Add more methods to `direction` (#5893)

1 files changed, 52 insertions, 0 deletions

diff --git a/crates/typst-library/src/layout/dir.rs b/crates/typst-library/src/layout/dir.rs
index 9a2e7710..699c8c48 100644
--- a/crates/typst-library/src/layout/dir.rs
+++ b/crates/typst-library/src/layout/dir.rs
@@ -50,6 +50,42 @@ impl Dir {
     pub const TTB: Self = Self::TTB;
     pub const BTT: Self = Self::BTT;
 
+    /// Returns a direction from a starting point.
+    ///
+    /// ```example
+    /// direction.from(left) \
+    /// direction.from(right) \
+    /// direction.from(top) \
+    /// direction.from(bottom)
+    /// ```
+    #[func]
+    pub const fn from(side: Side) -> Dir {
+        match side {
+            Side::Left => Self::LTR,
+            Side::Right => Self::RTL,
+            Side::Top => Self::TTB,
+            Side::Bottom => Self::BTT,
+        }
+    }
+
+    /// Returns a direction from an end point.
+    ///
+    /// ```example
+    /// direction.to(left) \
+    /// direction.to(right) \
+    /// direction.to(top) \
+    /// direction.to(bottom)
+    /// ```
+    #[func]
+    pub const fn to(side: Side) -> Dir {
+        match side {
+            Side::Right => Self::LTR,
+            Side::Left => Self::RTL,
+            Side::Bottom => Self::TTB,
+            Side::Top => Self::BTT,
+        }
+    }
+
     /// The axis this direction belongs to, either `{"horizontal"}` or
     /// `{"vertical"}`.
     ///
@@ -65,6 +101,22 @@ impl Dir {
         }
     }
 
+    /// The corresponding sign, for use in calculations.
+    ///
+    /// ```example
+    /// #ltr.sign() \
+    /// #rtl.sign() \
+    /// #ttb.sign() \
+    /// #btt.sign()
+    /// ```
+    #[func]
+    pub const fn sign(self) -> i64 {
+        match self {
+            Self::LTR | Self::TTB => 1,
+            Self::RTL | Self::BTT => -1,
+        }
+    }
+
     /// The start point of this direction, as an alignment.
     ///
     /// ```example