Improve `Padding` ergonomics

We expose free functions for creating a `Padding`
and methods with the same name to modify its fields.

5 files changed, 70 insertions, 47 deletions

diff --git a/core/src/lib.rs b/core/src/lib.rs
index 32156441..40a288e5 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -20,6 +20,7 @@ pub mod keyboard;
 pub mod layout;
 pub mod mouse;
 pub mod overlay;
+pub mod padding;
 pub mod renderer;
 pub mod svg;
 pub mod text;
@@ -35,7 +36,6 @@ mod color;
 mod content_fit;
 mod element;
 mod length;
-mod padding;
 mod pixels;
 mod point;
 mod rectangle;
diff --git a/core/src/padding.rs b/core/src/padding.rs
index b8c941d8..a0915fbc 100644
--- a/core/src/padding.rs
+++ b/core/src/padding.rs
@@ -1,3 +1,4 @@
+//! Space stuff around the perimeter.
 use crate::{Pixels, Size};
 
 /// An amount of space to pad for each side of a box
@@ -9,7 +10,6 @@ use crate::{Pixels, Size};
 /// #
 /// let padding = Padding::from(20);              // 20px on all sides
 /// let padding = Padding::from([10, 20]);        // top/bottom, left/right
-/// let padding = Padding::from([5, 10, 15, 20]); // top, right, bottom, left
 /// ```
 ///
 /// Normally, the `padding` method of a widget will ask for an `Into<Padding>`,
@@ -31,7 +31,6 @@ use crate::{Pixels, Size};
 ///
 /// let widget = Widget::new().padding(20);              // 20px on all sides
 /// let widget = Widget::new().padding([10, 20]);        // top/bottom, left/right
-/// let widget = Widget::new().padding([5, 10, 15, 20]); // top, right, bottom, left
 /// ```
 #[derive(Debug, Copy, Clone)]
 pub struct Padding {
@@ -45,6 +44,43 @@ pub struct Padding {
     pub left: f32,
 }
 
+/// Create a [`Padding`] that is equal on all sides.
+pub fn all(padding: impl Into<Pixels>) -> Padding {
+    Padding::new(padding.into().0)
+}
+
+/// Create some top [`Padding`].
+pub fn top(padding: impl Into<Pixels>) -> Padding {
+    Padding {
+        top: padding.into().0,
+        ..Padding::ZERO
+    }
+}
+
+/// Create some bottom [`Padding`].
+pub fn bottom(padding: impl Into<Pixels>) -> Padding {
+    Padding {
+        bottom: padding.into().0,
+        ..Padding::ZERO
+    }
+}
+
+/// Create some left [`Padding`].
+pub fn left(padding: impl Into<Pixels>) -> Padding {
+    Padding {
+        left: padding.into().0,
+        ..Padding::ZERO
+    }
+}
+
+/// Create some right [`Padding`].
+pub fn right(padding: impl Into<Pixels>) -> Padding {
+    Padding {
+        right: padding.into().0,
+        ..Padding::ZERO
+    }
+}
+
 impl Padding {
     /// Padding of zero
     pub const ZERO: Padding = Padding {
@@ -64,35 +100,43 @@ impl Padding {
         }
     }
 
-    /// Create some top [`Padding`].
-    pub fn top(padding: impl Into<Pixels>) -> Self {
+    /// Sets the [`top`] of the [`Padding`].
+    ///
+    /// [`top`]: Self::top
+    pub fn top(self, top: impl Into<Pixels>) -> Self {
         Self {
-            top: padding.into().0,
-            ..Self::ZERO
+            top: top.into().0,
+            ..self
         }
     }
 
-    /// Create some right [`Padding`].
-    pub fn right(padding: impl Into<Pixels>) -> Self {
+    /// Sets the [`bottom`] of the [`Padding`].
+    ///
+    /// [`bottom`]: Self::bottom
+    pub fn bottom(self, bottom: impl Into<Pixels>) -> Self {
         Self {
-            right: padding.into().0,
-            ..Self::ZERO
+            bottom: bottom.into().0,
+            ..self
         }
     }
 
-    /// Create some bottom [`Padding`].
-    pub fn bottom(padding: impl Into<Pixels>) -> Self {
+    /// Sets the [`left`] of the [`Padding`].
+    ///
+    /// [`left`]: Self::left
+    pub fn left(self, left: impl Into<Pixels>) -> Self {
         Self {
-            bottom: padding.into().0,
-            ..Self::ZERO
+            left: left.into().0,
+            ..self
         }
     }
 
-    /// Create some left [`Padding`].
-    pub fn left(padding: impl Into<Pixels>) -> Self {
+    /// Sets the [`right`] of the [`Padding`].
+    ///
+    /// [`right`]: Self::right
+    pub fn right(self, right: impl Into<Pixels>) -> Self {
         Self {
-            left: padding.into().0,
-            ..Self::ZERO
+            right: right.into().0,
+            ..self
         }
     }
 
@@ -143,17 +187,6 @@ impl From<[u16; 2]> for Padding {
     }
 }
 
-impl From<[u16; 4]> for Padding {
-    fn from(p: [u16; 4]) -> Self {
-        Padding {
-            top: f32::from(p[0]),
-            right: f32::from(p[1]),
-            bottom: f32::from(p[2]),
-            left: f32::from(p[3]),
-        }
-    }
-}
-
 impl From<f32> for Padding {
     fn from(p: f32) -> Self {
         Padding {
@@ -176,17 +209,6 @@ impl From<[f32; 2]> for Padding {
     }
 }
 
-impl From<[f32; 4]> for Padding {
-    fn from(p: [f32; 4]) -> Self {
-        Padding {
-            top: p[0],
-            right: p[1],
-            bottom: p[2],
-            left: p[3],
-        }
-    }
-}
-
 impl From<Padding> for Size {
     fn from(padding: Padding) -> Self {
         Self::new(padding.horizontal(), padding.vertical())
diff --git a/examples/screenshot/src/main.rs b/examples/screenshot/src/main.rs
index 7fc87446..2d980dd9 100644
--- a/examples/screenshot/src/main.rs
+++ b/examples/screenshot/src/main.rs
@@ -170,7 +170,7 @@ impl Example {
             column![
                 column![
                     button(centered_text("Screenshot!"))
-                        .padding([10, 20, 10, 20])
+                        .padding([10, 20])
                         .width(Fill)
                         .on_press(Message::Screenshot),
                     if !self.png_saving {
@@ -182,7 +182,7 @@ impl Example {
                             .style(button::secondary)
                     }
                     .style(button::secondary)
-                    .padding([10, 20, 10, 20])
+                    .padding([10, 20])
                     .width(Fill)
                 ]
                 .spacing(10),
@@ -191,7 +191,7 @@ impl Example {
                     button(centered_text("Crop"))
                         .on_press(Message::Crop)
                         .style(button::danger)
-                        .padding([10, 20, 10, 20])
+                        .padding([10, 20])
                         .width(Fill),
                 ]
                 .spacing(10)
diff --git a/examples/scrollable/src/main.rs b/examples/scrollable/src/main.rs
index a1c23976..de4f2f9a 100644
--- a/examples/scrollable/src/main.rs
+++ b/examples/scrollable/src/main.rs
@@ -213,7 +213,7 @@ impl ScrollableDemo {
                         scroll_to_beginning_button(),
                     ]
                     .align_x(Center)
-                    .padding([40, 0, 40, 0])
+                    .padding([40, 0])
                     .spacing(40),
                 )
                 .direction(scrollable::Direction::Vertical(
@@ -239,7 +239,7 @@ impl ScrollableDemo {
                     ]
                     .height(450)
                     .align_y(Center)
-                    .padding([0, 40, 0, 40])
+                    .padding([0, 40])
                     .spacing(40),
                 )
                 .direction(scrollable::Direction::Horizontal(
@@ -281,7 +281,7 @@ impl ScrollableDemo {
                         scroll_to_beginning_button(),
                     ]
                     .align_y(Center)
-                    .padding([0, 40, 0, 40])
+                    .padding([0, 40])
                     .spacing(40),
                 )
                 .direction({
diff --git a/src/lib.rs b/src/lib.rs
index 8c6aeea3..7ced9a57 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -196,6 +196,7 @@ pub use crate::core::alignment;
 pub use crate::core::border;
 pub use crate::core::color;
 pub use crate::core::gradient;
+pub use crate::core::padding;
 pub use crate::core::theme;
 pub use crate::core::{
     Alignment, Background, Border, Color, ContentFit, Degrees, Gradient,