Add rect-layout leaves-to-start setting

1 files changed, 28 insertions, 1 deletions

diff --git a/src/lib.ts b/src/lib.ts
index e83429d..0a23686 100644
--- a/src/lib.ts
+++ b/src/lib.ts
@@ -143,7 +143,8 @@ export type LayoutOptions = {
 	maxTileSz: number;
 	layoutType: 'sqr' | 'rect' | 'sweep'; // The LayoutFn function to use
 	rectMode: 'horz' | 'vert' | 'linear' | 'auto' | 'auto first-row';
-		// Layout in 1 row, 1 column, 1 row or column, or multiple rows (with/without first-row-heuristic)
+		// Rect layout in 1 row, 1 column, 1 row or column, or multiple rows (with/without first-row-heuristic)
+	rectSepLeaves: boolean; // Rect layout moves leaf nodes to start
 	sweepMode: 'left' | 'top' | 'shorter' | 'auto'; // Sweep to left, top, shorter-side, or to minimise empty space
 	sweptNodesPrio: 'linear' | 'sqrt' | 'pow-2/3'; // Specifies allocation of space to swept-vs-remaining nodes
 	sweepingToParent: boolean; // Allow swept nodes to occupy empty space in a parent's swept-leaves area
@@ -341,6 +342,24 @@ let rectLayout: LayoutFn = function (node, pos, dims, showHeader, allowCollapse,
 	if (newDims[0] * newDims[1] <= 0){
 		return false;
 	}
+	// Reorder children if applicable
+	let oldNode: LayoutNode, oldChildIdxs: number[];
+	if (opts.rectSepLeaves){ // Change 'node' to leaves-to-start version, and store old-child-order indices
+		oldNode = node;
+		let leaves: LayoutNode[] = [], nonLeaves: LayoutNode[] = [];
+		let leafIdxs = [] as number[], nonLeafIdxs = [] as number[];
+		node.children.forEach((child, idx) => {
+			if (child.children.length == 0){
+				leaves.push(child);
+				leafIdxs.push(idx);
+			} else {
+				nonLeaves.push(child);
+				nonLeafIdxs.push(idx);
+			}
+		});
+		node = new LayoutNode(node.tolNode, leaves.concat(...nonLeaves));
+		oldChildIdxs = leafIdxs.concat(...nonLeafIdxs);
+	}
 	// Try finding arrangement with low empty space
 	// Done by searching possible rows groupings, allocating within rows using dCounts, and trimming empty space
 	let numChildren = node.children.length;
@@ -519,6 +538,9 @@ let rectLayout: LayoutFn = function (node, pos, dims, showHeader, allowCollapse,
 		}
 	}
 	if (usedTree == null){ // If no found layout
+		if (opts.rectSepLeaves){
+			node = oldNode!;
+		}
 		if (allowCollapse){
 			node.children = [];
 			LayoutNode.updateDCounts(node, 1 - node.dCount);
@@ -527,6 +549,11 @@ let rectLayout: LayoutFn = function (node, pos, dims, showHeader, allowCollapse,
 		return false;
 	}
 	// Create layout
+	if (opts.rectSepLeaves){ // Restore old 'node', and reorder 'usedTree's children to match
+		node = oldNode!;
+		let usedChildren = [...usedTree.children];
+		range(numChildren).forEach(idx => usedTree!.children[oldChildIdxs[idx]] = usedChildren[idx]);
+	}
 	usedTree.copyTreeForRender(node);
 	let usedDims: [number, number] = [dims[0] - usedEmpRight, dims[1] - usedEmpBottom];
 	node.assignLayoutData(pos, usedDims, {showHeader, empSpc: lowestEmpSpc});