Minimize patch

src/main/java/dev/kruhlmann/imgfloat/model/AssetPatch.java

@@ -21,9 +21,8 @@ public record AssetPatch(
         Double audioPitch,
         Double audioVolume
 ) {
-    public static AssetPatch fromTransform(Asset asset) {
-        return new AssetPatch(
-                asset.getId(),
+    public static TransformSnapshot capture(Asset asset) {
+        return new TransformSnapshot(
                 asset.getX(),
                 asset.getY(),
                 asset.getWidth(),
@@ -32,7 +31,6 @@ public record AssetPatch(
                 asset.getSpeed(),
                 asset.isMuted(),
                 asset.getZIndex(),
-                null,
                 asset.isAudioLoop(),
                 asset.getAudioDelayMillis(),
                 asset.getAudioSpeed(),
@@ -41,6 +39,30 @@ public record AssetPatch(
         );
     }
 
+    /**
+     * Produces a minimal patch from a transform operation. Only fields that changed and were part of
+     * the incoming request are populated to keep WebSocket payloads small.
+     */
+    public static AssetPatch fromTransform(TransformSnapshot before, Asset asset, TransformRequest request) {
+        return new AssetPatch(
+                asset.getId(),
+                changed(before.x(), asset.getX()),
+                changed(before.y(), asset.getY()),
+                changed(before.width(), asset.getWidth()),
+                changed(before.height(), asset.getHeight()),
+                changed(before.rotation(), asset.getRotation()),
+                request.getSpeed() != null ? changed(before.speed(), asset.getSpeed()) : null,
+                request.getMuted() != null ? changed(before.muted(), asset.isMuted()) : null,
+                request.getZIndex() != null ? changed(before.zIndex(), asset.getZIndex()) : null,
+                null,
+                request.getAudioLoop() != null ? changed(before.audioLoop(), asset.isAudioLoop()) : null,
+                request.getAudioDelayMillis() != null ? changed(before.audioDelayMillis(), asset.getAudioDelayMillis()) : null,
+                request.getAudioSpeed() != null ? changed(before.audioSpeed(), asset.getAudioSpeed()) : null,
+                request.getAudioPitch() != null ? changed(before.audioPitch(), asset.getAudioPitch()) : null,
+                request.getAudioVolume() != null ? changed(before.audioVolume(), asset.getAudioVolume()) : null
+        );
+    }
+
     public static AssetPatch fromVisibility(Asset asset) {
         return new AssetPatch(
                 asset.getId(),
@@ -60,4 +82,32 @@ public record AssetPatch(
                 null
         );
     }
+
+    private static Double changed(double before, double after) {
+        return Double.compare(before, after) == 0 ? null : after;
+    }
+
+    private static Integer changed(int before, int after) {
+        return before == after ? null : after;
+    }
+
+    private static Boolean changed(boolean before, boolean after) {
+        return before == after ? null : after;
+    }
+
+    public record TransformSnapshot(
+            double x,
+            double y,
+            double width,
+            double height,
+            double rotation,
+            double speed,
+            boolean muted,
+            int zIndex,
+            boolean audioLoop,
+            int audioDelayMillis,
+            double audioSpeed,
+            double audioPitch,
+            double audioVolume
+    ) { }
 }

src/main/java/dev/kruhlmann/imgfloat/service/ChannelDirectoryService.java

@@ -214,6 +214,7 @@ public class ChannelDirectoryService {
         return assetRepository.findById(assetId)
                 .filter(asset -> normalized.equals(asset.getBroadcaster()))
                 .map(asset -> {
+                    AssetPatch.TransformSnapshot before = AssetPatch.capture(asset);
                     validateTransform(req);
 
                     asset.setX(req.getX());
@@ -234,9 +235,11 @@ public class ChannelDirectoryService {
                     assetRepository.save(asset);
 
                     AssetView view = AssetView.from(normalized, asset);
-                    AssetPatch patch = AssetPatch.fromTransform(asset);
-                    messagingTemplate.convertAndSend(topicFor(broadcaster),
-                            AssetEvent.updated(broadcaster, patch));
+                    AssetPatch patch = AssetPatch.fromTransform(before, asset, req);
+                    if (hasPatchChanges(patch)) {
+                        messagingTemplate.convertAndSend(topicFor(broadcaster),
+                                AssetEvent.updated(broadcaster, patch));
+                    }
                     return view;
                 });
     }
@@ -357,4 +360,21 @@ public class ChannelDirectoryService {
                 .max()
                 .orElse(0) + 1;
     }
+
+    private boolean hasPatchChanges(AssetPatch patch) {
+        return patch.x() != null
+                || patch.y() != null
+                || patch.width() != null
+                || patch.height() != null
+                || patch.rotation() != null
+                || patch.speed() != null
+                || patch.muted() != null
+                || patch.zIndex() != null
+                || patch.hidden() != null
+                || patch.audioLoop() != null
+                || patch.audioDelayMillis() != null
+                || patch.audioSpeed() != null
+                || patch.audioPitch() != null
+                || patch.audioVolume() != null;
+    }
 }