Add centering of layouts.

src/layout/mod.rs

@@ -325,7 +325,9 @@ impl Layout<'_> {
 
         assert!(Self::place_block(problem, &mut blocks, rng));
 
-        Layout { problem, blocks }
+        let mut l = Layout { problem, blocks };
+        l.center();
+        l
     }
 
     fn place_block<R: Rng + ?Sized>(
@@ -381,6 +383,28 @@ impl Layout<'_> {
         false
     }
 
+    pub fn get_aabb(&self) -> AABB {
+        self.blocks
+            .iter()
+            .map(|b| b.get_aabb())
+            .reduce(AABB::combine)
+            .expect("At least one block is required.")
+    }
+
+    pub fn center(&mut self) {
+        let aabb = self.get_aabb();
+
+        let rest = self.problem.size - aabb.size();
+
+        let new_min = Position::new(rest.x / 2, rest.y / 2);
+
+        let t = Transformation::new(Direction::Up, new_min - aabb.min());
+
+        for b in &mut self.blocks {
+            *b = b.transform(t);
+        }
+    }
+
     /// Mutate existing layout, creating a valid layout
     pub fn mutate<R: Rng + ?Sized>(&self, rng: &mut R) -> Self {
         let mut s = self.clone();
@@ -395,11 +419,12 @@ impl Layout<'_> {
         loop {
             let p = r.choose_weighted(rng, |i| i.1).unwrap();
 
-            if p.0(&mut s, rng) && rng.gen_bool(0.05) {
+            if p.0(&mut s, rng) && rng.gen_bool(0.2) {
                 break;
             }
         }
 
+        s.center();
         s
     }