[Modify]修改async_uil中interval实现

lib/utils/async_typeof.dart

@@ -2,6 +2,8 @@ import 'dart:async';
 
 typedef FutureCallback<T> = Future<T> Function();
 
+typedef IntervalCallback<T> = Future<T> Function(int times);
+
 typedef Cancelable<T> = void Function();
 
 typedef FutureCompleter<T> = void Function(Completer<T> completer);

lib/utils/async_util.dart

@@ -1,7 +1,5 @@
 import 'dart:async';
 
-import 'package:flutter/widgets.dart';
-
 import 'async_typeof.dart';
 import 'cancel_future.dart';
 
@@ -105,37 +103,34 @@ class AsyncUtil {
     });
   }
 
-  ///实际delay第一次执行的时间为delay+interval
-  static CancelableFuture<T> interval<T>(FutureCallback<T> callback,
-      Duration delay, Duration interval, int times) {
+  static StreamController<T> interval<T>(
+      IntervalCallback<T> callback, Duration interval, int times,
+      {Duration? delay}) {
     Timer? timer;
-    Timer? delayTimer;
-    int counter = 0;
-
-    void tick(Completer<T> completer) {
-      if (counter < times) {
-        callback().then((value) {
-          if (!completer.isCompleted) {
-            completer.complete(value);
-          }
-        }).catchError((error) {
-          if (!completer.isCompleted) {
-            completer.completeError(error);
-          }
-        });
-        counter++;
-      } else {
-        timer?.cancel();
-      }
-    }
-
-    return CancelableFuture<T>((completer) {
-      delayTimer = Timer(delay, () {
-        timer = Timer.periodic(interval, (Timer t) => tick(completer));
-      });
-    }, () {
-      delayTimer?.cancel();
+    StreamController<T> controller = StreamController<T>(onCancel: () {
       timer?.cancel();
     });
+    int count = 0;
+    void tick() {
+      callback(count).then((value) {
+        controller.add(value);
+        count++;
+        if (count < times) {
+          timer = Timer(interval, tick);
+        } else {
+          controller.close();
+        }
+      }).catchError((error) {
+        controller.addError(error);
+        controller.close();
+      });
+    }
+
+    if (delay != null && delay > Duration.zero) {
+      timer = Timer(delay, tick);
+    } else {
+      tick();
+    }
+    return controller;
   }
 }