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refactor(engine): extract the splittable-leaf placement into its own compiler #360

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Merged
DemchaAV merged 1 commit into from
Jul 11, 2026
+311 −166
Merged

refactor(engine): extract the splittable-leaf placement into its own compiler #360

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167 changes: 1 addition & 166 deletions src/main/java/com/demcha/compose/document/layout/LayoutCompiler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -170,7 +170,7 @@ private void compileNode(PreparedNode<DocumentNode> prepared,
}

if (definition.paginationPolicy(node) == PaginationPolicy.SPLITTABLE) {
compileSplittableLeaf(prepared, definition, path, semanticName, parentPath, childIndex, depth, regionX,
SplittableLeafCompiler.compile(prepared, definition, path, semanticName, parentPath, childIndex, depth, regionX,
availableWidth, state, prepareContext, fragmentContext, nodes, fragments);
return;
}
Expand Down Expand Up @@ -859,171 +859,6 @@ private void placeStackLayer(DocumentNode child,
layerCtx);
}

private void compileSplittableLeaf(PreparedNode<DocumentNode> prepared,
NodeDefinition<DocumentNode> definition,
String path,
String semanticName,
String parentPath,
int childIndex,
int depth,
double regionX,
double availableWidth,
CompilerState state,
PrepareContext prepareContext,
FragmentContext fragmentContext,
List<PlacedNode> nodes,
List<PlacedFragment> fragments) {
Margin originalMargin = toMargin(prepared.node().margin());
Padding originalPadding = toPadding(prepared.node().padding());

PreparedNode<DocumentNode> current = prepared;
double firstPlacementX = Double.NaN;
double firstPlacementY = Double.NaN;
int startPage = -1;
int endPage = -1;

while (current != null) {
DocumentNode currentNode = current.node();
Margin currentMargin = toMargin(currentNode.margin());
Padding currentPadding = toPadding(currentNode.padding());
MeasureResult pieceMeasure = current.measureResult();
double pieceOuterHeight = pieceMeasure.height() + currentMargin.vertical();
double fullPageOuterHeight = state.activeInnerHeight();

if (pieceOuterHeight <= state.remainingHeight() + EPS) {
state.touchPage();
if (startPage < 0) {
startPage = state.pageIndex;
}
double placementX = regionX + currentMargin.left();
double placementY = state.pageTop() - state.usedHeight - currentMargin.top() - pieceMeasure.height();
FragmentPlacement placement = new FragmentPlacement(
path,
parentPath,
childIndex,
depth,
state.pageIndex,
placementX,
placementY,
pieceMeasure.width(),
pieceMeasure.height(),
startPage,
state.pageIndex,
currentMargin,
currentPadding);
addPlacedFragments(definition.emitFragments(current, fragmentContext, placement), placement, fragments);

if (Double.isNaN(firstPlacementX)) {
firstPlacementX = placementX;
firstPlacementY = placementY;
}
endPage = state.pageIndex;
state.usedHeight += pieceOuterHeight;
current = null;
continue;
}

double remainingBoxHeight = Math.max(0.0, state.remainingHeight() - currentMargin.vertical());
if (remainingBoxHeight <= EPS && state.usedHeight > EPS) {
state.newPage();
continue;
}

SplitRequest splitRequest = new SplitRequest(
new BoxConstraints(availableWidth, remainingBoxHeight),
remainingBoxHeight,
Math.max(0.0, fullPageOuterHeight - currentMargin.vertical()),
prepareContext);
PreparedSplitResult<DocumentNode> splitResult = definition.split(current, splitRequest);
PreparedNode<DocumentNode> head = splitResult.head();
PreparedNode<DocumentNode> tail = splitResult.tail();

if (head == null) {
if (state.usedHeight > EPS) {
state.newPage();
continue;
}
throw AtomicNodeTooLargeException.forNode(path, pieceOuterHeight, fullPageOuterHeight);
}
if (tail != null && tail.equals(current)) {
throw new IllegalStateException("Split did not make progress for node '" + path
+ "'. The node's NodeDefinition.split() returned the original input as the tail — "
+ "check the definition for an infinite split loop and ensure each split advances.");
}

DocumentNode headNode = head.node();
Margin headMargin = toMargin(headNode.margin());
Padding headPadding = toPadding(headNode.padding());
MeasureResult headMeasure = head.measureResult();
double headOuterHeight = headMeasure.height() + headMargin.vertical();

if (headOuterHeight > state.remainingHeight() + EPS) {
if (state.usedHeight > EPS) {
state.newPage();
continue;
}
throw AtomicNodeTooLargeException.forNode(path, headOuterHeight, fullPageOuterHeight);
}

state.touchPage();
if (startPage < 0) {
startPage = state.pageIndex;
}

double placementX = regionX + headMargin.left();
double placementY = state.pageTop() - state.usedHeight - headMargin.top() - headMeasure.height();
FragmentPlacement placement = new FragmentPlacement(
path,
parentPath,
childIndex,
depth,
state.pageIndex,
placementX,
placementY,
headMeasure.width(),
headMeasure.height(),
startPage,
state.pageIndex,
headMargin,
headPadding);
addPlacedFragments(definition.emitFragments(head, fragmentContext, placement), placement, fragments);

if (Double.isNaN(firstPlacementX)) {
firstPlacementX = placementX;
firstPlacementY = placementY;
}
endPage = state.pageIndex;
state.usedHeight += headOuterHeight;

current = tail;
if (current != null) {
state.newPage();
}
}

MeasureResult originalMeasure = prepared.measureResult();
nodes.add(new PlacedNode(
path,
semanticName,
prepared.node().nodeKind(),
parentPath,
childIndex,
depth,
depth,
firstPlacementX,
firstPlacementY,
firstPlacementX,
firstPlacementY,
originalMeasure.width(),
originalMeasure.height(),
startPage,
endPage,
originalMeasure.width(),
originalMeasure.height(),
originalMargin,
originalPadding));
}

/**
* Compiles a composite or leaf node inside a fixed slot.
*
Expand Down
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