comments

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm

@@ -566,11 +566,9 @@ static bool ClipRRectContainsPlatformViewBoundingRect(const SkRRect& clip_rrect,
 
   CGFloat screenScale = [UIScreen mainScreen].scale;
   // The UIKit frame is set based on the logical resolution (points) instead of physical.
-  //
   // (https://developer.apple.com/library/archive/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Displays/Displays.html).
   // However, flow is based on the physical resolution. For example, 1000 pixels in flow equals
-  // 500 points in UIKit for devices that has screenScale of 2. We need to scale the
-  // transformMatrix
+  // 500 points in UIKit for devices that has screenScale of 2. We need to scale the transformMatrix
   // down to the logical resoltion before applying it to the layer of PlatformView.
   transformMatrix.postScale(1 / screenScale, 1 / screenScale);
 
@@ -579,13 +577,11 @@ static bool ClipRRectContainsPlatformViewBoundingRect(const SkRRect& clip_rrect,
   // Thus, this translate needs to be reversed so the platform view can layout at the correct
   // offset.
   //
-  // Note that the transforms are not applied to the clipping paths because clipping paths happen
-  // on
+  // Note that the transforms are not applied to the clipping paths because clipping paths happen on
   // the mask view, whose origin is always (0,0) to the flutter_view.
   transformMatrix.postTranslate(-clipView.frame.origin.x, -clipView.frame.origin.y);
 
   embedded_view.layer.transform = flutter::GetCATransform3DFromSkMatrix(transformMatrix);
-  // embedded_view.frame = clipView.bounds;
 }
 
 void FlutterPlatformViewsController::CompositeWithParams(int view_id,
@@ -911,7 +907,6 @@ static bool ClipRRectContainsPlatformViewBoundingRect(const SkRRect& clip_rrect,
   if (catransaction_added_) {
     FML_DCHECK([[NSThread currentThread] isMainThread]);
     [CATransaction commit];
-
     catransaction_added_ = false;
   }
 }

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h

@@ -51,14 +51,22 @@
 
 // A pool that provides |FlutterClippingMaskView|s.
 //
-// Allocation and deallocation of |FlutterClippingMaskView| is minimized while using the pool.
+// The pool has a capacity that can be set in the initializer.
+// When requesting a FlutterClippingMaskView, the pool will first try to reuse an available maskView
+// in the pool. If there are none available, a new FlutterClippingMaskView is constructed. If the
+// capacity is reached, the newly constructed FlutterClippingMaskView is not added to the pool.
+//
+// Call |recycleMaskViews| to mark all the FlutterClippingMaskViews in the pool available.
 @interface FlutterClippingMaskViewPool : NSObject
 
+// Initialize the pool with `capacity`. When the `capacity` is reached, a FlutterClippingMaskView is
+// constructed when requested, and it is not added to the pool.
 - (instancetype)initWithCapacity:(NSInteger)capacity;
 
 // Reuse a maskView from the pool, or allocate a new one.
 - (FlutterClippingMaskView*)getMaskViewWithFrame:(CGRect)frame;
 
+// Mark all the maskViews available.
 - (void)recycleMaskViews;
 
 @end

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.mm

@@ -456,6 +456,7 @@ @interface FlutterClippingMaskViewPool ()
 
 @property(assign, nonatomic) NSUInteger capacity;
 @property(retain, nonatomic) NSMutableArray<FlutterClippingMaskView*>* pool;
+// The index points to the first available FlutterClippingMaskView in the `pool`.
 @property(assign, nonatomic) NSUInteger availableIndex;
 
 @end
@@ -471,7 +472,6 @@ - (instancetype)initWithCapacity:(NSInteger)capacity {
   return self;
 }
 
-// Reuse a maskView from the pool, or allocate a new one.
 - (FlutterClippingMaskView*)getMaskViewWithFrame:(CGRect)frame {
   FML_DCHECK(self.availableIndex <= self.capacity);
   FlutterClippingMaskView* maskView;