Layout improvements

2 files changed, 28 insertions, 14 deletions

diff --git a/src/layout/constraints.rs b/src/layout/constraints.rs
index 36cfa582..b72254d7 100644
--- a/src/layout/constraints.rs
+++ b/src/layout/constraints.rs
@@ -1,5 +1,6 @@
 use std::rc::Rc;
 
+use super::Regions;
 use crate::frame::Frame;
 use crate::geom::{Length, Linear, Size, Spec};
 
@@ -59,6 +60,17 @@ impl Constraints {
         }
     }
 
+    /// Create tight constraints for a region.
+    pub fn tight(regions: &Regions) -> Self {
+        Self {
+            min: Spec::default(),
+            max: Spec::default(),
+            exact: regions.current.to_spec().map(Some),
+            base: regions.base.to_spec().map(Some),
+            expand: regions.expand,
+        }
+    }
+
     /// Check whether the constraints are fullfilled in a region with the given
     /// properties.
     pub fn check(&self, current: Size, base: Size, expand: Spec<bool>) -> bool {
diff --git a/src/layout/regions.rs b/src/layout/regions.rs
index 39297914..0ef92543 100644
--- a/src/layout/regions.rs
+++ b/src/layout/regions.rs
@@ -1,4 +1,4 @@
-use crate::geom::{Size, Spec};
+use crate::geom::{Length, Size, Spec};
 
 /// A sequence of regions to layout into.
 #[derive(Debug, Clone)]
@@ -13,9 +13,6 @@ pub struct Regions {
     pub last: Option<Size>,
     /// Whether nodes should expand to fill the regions instead of shrinking to
     /// fit the content.
-    ///
-    /// This property is only handled by nodes that have the ability to control
-    /// their own size.
     pub expand: Spec<bool>,
 }
 
@@ -52,13 +49,26 @@ impl Regions {
         regions
     }
 
-    /// Whether `current` is a fully sized (untouched) copy of the last region.
+    /// Whether the current region is full and a region break is called for.
+    pub fn is_full(&self) -> bool {
+        Length::zero().fits(self.current.h) && !self.in_last()
+    }
+
+    /// Whether `current` is the last usable region.
     ///
     /// If this is true, calling `next()` will have no effect.
-    pub fn in_full_last(&self) -> bool {
+    pub fn in_last(&self) -> bool {
         self.backlog.len() == 0 && self.last.map_or(true, |size| self.current == size)
     }
 
+    /// Advance to the next region if there is any.
+    pub fn next(&mut self) {
+        if let Some(size) = self.backlog.next().or(self.last) {
+            self.current = size;
+            self.base = size;
+        }
+    }
+
     /// An iterator that returns pairs of `(current, base)` that are equivalent
     /// to what would be produced by calling [`next()`](Self::next) repeatedly
     /// until all regions are exhausted.
@@ -69,14 +79,6 @@ impl Regions {
         first.chain(backlog.chain(last).map(|&s| (s, s)))
     }
 
-    /// Advance to the next region if there is any.
-    pub fn next(&mut self) {
-        if let Some(size) = self.backlog.next().or(self.last) {
-            self.current = size;
-            self.base = size;
-        }
-    }
-
     /// Mutate all contained sizes in place.
     pub fn mutate<F>(&mut self, mut f: F)
     where