Merge pull request #168 from abdelaziz-mahdy/imencode

fix imencode interface
rainyl · Jul 22, 2024 · 4bbed3f · 4bbed3f
2 parents 2bfb3b2 + 3cf58cc
commit 4bbed3f
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Showing 3 changed files with 30 additions and 20 deletions.
diff --git a/example/lib/main.dart b/example/lib/main.dart
@@ -33,14 +33,15 @@ class _MyAppState extends State<MyApp> {
   }
 
   // native resources are unsendable for isolate, so use raw data or encoded Uint8List and convert back
-  Future<(Uint8List, Uint8List)> heavyTask(Uint8List buffer) async => Isolate.run(() {
+  Future<(Uint8List, Uint8List)> heavyTask(Uint8List buffer) async =>
+      Isolate.run(() {
         final im = cv.imdecode(buffer, cv.IMREAD_COLOR);
         late cv.Mat gray, blur;
         for (var i = 0; i < 1000; i++) {
           gray = cv.cvtColor(im, cv.COLOR_BGR2GRAY);
           blur = cv.gaussianBlur(im, (7, 7), 2, sigmaY: 2);
         }
-        return (cv.imencode(".png", gray), cv.imencode(".png", blur));
+        return (cv.imencode(".png", gray).$2, cv.imencode(".png", blur).$2);
       });
 
   Future<(cv.Mat, cv.Mat)> heavyTaskAsync(cv.Mat im) async {
@@ -66,12 +67,14 @@ class _MyAppState extends State<MyApp> {
               ElevatedButton(
                 onPressed: () async {
                   final picker = ImagePicker();
-                  final img = await picker.pickImage(source: ImageSource.gallery);
+                  final img =
+                      await picker.pickImage(source: ImageSource.gallery);
                   if (img != null) {
                     final path = img.path;
                     final mat = cv.imread(path);
-                    print("cv.imread: width: ${mat.cols}, height: ${mat.rows}, path: $path");
-                    final bytes = cv.imencode(".png", mat);
+                    print(
+                        "cv.imread: width: ${mat.cols}, height: ${mat.rows}, path: $path");
+                    final (success, bytes) = cv.imencode(".png", mat);
                     // heavy computation
                     final (gray, blur) = await heavyTask(bytes);
                     setState(() {
@@ -83,16 +86,22 @@ class _MyAppState extends State<MyApp> {
               ),
               ElevatedButton(
                 onPressed: () async {
-                  final data = await DefaultAssetBundle.of(context).load("images/lenna.png");
+                  final data = await DefaultAssetBundle.of(context)
+                      .load("images/lenna.png");
                   final bytes = data.buffer.asUint8List();
                   // heavy computation
                   // final (gray, blur) = await heavyTask(bytes);
                   // setState(() {
                   //   images = [bytes, gray, blur];
                   // });
-                  final (gray, blur) = await heavyTaskAsync(cv.imdecode(bytes, cv.IMREAD_COLOR));
+                  final (gray, blur) =
+                      await heavyTaskAsync(cv.imdecode(bytes, cv.IMREAD_COLOR));
                   setState(() {
-                    images = [bytes, cv.imencode(".png", gray), cv.imencode(".png", blur)];
+                    images = [
+                      bytes,
+                      cv.imencode(".png", gray).$2,
+                      cv.imencode(".png", blur).$2
+                    ];
                   });
                 },
                 child: const Text("Process"),

diff --git a/lib/src/imgcodecs/imgcodecs.dart b/lib/src/imgcodecs/imgcodecs.dart
@@ -6,8 +6,6 @@ import 'dart:typed_data';
 import 'package:ffi/ffi.dart';
 
 import '../core/base.dart';
-import '../core/error_code.dart';
-import '../core/exception.dart';
 import '../core/mat.dart';
 import '../core/vec.dart';
 import '../g/constants.g.dart';
@@ -59,23 +57,26 @@ bool imwrite(String filename, InputArray img, {VecI32? params}) {
 ///
 /// For further details, please see:
 /// http://docs.opencv.org/master/d4/da8/group__imgcodecs.html#ga461f9ac09887e47797a54567df3b8b63
-Uint8List imencode(
+(bool, Uint8List) imencode(
   String ext,
   InputArray img, {
   VecI32? params,
 }) {
   final buffer = calloc<cvg.VecUChar>();
-  final success = calloc<ffi.Bool>();
+  final pSuccess = calloc<ffi.Bool>();
   final cExt = ext.toNativeUtf8().cast<ffi.Char>();
 
   params == null
-      ? cvRun(() => cimgcodecs.Image_IMEncode(cExt, img.ref, success, buffer))
-      : cvRun(() => cimgcodecs.Image_IMEncode_WithParams(cExt, img.ref, params.ref, success, buffer));
+      ? cvRun(() => cimgcodecs.Image_IMEncode(cExt, img.ref, pSuccess, buffer))
+      : cvRun(() => cimgcodecs.Image_IMEncode_WithParams(cExt, img.ref, params.ref, pSuccess, buffer));
+  final success = pSuccess.value;
   calloc.free(cExt);
-  if (!success.value) {
-    throw CvException(ErrorCode.StsError.code, msg: "imencode failed, check your params");
-  }
-  return VecUChar.fromPointer(buffer).toU8List();
+  calloc.free(pSuccess);
+
+  final vec = VecUChar.fromPointer(buffer);
+  final u8List = vec.toU8List(); // will copy data
+  vec.dispose();
+  return (success, u8List);
 }
 
 /// imdecode reads an image from a buffer in memory.

diff --git a/test/imgcodecs_test.dart b/test/imgcodecs_test.dart
@@ -26,11 +26,11 @@ void main() async {
   test("cv2.imencode, cv2.imdecode", () async {
     final cvImage = cv.imread("test/images/circles.jpg", flags: cv.IMREAD_COLOR);
     expect((cvImage.width, cvImage.height), (512, 512));
-    final buf = cv.imencode(".png", cvImage);
+    final (success, buf) = cv.imencode(".png", cvImage);
     expect(buf.length, greaterThan(0));
     await File("test/images_out/test_imencode.png").writeAsBytes(buf);
     final params = [cv.IMWRITE_PNG_COMPRESSION, 9].i32;
-    final buf1 = cv.imencode(".png", cvImage, params: params);
+    final (success1, buf1) = cv.imencode(".png", cvImage, params: params);
     expect(buf1.length, greaterThan(0));
 
     final cvimgDecode = cv.imdecode(buf, cv.IMREAD_COLOR);