From 69b27b246a3f11e775791805eb2c2b4858ed9412 Mon Sep 17 00:00:00 2001
From: MediaPipe Team <mediapipe-team@google.com>
Date: Mon, 5 Dec 2022 14:14:13 -0800
Subject: [PATCH] Adds a public function for creating TaskRunner instances.

PiperOrigin-RevId: 493109736
---
 mediapipe/tasks/web/core/task_runner.ts | 46 ++++++++++++++++---------
 1 file changed, 29 insertions(+), 17 deletions(-)

diff --git a/mediapipe/tasks/web/core/task_runner.ts b/mediapipe/tasks/web/core/task_runner.ts
index d769139bc..e2ab42e31 100644
--- a/mediapipe/tasks/web/core/task_runner.ts
+++ b/mediapipe/tasks/web/core/task_runner.ts
@@ -32,6 +32,34 @@ const GraphRunnerImageLibType =
 /** An implementation of the GraphRunner that supports image operations */
 export class GraphRunnerImageLib extends GraphRunnerImageLibType {}
 
+/**
+ * Creates a new instance of a Mediapipe Task. Determines if SIMD is
+ * supported and loads the relevant WASM binary.
+ * @return A fully instantiated instance of `T`.
+ */
+export async function
+createTaskRunner<T extends TaskRunner<O>, O extends TaskRunnerOptions>(
+    type: WasmMediaPipeConstructor<T>, initializeCanvas: boolean,
+    fileset: WasmFileset, options: O): Promise<T> {
+  const fileLocator: FileLocator = {
+    locateFile() {
+      // The only file loaded with this mechanism is the Wasm binary
+      return fileset.wasmBinaryPath.toString();
+    }
+  };
+
+  // Initialize a canvas if requested. If OffscreenCanvas is availble, we
+  // let the graph runner initialize it by passing `undefined`.
+  const canvas = initializeCanvas ? (typeof OffscreenCanvas === 'undefined' ?
+                                         document.createElement('canvas') :
+                                         undefined) :
+                                    null;
+  const instance = await createMediaPipeLib(
+      type, fileset.wasmLoaderPath, NO_ASSETS, canvas, fileLocator);
+  await instance.setOptions(options);
+  return instance;
+}
+
 /** Base class for all MediaPipe Tasks. */
 export abstract class TaskRunner<O extends TaskRunnerOptions> {
   protected abstract baseOptions: BaseOptionsProto;
@@ -47,23 +75,7 @@ export abstract class TaskRunner<O extends TaskRunnerOptions> {
                                                   O extends TaskRunnerOptions>(
       type: WasmMediaPipeConstructor<T>, initializeCanvas: boolean,
       fileset: WasmFileset, options: O): Promise<T> {
-    const fileLocator: FileLocator = {
-      locateFile() {
-        // The only file loaded with this mechanism is the Wasm binary
-        return fileset.wasmBinaryPath.toString();
-      }
-    };
-
-    // Initialize a canvas if requested. If OffscreenCanvas is availble, we
-    // let the graph runner initialize it by passing `undefined`.
-    const canvas = initializeCanvas ? (typeof OffscreenCanvas === 'undefined' ?
-                                           document.createElement('canvas') :
-                                           undefined) :
-                                      null;
-    const instance = await createMediaPipeLib(
-        type, fileset.wasmLoaderPath, NO_ASSETS, canvas, fileLocator);
-    await instance.setOptions(options);
-    return instance;
+    return createTaskRunner(type, initializeCanvas, fileset, options);
   }
 
   constructor(