Commit both corner-resize dimensions in one host transaction

designer-kit-ui/src/main/java/de/neitzel/fxdesigner/kit/DesignerPane.java

@@ -109,7 +109,8 @@ public final class DesignerPane extends BorderPane implements AutoCloseable {
   private DocumentSnapshot draft;
   private FxmlProjection projection;
   private DesignerWorkflow workflow;
-  private boolean loading, closed, pending, last;
+  private boolean loading, closed, pending, last, canvasCommitQueued;
+  private long canvasGeneration;
   private final java.util.concurrent.atomic.AtomicLong renderSequence =
       new java.util.concurrent.atomic.AtomicLong();
   private AutoCloseable changes;
@@ -205,6 +206,7 @@ public final class DesignerPane extends BorderPane implements AutoCloseable {
         .addListener(
             (o, a, b) -> {
               if (!loading) {
+                flushCanvas();
                 if (pending && submittedSource == null) submittedSource = pendingBase;
                 commitSource();
                 workflow.cancel();
@@ -338,6 +340,8 @@ public final class DesignerPane extends BorderPane implements AutoCloseable {
   private void load(DocumentSnapshot value) {
     if (closed) return;
     loading = true;
+    canvasCommitQueued = false;
+    canvasGeneration++;
     renderSequence.incrementAndGet();
     workflow.cancel();
     try {
@@ -441,6 +445,28 @@ public final class DesignerPane extends BorderPane implements AutoCloseable {
   }
 
   private void canvasChanged() {
+    if (loading || pending || closed || canvasCommitQueued) return;
+    // Kit's corner-resize gesture pushes one job per dimension on the same FX event turn.
+    // Capture the completed gesture, not the intermediate width-only document.
+    canvasCommitQueued = true;
+    long generation = ++canvasGeneration;
+    var projectedDocument = kit.editor().getFxomDocument();
+    var expectedDraft = draft;
+    Platform.runLater(
+        () -> {
+          if (generation != canvasGeneration || closed) return;
+          if (projectedDocument != kit.editor().getFxomDocument() || draft != expectedDraft) {
+            canvasCommitQueued = false;
+            return;
+          }
+          flushCanvas();
+        });
+  }
+
+  private void flushCanvas() {
+    if (!canvasCommitQueued) return;
+    canvasCommitQueued = false;
+    canvasGeneration++;
     if (loading || pending || closed) return;
     try {
       submit(
@@ -454,6 +480,7 @@ public final class DesignerPane extends BorderPane implements AutoCloseable {
 
   private void withDraft(Runnable action) {
     if (document == null) return;
+    flushCanvas();
     if (pending || !source.getText().equals(draft.text())) {
       commitSource();
       status.setText("Finishing source edit; repeat the action when synchronized");
@@ -689,6 +716,7 @@ public final class DesignerPane extends BorderPane implements AutoCloseable {
   }
 
   private void flushInto(CompletableFuture<Void> result, long deadline) {
+    flushCanvas();
     if (System.nanoTime() > deadline) {
       result.completeExceptionally(
           new IllegalStateException("Source edit could not be synchronized"));