Add callback for thumbnail loading complete

Fixes sbis04#161

lib/src/trim_viewer/fixed_viewer/fixed_thumbnail_viewer.dart

@@ -11,6 +11,7 @@ class FixedThumbnailViewer extends StatelessWidget {
   final double thumbnailHeight;
   final BoxFit fit;
   final int numberOfThumbnails;
+  final VoidCallback onThumbnailLoadingComplete;
   final int quality;
 
   /// For showing the thumbnails generated from the video,
@@ -22,6 +23,7 @@ class FixedThumbnailViewer extends StatelessWidget {
     required this.thumbnailHeight,
     required this.numberOfThumbnails,
     required this.fit,
+    required this.onThumbnailLoadingComplete,
     this.quality = 75,
   }) : super(key: key);
 
@@ -50,6 +52,9 @@ class FixedThumbnailViewer extends StatelessWidget {
         bytes = lastBytes;
       }
       byteList.add(bytes);
+      if (byteList.length == numberOfThumbnails) {
+        onThumbnailLoadingComplete();
+      }
       yield byteList;
     }
   }

lib/src/trim_viewer/fixed_viewer/fixed_trim_viewer.dart

@@ -60,6 +60,8 @@ class FixedTrimViewer extends StatefulWidget {
   /// Properties for customizing the fixed trim area.
   final FixedTrimAreaProperties areaProperties;
 
+  final VoidCallback onThumbnailLoadingComplete;
+
   /// Widget for displaying the video trimmer.
   ///
   /// This has frame wise preview of the video with a
@@ -107,6 +109,7 @@ class FixedTrimViewer extends StatefulWidget {
   const FixedTrimViewer({
     super.key,
     required this.trimmer,
+    required this.onThumbnailLoadingComplete,
     this.viewerWidth = 50.0 * 8,
     this.viewerHeight = 50,
     this.maxVideoLength = const Duration(milliseconds: 0),
@@ -201,6 +204,7 @@ class _FixedTrimViewerState extends State<FixedTrimViewer>
           thumbnailHeight: _thumbnailViewerH,
           numberOfThumbnails: _numberOfThumbnails,
           quality: widget.areaProperties.thumbnailQuality,
+          onThumbnailLoadingComplete: widget.onThumbnailLoadingComplete,
         );
         this.thumbnailWidget = thumbnailWidget;
         Duration totalDuration = videoPlayerController.value.duration;

lib/src/trim_viewer/scrollable_viewer/scrollable_thumbnail_viewer.dart

@@ -13,6 +13,7 @@ class ScrollableThumbnailViewer extends StatelessWidget {
   final int numberOfThumbnails;
   final int quality;
   final ScrollController scrollController;
+  final VoidCallback onThumbnailLoadingComplete;
 
   /// For showing the thumbnails generated from the video,
   /// like a frame by frame preview
@@ -24,6 +25,7 @@ class ScrollableThumbnailViewer extends StatelessWidget {
     required this.numberOfThumbnails,
     required this.fit,
     required this.scrollController,
+    required this.onThumbnailLoadingComplete,
     this.quality = 75,
   }) : super(key: key);
 
@@ -52,6 +54,9 @@ class ScrollableThumbnailViewer extends StatelessWidget {
         bytes = lastBytes;
       }
       byteList.add(bytes);
+      if (byteList.length == numberOfThumbnails) {
+        onThumbnailLoadingComplete();
+      }
       yield byteList;
     }
   }

lib/src/trim_viewer/scrollable_viewer/scrollable_trim_viewer.dart

@@ -66,6 +66,8 @@ class ScrollableTrimViewer extends StatefulWidget {
   /// Properties for customizing the trim area.
   final TrimAreaProperties areaProperties;
 
+  final VoidCallback onThumbnailLoadingComplete;
+
   /// Widget for displaying the video trimmer.
   ///
   /// This has frame wise preview of the video with a
@@ -114,6 +116,7 @@ class ScrollableTrimViewer extends StatefulWidget {
     super.key,
     required this.trimmer,
     required this.maxVideoLength,
+    required this.onThumbnailLoadingComplete,
     this.viewerWidth = 50 * 8,
     this.viewerHeight = 50,
     this.showDuration = true,
@@ -331,6 +334,7 @@ class _ScrollableTrimViewerState extends State<ScrollableTrimViewer>
           thumbnailHeight: _thumbnailViewerH,
           numberOfThumbnails: _numberOfThumbnails,
           quality: widget.areaProperties.thumbnailQuality,
+          onThumbnailLoadingComplete: widget.onThumbnailLoadingComplete,
         );
         this.thumbnailWidget = thumbnailWidget;
         log('=========================');

lib/src/trim_viewer/trim_viewer.dart

@@ -81,6 +81,10 @@ class TrimViewer extends StatefulWidget {
   /// Properties for customizing the trim area.
   final TrimAreaProperties areaProperties;
 
+  /// Callback for thumbnail loader to know when all the
+  /// thumbnails are loaded.
+  final VoidCallback? onThumbnailLoadingComplete;
+
   /// Widget for displaying the video trimmer.
   ///
   /// This has frame wise preview of the video with a
@@ -154,6 +158,10 @@ class TrimViewer extends StatefulWidget {
   ///
   /// * [areaProperties] defines properties for customizing the trim area.
   ///
+  ///
+  /// * [onThumbnailLoadingComplete] is a callback for thumbnail loader to
+  /// know when all the thumbnails are loaded.
+  ///
   const TrimViewer({
     Key? key,
     required this.trimmer,
@@ -169,6 +177,7 @@ class TrimViewer extends StatefulWidget {
     this.paddingFraction = 0.2,
     this.editorProperties = const TrimEditorProperties(),
     this.areaProperties = const TrimAreaProperties(),
+    this.onThumbnailLoadingComplete,
   }) : super(key: key);
 
   @override
@@ -218,6 +227,11 @@ class _TrimViewerState extends State<TrimViewer> with TickerProviderStateMixin {
       paddingFraction: widget.paddingFraction,
       editorProperties: widget.editorProperties,
       areaProperties: widget.areaProperties,
+      onThumbnailLoadingComplete: () {
+        if (widget.onThumbnailLoadingComplete != null) {
+          widget.onThumbnailLoadingComplete!();
+        }
+      },
     );
 
     final fixedTrimViewer = FixedTrimViewer(
@@ -236,6 +250,11 @@ class _TrimViewerState extends State<TrimViewer> with TickerProviderStateMixin {
         thumbnailQuality: widget.areaProperties.thumbnailQuality,
         borderRadius: widget.areaProperties.borderRadius,
       ),
+      onThumbnailLoadingComplete: () {
+        if (widget.onThumbnailLoadingComplete != null) {
+          widget.onThumbnailLoadingComplete!();
+        }
+      },
     );
 
     return _isScrollableAllowed == null