minor fixes

Author: zhuxingwei

com.unity.uiwidgets/Runtime/rendering/flow.cs

@@ -8,9 +8,9 @@ public interface FlowPaintingContext {
 
         int childCount { get; }
 
-        public Size getChildSize(int i);
+        Size getChildSize(int i);
 
-        public void paintChild(int i, Matrix4 transform = null, float opacity = 1.0f);
+        void paintChild(int i, Matrix4 transform = null, float opacity = 1.0f);
     }
 
     public abstract class FlowDelegate {
@@ -161,7 +161,7 @@ public Size getChildSize(int i) {
         }
 
         public void paintChild(int i, Matrix4 transform = null, float opacity = 1.0f) {
-            transform ??= Matrix4.identity();
+            transform = transform ?? Matrix4.identity();
             RenderBox child = _randomAccessChildren[i];
             FlowParentData childParentData = child.parentData as FlowParentData;
             D.assert(() => {
@@ -233,8 +233,8 @@ protected override bool hitTestChildren(BoxHitTestResult result, Offset position
                 bool absorbed = result.addWithPaintTransform(
                     transform: transform,
                     position: position,
-                    hitTest: (BoxHitTestResult result, Offset position) => {
-                        return child.hitTest(result, position: position);
+                    hitTest: (BoxHitTestResult result2, Offset position2) => {
+                        return child.hitTest(result2, position: position2);
                     }
                 );
                 if (absorbed)

com.unity.uiwidgets/Runtime/rendering/proxy_box.cs

@@ -762,16 +762,18 @@ public void _updateOpacity() {
         public override void paint(PaintingContext context, Offset offset) {
             if (child != null) {
                 if (_alpha == 0) {
+                    layer = null;
                     return;
                 }
 
                 if (_alpha == 255) {
+                    layer = null;
                     context.paintChild(child, offset);
                     return;
                 }
-
+                
                 D.assert(needsCompositing);
-                context.pushOpacity(offset, _alpha, base.paint);
+                layer = context.pushOpacity(offset, _alpha, base.paint, layer as OpacityLayer);
             }
         }