Fix export bug when all are invisible

lib/common/data/project/composite_image.dart

@@ -12,6 +12,11 @@ class CompositeImage with EquatableMixin {
   }) : assert(layers
             .every((image) => image.height == height && image.width == width));
 
+  CompositeImage.empty({
+    required this.width,
+    required this.height,
+  }) : layers = [];
+
   final int width;
   final int height;
 

lib/common/data/project/scene.dart

@@ -18,8 +18,8 @@ class Scene extends TimeSpan {
   Iterable<SceneLayer> get visibleLayers =>
       layers.where((layer) => layer.visible);
 
-  int? get frameWidth => layers.first.frameSeq.current.image.width;
-  int? get frameHeight => layers.first.frameSeq.current.image.height;
+  int? get frameWidth => allFrames.first.image.width;
+  int? get frameHeight => allFrames.first.image.height;
 
   /// Visible image at a given playhead position.
   CompositeImage imageAt(Duration playhead) {
@@ -41,6 +41,14 @@ class Scene extends TimeSpan {
 
   /// Frames for export video.
   Iterable<CompositeFrame> getExportFrames() sync* {
+    if (visibleLayers.isEmpty) {
+      yield CompositeFrame(
+        CompositeImage.empty(width: frameWidth!, height: frameHeight!),
+        duration,
+      );
+      return;
+    }
+
     final tracks =
         visibleLayers.map((layer) => layer.getExportFrames(duration)).toList();
 

pubspec.yaml

@@ -15,7 +15,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
 # Read more about iOS versioning at
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
-version: 1.16.1
+version: 1.16.2
 
 environment:
   sdk: '>=2.12.0 <3.0.0'