Add fp16 option for NNAPI in Android classification example

lite/examples/image_classification/android/app/src/main/java/org/tensorflow/lite/examples/classification/CameraActivity.java

@@ -43,9 +43,11 @@
 import android.view.ViewTreeObserver;
 import android.view.WindowManager;
 import android.widget.AdapterView;
+import android.widget.CompoundButton;
 import android.widget.ImageView;
 import android.widget.LinearLayout;
 import android.widget.Spinner;
+import android.widget.Switch;
 import android.widget.TextView;
 import android.widget.Toast;
 import com.google.android.material.bottomsheet.BottomSheetBehavior;
@@ -61,7 +63,7 @@ public abstract class CameraActivity extends AppCompatActivity
     implements OnImageAvailableListener,
         Camera.PreviewCallback,
         View.OnClickListener,
-        AdapterView.OnItemSelectedListener {
+        AdapterView.OnItemSelectedListener, Switch.OnCheckedChangeListener {
   private static final Logger LOGGER = new Logger();
 
   private static final int PERMISSIONS_REQUEST = 1;
@@ -97,10 +99,12 @@ public abstract class CameraActivity extends AppCompatActivity
   private Spinner modelSpinner;
   private Spinner deviceSpinner;
   private TextView threadsTextView;
+  private Switch fp16Switch;
 
   private Model model = Model.QUANTIZED_EFFICIENTNET;
   private Device device = Device.CPU;
   private int numThreads = -1;
+  private boolean allowFP16 = false;
 
   @Override
   protected void onCreate(final Bundle savedInstanceState) {
@@ -116,6 +120,7 @@ protected void onCreate(final Bundle savedInstanceState) {
       requestPermission();
     }
 
+    fp16Switch = findViewById(R.id.fp16);
     threadsTextView = findViewById(R.id.threads);
     plusImageView = findViewById(R.id.plus);
     minusImageView = findViewById(R.id.minus);
@@ -192,9 +197,13 @@ public void onSlide(@NonNull View bottomSheet, float slideOffset) {}
     plusImageView.setOnClickListener(this);
     minusImageView.setOnClickListener(this);
 
+    fp16Switch.setOnCheckedChangeListener(this);
+
     model = Model.valueOf(modelSpinner.getSelectedItem().toString().toUpperCase());
     device = Device.valueOf(deviceSpinner.getSelectedItem().toString());
     numThreads = Integer.parseInt(threadsTextView.getText().toString().trim());
+    allowFP16 = fp16Switch.isChecked();
+    fp16Switch.setEnabled(false);
   }
 
   protected int[] getRgbBytes() {
@@ -577,6 +586,7 @@ private void setModel(Model model) {
     if (this.model != model) {
       LOGGER.d("Updating  model: " + model);
       this.model = model;
+      fp16Switch.setEnabled(((model == Model.FLOAT_MOBILENET) || (model == Model.FLOAT_EFFICIENTNET)) && (device == Device.NNAPI));
       onInferenceConfigurationChanged();
     }
   }
@@ -593,6 +603,7 @@ private void setDevice(Device device) {
       plusImageView.setEnabled(threadsEnabled);
       minusImageView.setEnabled(threadsEnabled);
       threadsTextView.setText(threadsEnabled ? String.valueOf(numThreads) : "N/A");
+      fp16Switch.setEnabled(((model == Model.FLOAT_MOBILENET) || (model == Model.FLOAT_EFFICIENTNET)) && (device == Device.NNAPI));
       onInferenceConfigurationChanged();
     }
   }
@@ -609,6 +620,8 @@ private void setNumThreads(int numThreads) {
     }
   }
 
+  protected boolean getFP16() { return allowFP16; }
+
   protected abstract void processImage();
 
   protected abstract void onPreviewSizeChosen(final Size size, final int rotation);
@@ -651,4 +664,10 @@ public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
   public void onNothingSelected(AdapterView<?> parent) {
     // Do nothing.
   }
+
+  @Override
+  public void onCheckedChanged(CompoundButton switchView, boolean isChecked) {
+    allowFP16 = isChecked;
+    onInferenceConfigurationChanged();
+  }
 }

lite/examples/image_classification/android/app/src/main/java/org/tensorflow/lite/examples/classification/ClassifierActivity.java

@@ -64,7 +64,7 @@ public void onPreviewSizeChosen(final Size size, final int rotation) {
     borderedText = new BorderedText(textSizePx);
     borderedText.setTypeface(Typeface.MONOSPACE);
 
-    recreateClassifier(getModel(), getDevice(), getNumThreads());
+    recreateClassifier(getModel(), getDevice(), getNumThreads(), getFP16());
     if (classifier == null) {
       LOGGER.e("No classifier on preview!");
       return;
@@ -83,6 +83,8 @@ public void onPreviewSizeChosen(final Size size, final int rotation) {
   @Override
   protected void processImage() {
     rgbFrameBitmap.setPixels(getRgbBytes(), 0, previewWidth, 0, 0, previewWidth, previewHeight);
+    final int imageSizeX = (classifier == null) ? 224 : classifier.getImageSizeX();
+    final int imageSizeY = (classifier == null) ? 224 : classifier.getImageSizeY();
     final int cropSize = Math.min(previewWidth, previewHeight);
 
     runInBackground(
@@ -123,10 +125,11 @@ protected void onInferenceConfigurationChanged() {
     final Device device = getDevice();
     final Model model = getModel();
     final int numThreads = getNumThreads();
-    runInBackground(() -> recreateClassifier(model, device, numThreads));
+    final boolean fp16 = getFP16();
+    runInBackground(() -> recreateClassifier(model, device, numThreads, fp16));
   }
 
-  private void recreateClassifier(Model model, Device device, int numThreads) {
+  private void recreateClassifier(Model model, Device device, int numThreads, boolean fp16) {
     if (classifier != null) {
       LOGGER.d("Closing classifier.");
       classifier.close();
@@ -143,8 +146,8 @@ private void recreateClassifier(Model model, Device device, int numThreads) {
     }
     try {
       LOGGER.d(
-          "Creating classifier (model=%s, device=%s, numThreads=%d)", model, device, numThreads);
-      classifier = Classifier.create(this, model, device, numThreads);
+          "Creating classifier (model=%s, device=%s, numThreads=%d, allowFP16=%b)", model, device, numThreads, fp16);
+      classifier = Classifier.create(this, model, device, numThreads, fp16);
     } catch (IOException e) {
       LOGGER.e(e, "Failed to create classifier.");
     }

lite/examples/image_classification/android/app/src/main/java/org/tensorflow/lite/examples/classification/tflite/Classifier.java

@@ -107,16 +107,17 @@ public enum Device {
    * @param model The model to use for classification.
    * @param device The device to use for classification.
    * @param numThreads The number of threads to use for classification.
+   * @param fp16 Allow FP32 model to run on FP16 accelerators
    * @return A classifier with the desired configuration.
    */
-  public static Classifier create(Activity activity, Model model, Device device, int numThreads)
+  public static Classifier create(Activity activity, Model model, Device device, int numThreads, boolean fp16)
       throws IOException {
     if (model == Model.QUANTIZED_MOBILENET) {
       return new ClassifierQuantizedMobileNet(activity, device, numThreads);
     } else if (model == Model.FLOAT_MOBILENET) {
-      return new ClassifierFloatMobileNet(activity, device, numThreads);
+      return new ClassifierFloatMobileNet(activity, device, numThreads, fp16);
     } else if (model == Model.FLOAT_EFFICIENTNET) {
-      return new ClassifierFloatEfficientNet(activity, device, numThreads);
+      return new ClassifierFloatEfficientNet(activity, device, numThreads, fp16);
     } else if (model == Model.QUANTIZED_EFFICIENTNET) {
       return new ClassifierQuantizedEfficientNet(activity, device, numThreads);
     } else {
@@ -195,12 +196,13 @@ public String toString() {
   }
 
   /** Initializes a {@code Classifier}. */
-  protected Classifier(Activity activity, Device device, int numThreads) throws IOException {
+  protected Classifier(Activity activity, Device device, int numThreads, boolean fp16) throws IOException {
     tfliteModel = FileUtil.loadMappedFile(activity, getModelPath());
     switch (device) {
       case NNAPI:
         nnApiDelegate = new NnApiDelegate();
         tfliteOptions.addDelegate(nnApiDelegate);
+        tfliteOptions.setAllowFp16PrecisionForFp32(fp16);
         break;
       case GPU:
         gpuDelegate = new GpuDelegate();

lite/examples/image_classification/android/app/src/main/java/org/tensorflow/lite/examples/classification/tflite/ClassifierFloatEfficientNet.java

@@ -40,9 +40,9 @@ public class ClassifierFloatEfficientNet extends Classifier {
    *
    * @param activity
    */
-  public ClassifierFloatEfficientNet(Activity activity, Device device, int numThreads)
+  public ClassifierFloatEfficientNet(Activity activity, Device device, int numThreads, boolean fp16)
       throws IOException {
-    super(activity, device, numThreads);
+    super(activity, device, numThreads, fp16);
   }
 
   @Override

lite/examples/image_classification/android/app/src/main/java/org/tensorflow/lite/examples/classification/tflite/ClassifierFloatMobileNet.java

@@ -42,9 +42,9 @@ public class ClassifierFloatMobileNet extends Classifier {
    *
    * @param activity
    */
-  public ClassifierFloatMobileNet(Activity activity, Device device, int numThreads)
+  public ClassifierFloatMobileNet(Activity activity, Device device, int numThreads, boolean fp16)
       throws IOException {
-    super(activity, device, numThreads);
+    super(activity, device, numThreads, fp16);
   }
 
   @Override

lite/examples/image_classification/android/app/src/main/java/org/tensorflow/lite/examples/classification/tflite/ClassifierQuantizedEfficientNet.java

@@ -43,7 +43,7 @@ public class ClassifierQuantizedEfficientNet extends Classifier {
    */
   public ClassifierQuantizedEfficientNet(Activity activity, Device device, int numThreads)
       throws IOException {
-    super(activity, device, numThreads);
+    super(activity, device, numThreads, /*fp16=*/ false);
   }
 
   @Override

lite/examples/image_classification/android/app/src/main/java/org/tensorflow/lite/examples/classification/tflite/ClassifierQuantizedMobileNet.java

@@ -44,7 +44,7 @@ public class ClassifierQuantizedMobileNet extends Classifier {
    */
   public ClassifierQuantizedMobileNet(Activity activity, Device device, int numThreads)
       throws IOException {
-    super(activity, device, numThreads);
+    super(activity, device, numThreads, /*fp16=*/ false);
   }
 
   @Override

lite/examples/image_classification/android/app/src/main/res/layout/tfe_ic_layout_bottom_sheet.xml

@@ -224,6 +224,12 @@
         android:layout_marginTop="10dp"
         android:background="@android:color/darker_gray" />
 
+    <Switch
+        android:id="@+id/fp16"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="AllowFP16" />
+
     <RelativeLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"