Merge pull request #329 from Gold872/async_grab

Add async version of VideoCapture.grab()
rainyl · Jan 30, 2025 · 47fec2d · 47fec2d
2 parents 17fc595 + 0f8fe90
commit 47fec2d
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Showing 5 changed files with 19 additions and 5 deletions.
diff --git a/packages/dartcv/CHANGELOG.md b/packages/dartcv/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 1.1.3-WIP
+
+* add `VideoCapture.grabAsync`
+
 ## 1.1.2
 
 * add more functions in `calib3d`

diff --git a/packages/dartcv/lib/src/videoio/videoio.dart b/packages/dartcv/lib/src/videoio/videoio.dart
@@ -82,8 +82,8 @@ class VideoCapture extends CvStruct<cvg.VideoCapture> {
 
   /// Grabs the next frame from video file or capturing device.
   ///
-  /// https://docs.opencv.org/4.x/d8/dfe/classcv_1_1VideoCapture.html#aa6480e6972ef4c00d74814ec841a2939
-  void grab() => cvideoio.cv_VideoCapture_grab(ref, ffi.nullptr);
+  /// https://docs.opencv.org/4.x/d8/dfe/classcv_1_1VideoCapture.html#ae38c2a053d39d6b20c9c649e08ff0146
+  void grab() => cvRun(() => cvideoio.cv_VideoCapture_grab(ref, ffi.nullptr));
 
   (bool, Mat) read({Mat? m}) {
     m ??= Mat.empty();

diff --git a/packages/dartcv/lib/src/videoio/videoio_async.dart b/packages/dartcv/lib/src/videoio/videoio_async.dart
@@ -41,6 +41,14 @@ extension VideoCaptureAsync on VideoCapture {
     );
   }
 
+  /// Grabs the next frame from video file or capturing device.
+  ///
+  /// https://docs.opencv.org/4.x/d8/dfe/classcv_1_1VideoCapture.html#aa6480e6972ef4c00d74814ec841a2939
+  Future<void> grabAsync() => cvRunAsync0(
+        (callback) => cvideoio.cv_VideoCapture_grab(ref, callback),
+        (c) => c.complete(),
+      );
+
   Future<(bool, Mat)> readAsync({Mat? m}) async {
     m ??= Mat.empty();
     final p = calloc<ffi.Bool>();
@@ -196,9 +204,7 @@ extension VideoWriterAsync on VideoWriter {
   Future<void> writeAsync(InputArray image) async {
     return cvRunAsync0(
       (callback) => cvideoio.cv_VideoWriter_write(ref, image.ref, callback),
-      (c) {
-        c.complete();
-      },
+      (c) => c.complete(),
     );
   }
 }
diff --git a/packages/dartcv/test/videoio/videoio_async_test.dart b/packages/dartcv/test/videoio/videoio_async_test.dart
@@ -38,6 +38,8 @@ void main() async {
     expect(frame.isEmpty, false);
     expect(vc.codec, "h264");
 
+    await vc.grabAsync();
+
     expect(cv.VideoCapture.toCodec("h264"), closeTo(875967080, 1e-3));
     // cv.imwrite("cv.VideoCapture.fromFile.png", frame);
   });

diff --git a/packages/dartcv/test/videoio/videoio_test.dart b/packages/dartcv/test/videoio/videoio_test.dart
@@ -50,6 +50,8 @@ void main() async {
     expect(success, true);
     expect(frame.isEmpty, false);
 
+    vc.grab();
+
     expect(vc.getBackendName(), isNotEmpty);
 
     expect(vc.codec, "h264");