Make delegate sticky

PiperOrigin-RevId: 513249729

mediapipe/tasks/web/core/BUILD

@@ -56,6 +56,7 @@ mediapipe_ts_library(
     deps = [
         ":core",
         ":task_runner",
+        "//mediapipe/calculators/tensor:inference_calculator_jspb_proto",
         "//mediapipe/tasks/cc/core/proto:base_options_jspb_proto",
         "//mediapipe/web/graph_runner:graph_runner_ts",
     ],

mediapipe/tasks/web/core/task_runner.ts

@@ -208,13 +208,23 @@ export abstract class TaskRunner {
 
   /** Configures the `acceleration` option. */
   private setAcceleration(options: BaseOptions) {
-    const acceleration =
-        this.baseOptions.getAcceleration() ?? new Acceleration();
+    let acceleration = this.baseOptions.getAcceleration();
+
+    if (!acceleration) {
+      // Create default instance for the initial configuration.
+      acceleration = new Acceleration();
+      acceleration.setTflite(new InferenceCalculatorOptions.Delegate.TfLite());
+    }
+
+    if ('delegate' in options) {
       if (options.delegate === 'GPU') {
         acceleration.setGpu(new InferenceCalculatorOptions.Delegate.Gpu());
       } else {
-      acceleration.setTflite(new InferenceCalculatorOptions.Delegate.TfLite());
+        acceleration.setTflite(
+            new InferenceCalculatorOptions.Delegate.TfLite());
       }
+    }
+
     this.baseOptions.setAcceleration(acceleration);
   }
 }

mediapipe/tasks/web/core/task_runner_test.ts

@@ -16,6 +16,7 @@
 import 'jasmine';
 
 // Placeholder for internal dependency on encodeByteArray
+import {InferenceCalculatorOptions} from '../../../calculators/tensor/inference_calculator_pb';
 import {BaseOptions as BaseOptionsProto} from '../../../tasks/cc/core/proto/base_options_pb';
 import {TaskRunner} from '../../../tasks/web/core/task_runner';
 import {ErrorListener} from '../../../web/graph_runner/graph_runner';
@@ -97,6 +98,23 @@ describe('TaskRunner', () => {
       tflite: {},
     },
   };
+  const mockBytesResultWithGpuDelegate = {
+    ...mockBytesResult,
+    acceleration: {
+      xnnpack: undefined,
+      gpu: {
+        useAdvancedGpuApi: false,
+        api: InferenceCalculatorOptions.Delegate.Gpu.Api.ANY,
+        allowPrecisionLoss: true,
+        cachedKernelPath: undefined,
+        serializedModelDir: undefined,
+        modelToken: undefined,
+        usage: InferenceCalculatorOptions.Delegate.Gpu.InferenceUsage
+                   .SUSTAINED_SPEED,
+      },
+      tflite: undefined,
+    },
+  };
 
   let fetchSpy: jasmine.Spy;
   let taskRunner: TaskRunnerFake;
@@ -224,22 +242,8 @@ describe('TaskRunner', () => {
         delegate: 'GPU',
       }
     });
-    expect(taskRunner.baseOptions.toObject()).toEqual({
-      ...mockBytesResult,
-      acceleration: {
-        xnnpack: undefined,
-        gpu: {
-          useAdvancedGpuApi: false,
-          api: 0,
-          allowPrecisionLoss: true,
-          cachedKernelPath: undefined,
-          serializedModelDir: undefined,
-          modelToken: undefined,
-          usage: 2,
-        },
-        tflite: undefined,
-      },
-    });
+    expect(taskRunner.baseOptions.toObject())
+        .toEqual(mockBytesResultWithGpuDelegate);
   });
 
   it('can reset delegate', async () => {
@@ -249,8 +253,20 @@ describe('TaskRunner', () => {
         delegate: 'GPU',
       }
     });
-    // Clear backend
+    // Clear delegate
     await taskRunner.setOptions({baseOptions: {delegate: undefined}});
     expect(taskRunner.baseOptions.toObject()).toEqual(mockBytesResult);
   });
+
+  it('keeps delegate if not provided', async () => {
+    await taskRunner.setOptions({
+      baseOptions: {
+        modelAssetBuffer: new Uint8Array(mockBytes),
+        delegate: 'GPU',
+      }
+    });
+    await taskRunner.setOptions({baseOptions: {}});
+    expect(taskRunner.baseOptions.toObject())
+        .toEqual(mockBytesResultWithGpuDelegate);
+  });
 });