++ b/native/src/layout/node.rs
@@ -12,7 +12,7 @@ impl Node {
     ///
     /// [`Node`]: struct.Node.html
     /// [`Size`]: ../struct.Size.html
-    pub fn new(size: Size) -> Self {
+    pub const fn new(size: Size) -> Self {
         Self::with_children(size, Vec::new())
     }
 
@@ -20,7 +20,7 @@ impl Node {
     ///
     /// [`Node`]: struct.Node.html
     /// [`Size`]: ../struct.Size.html
-    pub fn with_children(size: Size, children: Vec<Node>) -> Self {
+    pub const fn with_children(size: Size, children: Vec<Node>) -> Self {
         Node {
             bounds: Rectangle {
                 x: 0.0,
@@ -36,14 +36,14 @@ impl Node {
     ///
     /// [`Node`]: struct.Node.html
     /// [`Size`]: ../struct.Size.html
-    pub fn size(&self) -> Size {
+    pub const fn size(&self) -> Size {
         Size::new(self.bounds.width, self.bounds.height)
     }
 
     /// Returns the bounds of the [`Node`].
     ///
     /// [`Node`]: struct.Node.html
-    pub fn bounds(&self) -> Rectangle {
+    pub const fn bounds(&self) -> Rectangle {
         self.bounds
     }
 
diff --git a/native/src/widget/column.rs b/native/src/widget/column.rs
index cdcf25af..104fdb94 100644
--- a/native/src/widget/column.rs
+++ b/native/src/widget/column.rs
@@ -28,7 +28,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Creates an empty [`Column`].
     ///
     /// [`Column`]: struct.Column.html
-    pub fn new() -> Self {
+    pub const fn new() -> Self {
         Column {
             spacing: 0,
             padding: 0,
@@ -46,7 +46,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Custom margins per element do not exist in Iced. You should use this
     /// method instead! While less flexible, it helps you keep spacing between
     /// elements consistent.
-    pub fn spacing(mut self, units: u16) -> Self {
+    pub const fn spacing(mut self, units: u16) -> Self {
         self.spacing = units;
         self
     }
@@ -54,7 +54,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Sets the padding of the [`Column`].
     ///
     /// [`Column`]: struct.Column.html
-    pub fn padding(mut self, units: u16) -> Self {
+    pub const fn padding(mut self, units: u16) -> Self {
         self.padding = units;
         self
     }
@@ -62,7 +62,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Sets the width of the [`Column`].
     ///
     /// [`Column`]: struct.Column.html
-    pub fn width(mut self, width: Length) -> Self {
+    pub const fn width(mut self, width: Length) -> Self {
         self.width = width;
         self
     }
@@ -70,7 +70,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Sets the height of the [`Column`].
     ///
     /// [`Column`]: struct.Column.html
-    pub fn height(mut self, height: Length) -> Self {
+    pub const fn height(mut self, height: Length) -> Self {
         self.height = height;
         self
     }
@@ -78,7 +78,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Sets the maximum width of the [`Column`].
     ///
     /// [`Column`]: struct.Column.html
-    pub fn max_width(mut self, max_width: u32) -> Self {
+    pub const fn max_width(mut self, max_width: u32) -> Self {
         self.max_width = max_width;
         self
     }
@@ -86,7 +86,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Sets the maximum height of the [`Column`] in pixels.
     ///
     /// [`Column`]: struct.Column.html
-    pub fn max_height(mut self, max_height: u32) -> Self {
+    pub const fn max_height(mut self, max_height: u32) -> Self {
         self.max_height = max_height;
         self
     }
@@ -94,7 +94,7 @@ impl<'a, Message, Renderer> Column<'a, Message, Renderer> {
     /// Sets the horizontal alignment of the contents of the [`Column`] .
     ///
     /// [`Column`]: struct.Column.html
-    pub fn align_items(mut self, align: Align) -> Self {
+    pub const fn align_items(mut self, align: Align) -> Self {
         self.align_items = align;
         self
     }
diff --git a/native/src/widget/image.rs b/native/src/widget/image.rs
index 4c588c9d..5cfe074f 100644
--- a/native/src/widget/image.rs
+++ b/native/src/widget/image.rs
@@ -37,7 +37,7 @@ impl Image {
     /// Sets the width of the [`Image`] boundaries.
     ///
     /// [`Image`]: struct.Image.html
-    pub fn width(mut self, width: Length) -> Self {
+    pub const fn width(mut self, width: Length) -> Self {
         self.width = width;
         self
     }
@@ -45,7 +45,7 @@ impl Image {
     /// Sets the height of the [`Image`] boundaries.
     ///
     /// [`Image`]: struct.Image.html
-    pub fn height(mut self, height: Length) -> Self {
+    pub const fn height(mut self, height: Length) -> Self {
         self.height = height;
         self
     }
diff --git a/native/src/widget/row.rs b/native/src/widget/row.rs
index c854aff7..e9b8654c 100644
--- a/native/src/widget/row.rs
+++ b/native/src/widget/row.rs
@@ -28,7 +28,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Creates an empty [`Row`].
     ///
     /// [`Row`]: struct.Row.html
-    pub fn new() -> Self {
+    pub const fn new() -> Self {
         Row {
             spacing: 0,
             padding: 0,
@@ -46,7 +46,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Custom margins per element do not exist in Iced. You should use this
     /// method instead! While less flexible, it helps you keep spacing between
     /// elements consistent.
-    pub fn spacing(mut self, units: u16) -> Self {
+    pub const fn spacing(mut self, units: u16) -> Self {
         self.spacing = units;
         self
     }
@@ -54,7 +54,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Sets the padding of the [`Row`].
     ///
     /// [`Row`]: struct.Row.html
-    pub fn padding(mut self, units: u16) -> Self {
+    pub const fn padding(mut self, units: u16) -> Self {
         self.padding = units;
         self
     }
@@ -62,7 +62,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Sets the width of the [`Row`].
     ///
     /// [`Row`]: struct.Row.html
-    pub fn width(mut self, width: Length) -> Self {
+    pub const fn width(mut self, width: Length) -> Self {
         self.width = width;
         self
     }
@@ -70,7 +70,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Sets the height of the [`Row`].
     ///
     /// [`Row`]: struct.Row.html
-    pub fn height(mut self, height: Length) -> Self {
+    pub const fn height(mut self, height: Length) -> Self {
         self.height = height;
         self
     }
@@ -78,7 +78,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Sets the maximum width of the [`Row`].
     ///
     /// [`Row`]: struct.Row.html
-    pub fn max_width(mut self, max_width: u32) -> Self {
+    pub const fn max_width(mut self, max_width: u32) -> Self {
         self.max_width = max_width;
         self
     }
@@ -86,7 +86,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Sets the maximum height of the [`Row`].
     ///
     /// [`Row`]: struct.Row.html
-    pub fn max_height(mut self, max_height: u32) -> Self {
+    pub const fn max_height(mut self, max_height: u32) -> Self {
         self.max_height = max_height;
         self
     }
@@ -94,7 +94,7 @@ impl<'a, Message, Renderer> Row<'a, Message, Renderer> {
     /// Sets the vertical alignment of the contents of the [`Row`] .
     ///
     /// [`Row`]: struct.Row.html
-    pub fn align_items(mut self, align: Align) -> Self {
+    pub const fn align_items(mut self, align: Align) -> Self {
         self.align_items = align;
         self
     }
diff --git a/native/src/widget/slider.rs b/native/src/widget/slider.rs
index f07ea7cd..a8915da1 100644
--- a/native/src/widget/slider.rs
+++ b/native/src/widget/slider.rs
@@ -95,8 +95,8 @@ impl State {
     /// Creates a new [`State`].
     ///
     /// [`State`]: struct.State.html
-    pub fn new() -> State {
-        State::default()
+    pub const fn new() -> State {
+        State { is_dragging: false }
     }
 }
 
diff --git a/native/src/widget/text_input.rs b/native/src/widget/text_input.rs
index f97ed424..0246f0d5 100644
--- a/native/src/widget/text_input.rs
+++ b/native/src/widget/text_input.rs
@@ -326,14 +326,17 @@ impl State {
     /// Creates a new [`State`], representing an unfocused [`TextInput`].
     ///
     /// [`State`]: struct.State.html
-    pub fn new() -> Self {
-        Self::default()
+    pub const fn new() -> Self {
+        Self {
+            is_focused: false,
+            cursor_position: 0,
+        }
     }
 
     /// Creates a new [`State`], representing a focused [`TextInput`].
     ///
     /// [`State`]: struct.State.html
-    pub fn focused() -> Self {
+    pub const fn focused() -> Self {
         use std::usize;
 
         Self {
@@ -345,7 +348,7 @@ impl State {
     /// Returns whether the [`TextInput`] is currently focused or not.
     ///
     /// [`TextInput`]: struct.TextInput.html
-    pub fn is_focused(&self) -> bool {
+    pub const fn is_focused(&self) -> bool {
         self.is_focused
     }