dev: Minor fixes to `CircuitLayout`

- Default view height is now the circuit size.
- Cells are now always shaded on top of any drawn regions.

src/dev/graph/layout.rs

@@ -123,7 +123,7 @@ impl CircuitLayout {
         };
 
         let view_width = self.view_width.unwrap_or(0..total_columns);
-        let view_height = self.view_height.unwrap_or(0..layout.total_rows);
+        let view_height = self.view_height.unwrap_or(0..n);
         let view_bottom = view_height.end;
 
         // Prepare the grid layout. We render a red background for advice columns, white for
@@ -207,10 +207,10 @@ impl CircuitLayout {
 
         // Render the regions!
         let mut labels = if self.hide_labels { None } else { Some(vec![]) };
-        for region in layout.regions {
+        for region in &layout.regions {
             if let Some(offset) = region.offset {
                 // Sort the region's columns according to the defined ordering.
-                let mut columns: Vec<_> = region.columns.into_iter().collect();
+                let mut columns: Vec<_> = region.columns.iter().cloned().collect();
                 columns.sort_unstable_by_key(|a| column_index(&cs, *a));
 
                 // Render contiguous parts of the same region as a single box.
@@ -237,13 +237,15 @@ impl CircuitLayout {
                         labels.push((region.name.clone(), (start, offset)));
                     }
                 }
+            }
+        }
 
         // Darken the cells of the region that have been assigned to.
+        for region in layout.regions {
             for (column, row) in region.cells {
                 draw_cell(&root, column_index(&cs, column), row)?;
             }
         }
-        }
 
         // Darken any loose cells that have been assigned to.
         for (column, row) in layout.loose_cells {