Add Margin to epaint (#4231)

Moved from `egui`

crates/epaint/src/lib.rs

@@ -27,6 +27,7 @@
 
 mod bezier;
 pub mod image;
+mod margin;
 mod mesh;
 pub mod mutex;
 mod shadow;
@@ -41,9 +42,10 @@ mod texture_handle;
 pub mod textures;
 pub mod util;
 
-pub use {
+pub use self::{
     bezier::{CubicBezierShape, QuadraticBezierShape},
     image::{ColorImage, FontImage, ImageData, ImageDelta},
+    margin::Margin,
     mesh::{Mesh, Mesh16, Vertex},
     shadow::Shadow,
     shape::{

crates/epaint/src/margin.rs

@@ -0,0 +1,211 @@
+use emath::{vec2, Rect, Vec2};
+
+/// A value for all four sides of a rectangle,
+/// often used to express padding or spacing.
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct Margin {
+    pub left: f32,
+    pub right: f32,
+    pub top: f32,
+    pub bottom: f32,
+}
+
+impl Margin {
+    pub const ZERO: Self = Self {
+        left: 0.0,
+        right: 0.0,
+        top: 0.0,
+        bottom: 0.0,
+    };
+
+    #[inline]
+    pub const fn same(margin: f32) -> Self {
+        Self {
+            left: margin,
+            right: margin,
+            top: margin,
+            bottom: margin,
+        }
+    }
+
+    /// Margins with the same size on opposing sides
+    #[inline]
+    pub const fn symmetric(x: f32, y: f32) -> Self {
+        Self {
+            left: x,
+            right: x,
+            top: y,
+            bottom: y,
+        }
+    }
+
+    /// Total margins on both sides
+    #[inline]
+    pub fn sum(&self) -> Vec2 {
+        vec2(self.left + self.right, self.top + self.bottom)
+    }
+
+    #[inline]
+    pub const fn left_top(&self) -> Vec2 {
+        vec2(self.left, self.top)
+    }
+
+    #[inline]
+    pub const fn right_bottom(&self) -> Vec2 {
+        vec2(self.right, self.bottom)
+    }
+
+    #[inline]
+    pub fn is_same(&self) -> bool {
+        self.left == self.right && self.left == self.top && self.left == self.bottom
+    }
+
+    #[inline]
+    pub fn expand_rect(&self, rect: Rect) -> Rect {
+        Rect::from_min_max(rect.min - self.left_top(), rect.max + self.right_bottom())
+    }
+
+    #[inline]
+    pub fn shrink_rect(&self, rect: Rect) -> Rect {
+        Rect::from_min_max(rect.min + self.left_top(), rect.max - self.right_bottom())
+    }
+}
+
+impl From<f32> for Margin {
+    #[inline]
+    fn from(v: f32) -> Self {
+        Self::same(v)
+    }
+}
+
+impl From<Vec2> for Margin {
+    #[inline]
+    fn from(v: Vec2) -> Self {
+        Self::symmetric(v.x, v.y)
+    }
+}
+
+impl std::ops::Add for Margin {
+    type Output = Self;
+
+    #[inline]
+    fn add(self, other: Self) -> Self {
+        Self {
+            left: self.left + other.left,
+            right: self.right + other.right,
+            top: self.top + other.top,
+            bottom: self.bottom + other.bottom,
+        }
+    }
+}
+
+impl std::ops::Add<f32> for Margin {
+    type Output = Self;
+
+    #[inline]
+    fn add(self, v: f32) -> Self {
+        Self {
+            left: self.left + v,
+            right: self.right + v,
+            top: self.top + v,
+            bottom: self.bottom + v,
+        }
+    }
+}
+
+impl std::ops::AddAssign<f32> for Margin {
+    #[inline]
+    fn add_assign(&mut self, v: f32) {
+        self.left += v;
+        self.right += v;
+        self.top += v;
+        self.bottom += v;
+    }
+}
+
+impl std::ops::Div<f32> for Margin {
+    type Output = Self;
+
+    #[inline]
+    fn div(self, v: f32) -> Self {
+        Self {
+            left: self.left / v,
+            right: self.right / v,
+            top: self.top / v,
+            bottom: self.bottom / v,
+        }
+    }
+}
+
+impl std::ops::DivAssign<f32> for Margin {
+    #[inline]
+    fn div_assign(&mut self, v: f32) {
+        self.left /= v;
+        self.right /= v;
+        self.top /= v;
+        self.bottom /= v;
+    }
+}
+
+impl std::ops::Mul<f32> for Margin {
+    type Output = Self;
+
+    #[inline]
+    fn mul(self, v: f32) -> Self {
+        Self {
+            left: self.left * v,
+            right: self.right * v,
+            top: self.top * v,
+            bottom: self.bottom * v,
+        }
+    }
+}
+
+impl std::ops::MulAssign<f32> for Margin {
+    #[inline]
+    fn mul_assign(&mut self, v: f32) {
+        self.left *= v;
+        self.right *= v;
+        self.top *= v;
+        self.bottom *= v;
+    }
+}
+
+impl std::ops::Sub for Margin {
+    type Output = Self;
+
+    #[inline]
+    fn sub(self, other: Self) -> Self {
+        Self {
+            left: self.left - other.left,
+            right: self.right - other.right,
+            top: self.top - other.top,
+            bottom: self.bottom - other.bottom,
+        }
+    }
+}
+
+impl std::ops::Sub<f32> for Margin {
+    type Output = Self;
+
+    #[inline]
+    fn sub(self, v: f32) -> Self {
+        Self {
+            left: self.left - v,
+            right: self.right - v,
+            top: self.top - v,
+            bottom: self.bottom - v,
+        }
+    }
+}
+
+impl std::ops::SubAssign<f32> for Margin {
+    #[inline]
+    fn sub_assign(&mut self, v: f32) {
+        self.left -= v;
+        self.right -= v;
+        self.top -= v;
+        self.bottom -= v;
+    }
+}