From 8ec3732c430d7889c3f9b8a5aa618262eec18fc7 Mon Sep 17 00:00:00 2001
From: EddyVerbruggen <eddyverbruggen@gmail.com>
Date: Thu, 10 May 2018 23:22:22 +0200
Subject: [PATCH] #699 Add ML Kit support

---
 demo/app/app.css                              |   3 +-
 demo/app/main-page.ts                         |  28 +-
 demo/app/main-page.xml                        |  27 +-
 .../Android/src/main/AndroidManifest.xml      |   2 +-
 .../barcodescanning/barcodescanning-common.ts |   8 +-
 src/mlkit/barcodescanning/index.android.ts    | 344 ++----------------
 src/mlkit/barcodescanning/index.d.ts          |   6 +-
 src/mlkit/barcodescanning/index.ios.ts        |  56 +--
 .../facedetection/facedetection-common.ts     |  32 ++
 src/mlkit/facedetection/index.android.ts      | 106 ++++++
 src/mlkit/facedetection/index.d.ts            |  20 +
 src/mlkit/index.ts                            |  15 +-
 src/mlkit/mlkit-cameraview.android.ts         | 312 ++++++++++++++++
 src/mlkit/mlkit-cameraview.ios.ts             |   0
 src/mlkit/textrecognition/index.d.ts          |   3 +-
 15 files changed, 571 insertions(+), 391 deletions(-)
 create mode 100644 src/mlkit/facedetection/facedetection-common.ts
 create mode 100644 src/mlkit/facedetection/index.android.ts
 create mode 100644 src/mlkit/facedetection/index.d.ts
 create mode 100644 src/mlkit/mlkit-cameraview.android.ts
 create mode 100644 src/mlkit/mlkit-cameraview.ios.ts

diff --git a/demo/app/app.css b/demo/app/app.css
index e7394b8a..81e53074 100644
--- a/demo/app/app.css
+++ b/demo/app/app.css
@@ -82,8 +82,7 @@ button {
 }
 
 .barcodescanner {
-  width: 320;
-  height: 260;
+  height: 420;
   margin-top: 16;
 }
 
diff --git a/demo/app/main-page.ts b/demo/app/main-page.ts
index 6b679cee..e425b747 100644
--- a/demo/app/main-page.ts
+++ b/demo/app/main-page.ts
@@ -3,6 +3,7 @@ import * as pages from 'tns-core-modules/ui/page';
 import { HelloWorldModel } from './main-view-model';
 import { MLKitRecognizeTextResult } from "nativescript-plugin-firebase/mlkit/textrecognition";
 import { MLKitScanBarcodesResult } from "nativescript-plugin-firebase/mlkit/barcodescanning";
+import { MLKitDetectFacesResult } from "nativescript-plugin-firebase/mlkit/facedetection";
 
 const model = new HelloWorldModel();
 
@@ -24,5 +25,30 @@ export function onBarcodesScanResult(scanResult: any) {
 
 export function onTextRecognitionResult(scanResult: any) {
   const value: MLKitRecognizeTextResult = scanResult.value;
-  model.set("textValue", value.features.map(feature => feature.text).join("\n"));
+  model.set("textValue", value.features.map(feature => feature.text).join("\n\n"));
+}
+
+export function onFaceDetectionResult(scanResult: any) {
+  const value: MLKitDetectFacesResult = scanResult.value;
+  if (value.faces.length > 0) {
+    let allSmilingAndEyesOpen = true;
+    value.faces.forEach(face => {
+      allSmilingAndEyesOpen = allSmilingAndEyesOpen && face.smilingProbability && face.leftEyeOpenProbability && face.rightEyeOpenProbability &&
+          face.smilingProbability > 0.7 && face.leftEyeOpenProbability > 0.7 && face.rightEyeOpenProbability > 0.7;
+    });
+    model.set("allOK", `All smiling and eyes open? ${allSmilingAndEyesOpen ? 'Yes, screen grabbed:' : 'Nope. Sad.'}`);
+    // model.set("textValue", value.faces.map(face => JSON.stringify(face)).join("\n"));
+    model.set("textValue", value.faces.map(face => `Smiling? ${round(face.smilingProbability)}%\nLeft eye open? ${round(face.leftEyeOpenProbability)}%\nRight eye open? ${round(face.rightEyeOpenProbability)}%`).join("\n\n"));
+
+    if (allSmilingAndEyesOpen && value.imageSource) {
+      model.set("lastMatch", value.imageSource);
+    }
+  }
+}
+
+function round (input) {
+  if (isNaN(input)) {
+    return 0;
+  }
+  return Math.round(input * 100);
 }
diff --git a/demo/app/main-page.xml b/demo/app/main-page.xml
index 34c88e19..d73f8ae6 100644
--- a/demo/app/main-page.xml
+++ b/demo/app/main-page.xml
@@ -1,4 +1,8 @@
-<TabView loaded="pageLoaded" class="page" xmlns:FirebaseMLKitBarcodeScanning="nativescript-plugin-firebase/mlkit/barcodescanning">
+<TabView
+    loaded="pageLoaded"
+    class="page"
+    xmlns:FirebaseMLKitBarcodeScanning="nativescript-plugin-firebase/mlkit/barcodescanning"
+    xmlns:FirebaseMLKitFaceDetection="nativescript-plugin-firebase/mlkit/facedetection">
   <TabView.items>
 
     <TabViewItem title="ML Kit">
@@ -146,11 +150,24 @@
                 class="barcodescanner"
                 scanResult="onBarcodesScanResult" />
 
-            <!--<Label row="3" text="Barcode format:" />-->
-            <!--<Label row="3" col="1" text="{{ barcodeFormat }}" />-->
+            <!--FirebaseMLKitFaceDetection:MLKitFaceDetection
+                row="2"
+                colSpan="2"
+                class="barcodescanner"
+                scanResult="onFaceDetectionResult" /-->
+
+            <Label row="3" text="Barcode format:" />
+            <Label row="3" col="1" text="{{ barcodeFormat }}" />
+
+            <Label row="4" text="Barcode value:" />
+            <Label row="4" col="1" text="{{ barcodeValue }}" />
+
+            <!--<Label row="3" colSpan="2" text="{{ allOK }}" textWrap="true" />-->
+
+            <!--<Label row="4" text="{{ textValue }}" textWrap="true" />-->
+            <!--<Label row="4" col="1" text="If all above 70%, the image is shown here." textWrap="true" visibility="{{ lastMatch ? 'collapsed' : 'visible' }} " />-->
+            <!--<Image row="4" col="1" src="{{ lastMatch }}" visibility="{{ lastMatch ? 'visible' : 'collapsed' }} " />-->
 
-            <!--<Label row="4" text="Barcode value:" />-->
-            <Label row="3" colSpan="2" text="{{ textValue }}" textWrap="true" />
 
 
 
diff --git a/demo/app_resources/Android/src/main/AndroidManifest.xml b/demo/app_resources/Android/src/main/AndroidManifest.xml
index 8df5b08d..6d19f56e 100644
--- a/demo/app_resources/Android/src/main/AndroidManifest.xml
+++ b/demo/app_resources/Android/src/main/AndroidManifest.xml
@@ -31,7 +31,7 @@
 
 		<meta-data
 				android:name="com.google.firebase.ml.vision.DEPENDENCIES"
-				android:value="text,barcode" />
+				android:value="text,barcode,face" />
 
 		<activity
 			android:name="com.tns.NativeScriptActivity"
diff --git a/src/mlkit/barcodescanning/barcodescanning-common.ts b/src/mlkit/barcodescanning/barcodescanning-common.ts
index 79935a3f..883e2235 100644
--- a/src/mlkit/barcodescanning/barcodescanning-common.ts
+++ b/src/mlkit/barcodescanning/barcodescanning-common.ts
@@ -1,6 +1,6 @@
-import { ContentView } from "tns-core-modules/ui/content-view";
 import { booleanConverter } from "tns-core-modules/ui/core/view-base";
 import { Property } from "tns-core-modules/ui/core/properties";
+import { MLKitCameraView } from "../mlkit-cameraview";
 
 export enum BarcodeFormat {
   // UNKNOWN = -1,
@@ -20,10 +20,6 @@ export enum BarcodeFormat {
   AZTEC = 4096,
 }
 
-export function getBarcodeFormatFromIndex(index: number): string {
-  return BarcodeFormat[index];
-}
-
 export const formatsProperty = new Property<MLKitBarcodeScanner, string>({
   name: "formats",
   defaultValue: null,
@@ -47,7 +43,7 @@ export const reportDuplicatesProperty = new Property<MLKitBarcodeScanner, boolea
   valueConverter: booleanConverter
 });
 
-export abstract class MLKitBarcodeScanner extends ContentView {
+export abstract class MLKitBarcodeScanner extends MLKitCameraView {
   static scanResultEvent: string = "scanResult";
 
   protected formats: string;
diff --git a/src/mlkit/barcodescanning/index.android.ts b/src/mlkit/barcodescanning/index.android.ts
index 0858746e..585f9847 100644
--- a/src/mlkit/barcodescanning/index.android.ts
+++ b/src/mlkit/barcodescanning/index.android.ts
@@ -1,340 +1,44 @@
 import { ImageSource } from "tns-core-modules/image-source";
-import * as utils from "tns-core-modules/utils/utils";
-import * as application from "tns-core-modules/application";
 import { MLKitScanBarcodesOptions, MLKitScanBarcodesResult } from "./";
 import { MLKitOptions } from "../index";
 import { BarcodeFormat, MLKitBarcodeScanner as MLKitBarcodeScannerBase } from "./barcodescanning-common";
-import { MLKitRecognizeTextResult } from "../textrecognition";
-const CAMERA_PERMISSION_REQUEST_CODE = 502;
 
-declare const com, android: any;
+declare const com: any;
 
-class SizePair {
-  pictureSize: {
-    width: number;
-    height: number;
-  };
-  previewSize: {
-    width: number;
-    height: number;
-  };
-}
-
-// TODO pause/resume handling
-// TODO prolly need to extract common stuff to a platform-specific superclass extending MLKitBarcodeScannerBase (for permission stuff etc)
 export class MLKitBarcodeScanner extends MLKitBarcodeScannerBase {
 
-  private surfaceView: android.view.SurfaceView;
-  private bytesToByteBuffer = new Map();
-  private pendingFrameData = null;
-  private rotation;
-
-  createNativeView(): Object {
-    let v = super.createNativeView(); // TODO required even?
-    console.log("-- createNativeView");
-
-    if (this.hasCamera()) {
-      const permissionCb = (args: application.AndroidActivityRequestPermissionsEventData) => {
-        if (args.requestCode === CAMERA_PERMISSION_REQUEST_CODE) {
-          application.android.off(application.AndroidApplication.activityRequestPermissionsEvent, permissionCb);
-
-          for (let i = 0; i < args.permissions.length; i++) {
-            if (args.grantResults[i] === android.content.pm.PackageManager.PERMISSION_DENIED) {
-              console.log("Camera permission denied");
-              return;
-            }
-          }
-
-          this.initView();
-        }
-      };
-
-      // grab the permission dialog result
-      application.android.on(application.AndroidApplication.activityRequestPermissionsEvent, permissionCb);
-
-      // invoke the permission dialog
-      (android.support.v4.app.ActivityCompat as any).requestPermissions(
-          application.android.foregroundActivity || application.android.startActivity,
-          [android.Manifest.permission.CAMERA],
-          CAMERA_PERMISSION_REQUEST_CODE
-      );
-    } else {
-      console.log("There's no Camera on this device :(");
-    }
-    return v;
+  protected createDetector(): any {
+    return getBarcodeDetector();
   }
 
-  initView() {
-    if (this.preferFrontCamera) {
-      // this._reader.switchDeviceInput();
-    }
-
-    this.surfaceView = new android.view.SurfaceView(utils.ad.getApplicationContext());
-
-    this.nativeView.addView(this.surfaceView);
-
-    // TODO use callbacks instead: https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/CameraSourcePreview.java#L47
-    setTimeout(() => {
-      const surfaceHolder = this.surfaceView.getHolder();
-      const cameraFacingRequested = android.hardware.Camera.CameraInfo.CAMERA_FACING_BACK;
-      const cameraInfo = new android.hardware.Camera.CameraInfo();
-
-      let requestedCameraId = android.hardware.Camera.CameraInfo.CAMERA_FACING_BACK; // use this as the default
-      for (let i = 0; i < android.hardware.Camera.getNumberOfCameras(); ++i) {
-        android.hardware.Camera.getCameraInfo(i, cameraInfo);
-        if (cameraInfo.facing === cameraFacingRequested) {
-          requestedCameraId = i;
-          break;
-        }
-      }
-      console.log(">>> selected camera id: " + requestedCameraId);
-      const camera = android.hardware.Camera.open(requestedCameraId);
-
-      let sizePair = this.selectSizePair(camera, 640, 480); // TODO based on wrapping frame
-      console.log(">>> sizePair.pictureSize: " + sizePair.pictureSize);
-      console.log(">>> sizePair.pictureSize.xy: " + sizePair.pictureSize.width + " x " + sizePair.pictureSize.height);
-      console.log(">>> sizePair.previewSize.xy: " + sizePair.previewSize.width + " x " + sizePair.previewSize.height);
-
-      if (!sizePair) {
-        console.log("Could not find suitable preview size.");
-        return;
-      }
-
-      let pictureSize = sizePair.pictureSize;
-      let previewSize = sizePair.previewSize;
+  protected createSuccessListener(): any {
+    return new com.google.android.gms.tasks.OnSuccessListener({
+      onSuccess: (barcodes) => {
 
-      const parameters = camera.getParameters();
-      console.log(">>> parameters: " + parameters);
+        const imageSource = new ImageSource();
+        imageSource.setNativeSource(this.lastVisionImage.getBitmapForDebugging());
 
-      if (pictureSize) {
-        parameters.setPictureSize(pictureSize.width, pictureSize.height);
-      }
-      parameters.setPreviewSize(previewSize.width, previewSize.height);
-
-      parameters.setPreviewFormat(android.graphics.ImageFormat.NV21);
-
-      this.setRotation(camera, parameters, requestedCameraId);
-
-      if (parameters.getSupportedFocusModes().contains(android.hardware.Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
-        parameters.setFocusMode(android.hardware.Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
-        console.log("Camera auto focus is supported.");
-      } else {
-        console.log("Camera auto focus is not supported on this device.");
-      }
-
-      // TODO this setter seems odd, but it's part of the example: https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/CameraSource.java#L312
-      camera.setParameters(parameters);
-
-      // TODO reuse with other function
-      const firebaseVisionBarcodeDetector = getBarcodeDetector(options.formats);
-
-      const firebaseVisionTextDetector = com.google.firebase.ml.vision.FirebaseVision.getInstance().getVisionTextDetector();
-
-      const onSuccessListener = new com.google.android.gms.tasks.OnSuccessListener({
-        onSuccess: (textBlocks) => {
-          const blocks = textBlocks.getBlocks();
+        const result = <MLKitScanBarcodesResult>{
+          imageSource: imageSource,
+          barcodes: []
+        };
 
-          const result = <MLKitRecognizeTextResult>{
-            features: []
-          };
-
-          // see https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/textrecognition/TextRecognitionProcessor.java#L62
-          for (let i = 0; i < blocks.size(); i++) {
-            const textBlock = blocks.get(i);
-            result.features.push({
-              text: textBlock.getText()
-            });
-          }
-
-          this.notify({
-            eventName: MLKitBarcodeScanner.scanResultEvent,
-            object: this,
-            value: result
+        // see https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/textrecognition/TextRecognitionProcessor.java#L62
+        for (let i = 0; i < barcodes.size(); i++) {
+          const barcode = barcodes.get(i);
+          result.barcodes.push({
+            value: barcode.getRawValue(),
+            format: BarcodeFormat[barcode.getFormat()]
           });
-
-        }
-      });
-
-      const onFailureListener = new com.google.android.gms.tasks.OnFailureListener({
-        onFailure: exception => console.log(exception.getMessage())
-      });
-
-      let metadata =
-          new com.google.firebase.ml.vision.common.FirebaseVisionImageMetadata.Builder()
-              .setFormat(com.google.firebase.ml.vision.common.FirebaseVisionImageMetadata.IMAGE_FORMAT_NV21)
-              .setWidth(previewSize.width)
-              .setHeight(previewSize.height)
-              .setRotation(this.rotation)
-              .build();
-
-      camera.setPreviewCallbackWithBuffer(new android.hardware.Camera.PreviewCallback({
-        onPreviewFrame: (byteArray, camera) => {
-
-          if (this.pendingFrameData !== null) {
-            camera.addCallbackBuffer(this.pendingFrameData.array());
-            this.pendingFrameData = null;
-          }
-
-          if (!this.bytesToByteBuffer.has(byteArray)) {
-            console.log("Skipping frame");
-            return;
-          }
-
-          this.pendingFrameData = this.bytesToByteBuffer.get(byteArray);
-          let data = this.pendingFrameData;
-          // pendingFrameData = null;
-
-          // TODO (although it seems fine,) if this is too slow we need a worker to process these threads (see the async approach of https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/CameraSource.java#L669)
-          // TODO .. or we don't need the pendingFrame map bs and just skip every n frames instead of inspecting every frame
-
-          firebaseVisionTextDetector
-              .detectInImage(com.google.firebase.ml.vision.common.FirebaseVisionImage.fromByteBuffer(data, metadata))
-              .addOnSuccessListener(onSuccessListener)
-              .addOnFailureListener(onFailureListener);
-
-          // TODO when to close?
-          // firebaseVisionBarcodeDetector.close();
         }
-      }));
-
-      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
-      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
-      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
-      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
-
-      camera.setPreviewDisplay(surfaceHolder);
-      camera.startPreview();
-
-    }, 500);
-  }
-
-  private generateValidPreviewSizeList(camera): Array<SizePair> {
-    let parameters = camera.getParameters();
-    let supportedPreviewSizes = parameters.getSupportedPreviewSizes();
-    let supportedPictureSizes = parameters.getSupportedPictureSizes();
-    let validPreviewSizes: Array<SizePair> = [];
-    for (let i = 0; i < supportedPreviewSizes.size(); i++) {
-      let previewSize = supportedPreviewSizes.get(i);
-      let previewAspectRatio = previewSize.width / previewSize.height;
-
-      // By looping through the picture sizes in order, we favor the higher resolutions.
-      // We choose the highest resolution in order to support taking the full resolution
-      // picture later.
-      for (let j = 0; j < supportedPictureSizes.size(); j++) {
-        let pictureSize = supportedPictureSizes.get(j);
-        let pictureAspectRatio = pictureSize.width / pictureSize.height;
-        if (Math.abs(previewAspectRatio - pictureAspectRatio) < 0.01 /* ASPECT_RATIO_TOLERANCE */) {
-          validPreviewSizes.push({ previewSize: previewSize, pictureSize: pictureSize });
-          break;
-        }
-      }
-    }
-
-    // If there are no picture sizes with the same aspect ratio as any preview sizes, allow all
-    // of the preview sizes and hope that the camera can handle it.  Probably unlikely, but we
-    // still account for it.
-    if (validPreviewSizes.length === 0) {
-      console.log("No preview sizes have a corresponding same-aspect-ratio picture size");
-      for (let i = 0; i < supportedPreviewSizes.size(); i++) {
-        let previewSize = supportedPreviewSizes.get(i);
-        // The null picture size will let us know that we shouldn't set a picture size.
-        validPreviewSizes.push({ previewSize: previewSize, pictureSize: null });
-      }
-    }
-
-    return validPreviewSizes;
-  }
 
-  private selectSizePair(camera, desiredWidth, desiredHeight): SizePair {
-    const validPreviewSizes = this.generateValidPreviewSizeList(camera);
-
-    // The method for selecting the best size is to minimize the sum of the differences between
-    // the desired values and the actual values for width and height.  This is certainly not the
-    // only way to select the best size, but it provides a decent tradeoff between using the
-    // closest aspect ratio vs. using the closest pixel area.
-    let selectedPair = null;
-    let minDiff = java.lang.Integer.MAX_VALUE;
-    for (let i = 0; i < validPreviewSizes.length; i++) {
-      const sizePair = validPreviewSizes[i];
-      let size = sizePair.previewSize;
-      let diff = Math.abs(size.width - desiredWidth) + Math.abs(size.height - desiredHeight);
-      if (diff < minDiff) {
-        selectedPair = sizePair;
-        minDiff = diff;
+        this.notify({
+          eventName: MLKitBarcodeScanner.scanResultEvent,
+          object: this,
+          value: result
+        });
       }
-    }
-
-    return selectedPair;
-  }
-
-  private createPreviewBuffer(previewSize): any {
-    let bitsPerPixel = android.graphics.ImageFormat.getBitsPerPixel(android.graphics.ImageFormat.NV21);
-    let sizeInBits = previewSize.height * previewSize.width * bitsPerPixel;
-    let bufferSize = Math.ceil(sizeInBits / 8.0) + 1;
-    let byteArray = Array.create('byte', bufferSize);
-    let buffer = java.nio.ByteBuffer.wrap(byteArray);
-
-    if (!buffer.hasArray() || (buffer.array() !== byteArray)) {
-      console.log("Failed to create valid buffer for camera source.");
-    } else {
-      this.bytesToByteBuffer.set(byteArray, buffer);
-      return byteArray;
-    }
-  }
-
-  private setRotation(camera, parameters, cameraId): void {
-    let windowManager = (application.android.foregroundActivity || application.android.startActivity).getSystemService(android.content.Context.WINDOW_SERVICE);
-    let degrees = 0;
-    const deviceRotation = windowManager.getDefaultDisplay().getRotation();
-    switch (deviceRotation) {
-      case android.view.Surface.ROTATION_0:
-        degrees = 0;
-        break;
-      case android.view.Surface.ROTATION_90:
-        degrees = 90;
-        break;
-      case android.view.Surface.ROTATION_180:
-        degrees = 180;
-        break;
-      case android.view.Surface.ROTATION_270:
-        degrees = 270;
-        break;
-      default:
-        console.log("Bad rotation value: " + deviceRotation);
-    }
-
-    const cameraInfo = new android.hardware.Camera.CameraInfo();
-    android.hardware.Camera.getCameraInfo(cameraId, cameraInfo);
-
-    let angle;
-    let displayAngle;
-    if (cameraInfo.facing === android.hardware.Camera.CameraInfo.CAMERA_FACING_FRONT) {
-      angle = (cameraInfo.orientation + degrees) % 360;
-      displayAngle = (360 - angle) % 360; // compensate for it being mirrored
-    } else { // back-facing
-      angle = (cameraInfo.orientation - degrees + 360) % 360;
-      displayAngle = angle;
-    }
-
-    // This corresponds to the rotation constants.
-    this.rotation = angle / 90;
-
-    camera.setDisplayOrientation(displayAngle);
-    parameters.setRotation(angle);
-  }
-
-  // public onLayout(left: number, top: number, right: number, bottom: number): void {
-  //   super.onLayout(left, top, right, bottom);
-  //   if (this._hasSupport && this.ios) {
-  //     this._reader.previewLayer.frame = this.ios.layer.bounds;
-  //   }
-  // }
-
-  private hasCamera() {
-    return !!utils.ad
-        .getApplicationContext()
-        .getPackageManager()
-        .hasSystemFeature("android.hardware.camera");
+    });
   }
 }
 
diff --git a/src/mlkit/barcodescanning/index.d.ts b/src/mlkit/barcodescanning/index.d.ts
index a71067cd..066c92f0 100644
--- a/src/mlkit/barcodescanning/index.d.ts
+++ b/src/mlkit/barcodescanning/index.d.ts
@@ -1,10 +1,10 @@
 import { MLKitOptions } from "../";
-import { ContentView } from "tns-core-modules/ui/content-view";
 import { BarcodeFormat } from "./barcodescanning-common";
+import { MLKitResult, MLKitCameraView } from "../index";
 
 export declare const BarcodeFormat: typeof BarcodeFormat;
 
-export interface MLKitScanBarcodesResult {
+export interface MLKitScanBarcodesResult extends MLKitResult {
   barcodes: Array<{
     value: string;
     format: string;
@@ -21,4 +21,4 @@ export interface MLKitScanBarcodesOptions extends MLKitOptions {
 
 export declare function scanBarcodes(options: MLKitScanBarcodesOptions): Promise<MLKitScanBarcodesResult>;
 
-export declare class MLKitBarcodeScanner extends ContentView {}
+export declare class MLKitBarcodeScanner extends MLKitCameraView {}
diff --git a/src/mlkit/barcodescanning/index.ios.ts b/src/mlkit/barcodescanning/index.ios.ts
index f167dfdc..350d5a22 100644
--- a/src/mlkit/barcodescanning/index.ios.ts
+++ b/src/mlkit/barcodescanning/index.ios.ts
@@ -1,64 +1,18 @@
 import { ImageSource } from "tns-core-modules/image-source";
-import { BarcodeFormat, MLKitBarcodeScanner as MLKitBarcodeScannerBase } from "./barcodescanning-common";
+import { BarcodeFormat } from "./barcodescanning-common";
+import { MLKitCameraView as MLKitBarcodeScannerBase } from "../mlkit-cameraview";
 import { MLKitScanBarcodesOptions, MLKitScanBarcodesResult } from "./index";
 import { MLKitOptions } from "../index";
 
 export class MLKitBarcodeScanner extends MLKitBarcodeScannerBase {
 
-  // private _reader: QRCodeReader;
-  // private _scanner: QRCodeReaderViewController;
-
-  constructor() {
-    super();
-    console.log("-- constr view");
+  protected createDetector(): any {
   }
 
-  createNativeView(): Object {
-    let v = super.createNativeView();
-    console.log("-- createNativeView");
-    this.initView();
-    return v;
+  protected createFailureListener(): any {
   }
 
-  initView() {
-    // const types = getBarcodeTypes(this.formats);
-    // this._reader = QRCodeReader.readerWithMetadataObjectTypes(<any>types);
-
-    let torch = false;
-    let flip = false;
-    let closeButtonLabel = null;
-    let cancelLabelBackgroundColor = null;
-
-    if (this.preferFrontCamera) {
-      // this._reader.switchDeviceInput();
-    }
-
-    // this._scanner = QRCodeReaderViewController.readerWithCancelButtonTitleCodeReaderStartScanningAtLoadShowSwitchCameraButtonShowTorchButtonCancelButtonBackgroundColor(
-    //     closeButtonLabel, this._reader, true, flip, torch, cancelLabelBackgroundColor);
-    // this._scanner.modalPresentationStyle = UIModalPresentationStyle.CurrentContext;
-
-    /*
-    const that = this;
-    let delegate = QRCodeReaderDelegateImpl.initWithOwner(new WeakRef(this));
-    delegate.setCallback(
-        this.beepOnScan,
-        true,
-        this.reportDuplicates,
-        (text: string, format: string) => {
-          that.notify({
-            eventName: BarcodeScannerBaseView.scanResultEvent,
-            object: that,
-            format: format,
-            text: text
-          });
-        });
-    this._scanner.delegate = delegate;
-
-    if (this.ios) {
-      this.ios.layer.insertSublayerAtIndex(this._reader.previewLayer, 0);
-      this._reader.startScanning();
-    }
-    */
+  protected createSuccessListener(): any {
   }
 
   // public onLayout(left: number, top: number, right: number, bottom: number): void {
diff --git a/src/mlkit/facedetection/facedetection-common.ts b/src/mlkit/facedetection/facedetection-common.ts
new file mode 100644
index 00000000..5788762a
--- /dev/null
+++ b/src/mlkit/facedetection/facedetection-common.ts
@@ -0,0 +1,32 @@
+import { booleanConverter } from "tns-core-modules/ui/core/view-base";
+import { Property } from "tns-core-modules/ui/core/properties";
+import { MLKitCameraView } from "../mlkit-cameraview";
+
+export const formatsProperty = new Property<MLKitFaceDetection, string>({
+  name: "formats",
+  defaultValue: null,
+});
+
+export const preferFrontCameraProperty = new Property<MLKitFaceDetection, boolean>({
+  name: "preferFrontCamera",
+  defaultValue: false,
+  valueConverter: booleanConverter
+});
+
+export abstract class MLKitFaceDetection extends MLKitCameraView {
+  static scanResultEvent: string = "scanResult";
+
+  protected formats: string;
+  protected preferFrontCamera: boolean;
+
+  [formatsProperty.setNative](value: string) {
+    this.formats = value;
+  }
+
+  [preferFrontCameraProperty.setNative](value: boolean) {
+    this.preferFrontCamera = value;
+  }
+}
+
+formatsProperty.register(MLKitFaceDetection);
+preferFrontCameraProperty.register(MLKitFaceDetection);
diff --git a/src/mlkit/facedetection/index.android.ts b/src/mlkit/facedetection/index.android.ts
new file mode 100644
index 00000000..e9c0e13d
--- /dev/null
+++ b/src/mlkit/facedetection/index.android.ts
@@ -0,0 +1,106 @@
+import { ImageSource } from "tns-core-modules/image-source";
+import { MLKitDetectFacesOptions, MLKitDetectFacesResult } from "./";
+import { MLKitOptions } from "../index";
+import { MLKitFaceDetection as MLKitFaceDetectionBase } from "./facedetection-common";
+
+declare const com: any;
+
+export class MLKitFaceDetection extends MLKitFaceDetectionBase {
+
+  protected createDetector(): any {
+    return getFaceDetector();
+  }
+
+  protected createSuccessListener(): any {
+    return new com.google.android.gms.tasks.OnSuccessListener({
+      onSuccess: (faces) => {
+
+        const imageSource = new ImageSource();
+        imageSource.setNativeSource(this.lastVisionImage.getBitmapForDebugging());
+
+        const result = <MLKitDetectFacesResult>{
+          imageSource: imageSource,
+          faces: []
+        };
+
+        // see https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/textrecognition/TextRecognitionProcessor.java#L62
+        for (let i = 0; i < faces.size(); i++) {
+          const face = faces.get(i);
+          result.faces.push({
+            smilingProbability: face.getSmilingProbability() !== com.google.firebase.ml.vision.face.FirebaseVisionFace.UNCOMPUTED_PROBABILITY ? face.getSmilingProbability() : undefined,
+            leftEyeOpenProbability: face.getLeftEyeOpenProbability() !== com.google.firebase.ml.vision.face.FirebaseVisionFace.UNCOMPUTED_PROBABILITY ? face.getLeftEyeOpenProbability() : undefined,
+            rightEyeOpenProbability: face.getRightEyeOpenProbability() !== com.google.firebase.ml.vision.face.FirebaseVisionFace.UNCOMPUTED_PROBABILITY ? face.getRightEyeOpenProbability() : undefined
+          });
+        }
+
+        this.notify({
+          eventName: MLKitFaceDetection.scanResultEvent,
+          object: this,
+          value: result
+        });
+      }
+    });
+  }
+}
+
+function getFaceDetector(): any {
+  const faceDetectorOptions =
+      new com.google.firebase.ml.vision.face.FirebaseVisionFaceDetectorOptions.Builder()
+          .setModeType(com.google.firebase.ml.vision.face.FirebaseVisionFaceDetectorOptions.ACCURATE_MODE)
+          .setLandmarkType(com.google.firebase.ml.vision.face.FirebaseVisionFaceDetectorOptions.ALL_LANDMARKS)
+          .setClassificationType(com.google.firebase.ml.vision.face.FirebaseVisionFaceDetectorOptions.ALL_CLASSIFICATIONS)
+          .setMinFaceSize(0.15)
+          .setTrackingEnabled(false)
+          .build();
+
+  return com.google.firebase.ml.vision.FirebaseVision.getInstance().getVisionFaceDetector(faceDetectorOptions);
+}
+
+export function detectFaces(options: MLKitDetectFacesOptions): Promise<MLKitDetectFacesResult> {
+  return new Promise((resolve, reject) => {
+    try {
+      const firebaseVisionFaceDetector = getFaceDetector();
+
+      const onSuccessListener = new com.google.android.gms.tasks.OnSuccessListener({
+        onSuccess: (faces) => {
+
+          const result = <MLKitDetectFacesResult>{
+            faces: []
+          };
+
+          // see https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/textrecognition/TextRecognitionProcessor.java#L62
+          for (let i = 0; i < faces.size(); i++) {
+            const face = faces.get(i);
+            result.faces.push({
+              smilingProbability: face.getSmilingProbability() !== com.google.firebase.ml.vision.face.FirebaseVisionFace.UNCOMPUTED_PROBABILITY ? face.getSmilingProbability() : undefined,
+              leftEyeOpenProbability: face.getLeftEyeOpenProbability() !== com.google.firebase.ml.vision.face.FirebaseVisionFace.UNCOMPUTED_PROBABILITY ? face.getLeftEyeOpenProbability() : undefined,
+              rightEyeOpenProbability: face.getRightEyeOpenProbability() !== com.google.firebase.ml.vision.face.FirebaseVisionFace.UNCOMPUTED_PROBABILITY ? face.getRightEyeOpenProbability() : undefined
+            });
+          }
+
+          resolve(result);
+          firebaseVisionFaceDetector.close();
+        }
+      });
+
+      const onFailureListener = new com.google.android.gms.tasks.OnFailureListener({
+        onFailure: exception => reject(exception.getMessage())
+      });
+
+      firebaseVisionFaceDetector
+          .detectInImage(getImage(options))
+          .addOnSuccessListener(onSuccessListener)
+          .addOnFailureListener(onFailureListener);
+
+    } catch (ex) {
+      console.log("Error in firebase.mlkit.detectFaces: " + ex);
+      reject(ex);
+    }
+  });
+}
+
+// TODO move up
+function getImage(options: MLKitOptions): any /* com.google.firebase.ml.vision.common.FirebaseVisionImage */ {
+  const image: android.graphics.Bitmap = options.image instanceof ImageSource ? options.image.android : options.image.imageSource.android;
+  return com.google.firebase.ml.vision.common.FirebaseVisionImage.fromBitmap(image);
+}
diff --git a/src/mlkit/facedetection/index.d.ts b/src/mlkit/facedetection/index.d.ts
new file mode 100644
index 00000000..350282f7
--- /dev/null
+++ b/src/mlkit/facedetection/index.d.ts
@@ -0,0 +1,20 @@
+import { MLKitOptions } from "../";
+import { BarcodeFormat } from "./barcodescanning-common";
+import { MLKitCameraView, MLKitResult } from "../index";
+
+export interface MLKitDetectFacesResult extends MLKitResult {
+  // TODO there are more properties we can return, see https://firebase.google.com/docs/ml-kit/android/detect-faces
+  faces: Array<{
+    smilingProbability: number;
+    leftEyeOpenProbability: number;
+    rightEyeOpenProbability: number;
+  }>;
+}
+
+export interface MLKitDetectFacesOptions extends MLKitOptions {
+  // TODO there are a few options here
+}
+
+export declare function detectFaces(options: MLKitDetectFacesOptions): Promise<MLKitDetectFacesResult>;
+
+export declare class MLKitFaceDetection extends MLKitCameraView {}
diff --git a/src/mlkit/index.ts b/src/mlkit/index.ts
index b2657267..016e15a5 100644
--- a/src/mlkit/index.ts
+++ b/src/mlkit/index.ts
@@ -1,5 +1,6 @@
 import * as textrecognition from "./textrecognition";
 import * as barcodescanning from "./barcodescanning";
+import * as facedetection from "./facedetection";
 import { ImageSource } from "tns-core-modules/image-source";
 import { Image } from "tns-core-modules/ui/image";
 
@@ -11,8 +12,20 @@ export interface MLKitMultiEngineOptions extends MLKitOptions {
   engine?: "device" | "cloud"; // defaults to local, as cloud requires an additional plan
 }
 
+export interface MLKitResult {
+  /**
+   * Only set when using a camera stream,
+   * because when detecting from static images... you already have the image, right? :)
+   */
+  imageSource?: ImageSource;
+}
+
+export declare class MLKitBarcodeScanner {
+}
+
 export {
   textrecognition,
-  barcodescanning
+  barcodescanning,
+  facedetection
 };
 
diff --git a/src/mlkit/mlkit-cameraview.android.ts b/src/mlkit/mlkit-cameraview.android.ts
new file mode 100644
index 00000000..cf9e7cb1
--- /dev/null
+++ b/src/mlkit/mlkit-cameraview.android.ts
@@ -0,0 +1,312 @@
+import { ContentView } from "tns-core-modules/ui/content-view";
+import * as application from "tns-core-modules/application";
+import * as utils from "tns-core-modules/utils/utils";
+
+const CAMERA_PERMISSION_REQUEST_CODE = 502;
+
+declare const com, android: any;
+
+class SizePair {
+  pictureSize: {
+    width: number;
+    height: number;
+  };
+  previewSize: {
+    width: number;
+    height: number;
+  };
+}
+
+// TODO pause/resume handling
+export abstract class MLKitCameraView extends ContentView {
+  private surfaceView: android.view.SurfaceView;
+  private bytesToByteBuffer = new Map();
+  private pendingFrameData = null;
+  protected rotation;
+  protected lastVisionImage;
+
+  createNativeView(): Object {
+    let v = super.createNativeView(); // TODO required even?
+    console.log("-- createNativeView");
+
+    if (this.hasCamera()) {
+      const permissionCb = (args: application.AndroidActivityRequestPermissionsEventData) => {
+        if (args.requestCode === CAMERA_PERMISSION_REQUEST_CODE) {
+          application.android.off(application.AndroidApplication.activityRequestPermissionsEvent, permissionCb);
+
+          for (let i = 0; i < args.permissions.length; i++) {
+            if (args.grantResults[i] === android.content.pm.PackageManager.PERMISSION_DENIED) {
+              console.log("Camera permission denied");
+              return;
+            }
+          }
+
+          this.initView();
+        }
+      };
+
+      // grab the permission dialog result
+      application.android.on(application.AndroidApplication.activityRequestPermissionsEvent, permissionCb);
+
+      // invoke the permission dialog
+      (android.support.v4.app.ActivityCompat as any).requestPermissions(
+          application.android.foregroundActivity || application.android.startActivity,
+          [android.Manifest.permission.CAMERA],
+          CAMERA_PERMISSION_REQUEST_CODE
+      );
+    } else {
+      console.log("There's no Camera on this device :(");
+    }
+    return v;
+  }
+
+  private hasCamera() {
+    return !!utils.ad
+        .getApplicationContext()
+        .getPackageManager()
+        .hasSystemFeature("android.hardware.camera");
+  }
+
+  private initView() {
+    // if (this.preferFrontCamera) {
+    // this._reader.switchDeviceInput();
+    // }
+
+    this.surfaceView = new android.view.SurfaceView(utils.ad.getApplicationContext());
+    this.nativeView.addView(this.surfaceView);
+
+    // TODO use callbacks instead: https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/CameraSourcePreview.java#L47
+    setTimeout(() => {
+      const surfaceHolder = this.surfaceView.getHolder();
+      const cameraFacingRequested = android.hardware.Camera.CameraInfo.CAMERA_FACING_BACK;
+      const cameraInfo = new android.hardware.Camera.CameraInfo();
+
+      let requestedCameraId = android.hardware.Camera.CameraInfo.CAMERA_FACING_BACK; // use this as the default
+      for (let i = 0; i < android.hardware.Camera.getNumberOfCameras(); ++i) {
+        android.hardware.Camera.getCameraInfo(i, cameraInfo);
+        if (cameraInfo.facing === cameraFacingRequested) {
+          requestedCameraId = i;
+          break;
+        }
+      }
+      console.log(">>> selected camera id: " + requestedCameraId);
+      const camera = android.hardware.Camera.open(requestedCameraId);
+
+      const sizePair = this.selectSizePair(camera, 640, 480); // TODO based on wrapping frame
+      console.log(">>> sizePair.pictureSize: " + sizePair.pictureSize);
+      console.log(">>> sizePair.pictureSize.xy: " + sizePair.pictureSize.width + " x " + sizePair.pictureSize.height);
+      console.log(">>> sizePair.previewSize.xy: " + sizePair.previewSize.width + " x " + sizePair.previewSize.height);
+
+      if (!sizePair) {
+        console.log("Could not find suitable preview size.");
+        return;
+      }
+
+      let pictureSize = sizePair.pictureSize;
+      let previewSize = sizePair.previewSize;
+
+      const parameters = camera.getParameters();
+      console.log(">>> parameters: " + parameters);
+
+      if (pictureSize) {
+        parameters.setPictureSize(pictureSize.width, pictureSize.height);
+      }
+
+      parameters.setPreviewSize(previewSize.width, previewSize.height);
+
+      parameters.setPreviewFormat(android.graphics.ImageFormat.NV21);
+
+      this.setRotation(camera, parameters, requestedCameraId);
+
+      if (parameters.getSupportedFocusModes().contains(android.hardware.Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
+        parameters.setFocusMode(android.hardware.Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
+        console.log("Camera auto focus is supported.");
+      } else {
+        console.log("Camera auto focus is not supported on this device.");
+      }
+
+      // TODO this setter seems odd, but it's part of the example: https://github.com/firebase/quickstart-android/blob/0f4c86877fc5f771cac95797dffa8bd026dd9dc7/mlkit/app/src/main/java/com/google/firebase/samples/apps/mlkit/CameraSource.java#L312
+      camera.setParameters(parameters);
+
+      const detector = this.createDetector();
+      const onSuccessListener = this.createSuccessListener();
+      const onFailureListener = this.createFailureListener();
+
+      let metadata =
+          new com.google.firebase.ml.vision.common.FirebaseVisionImageMetadata.Builder()
+              .setFormat(com.google.firebase.ml.vision.common.FirebaseVisionImageMetadata.IMAGE_FORMAT_NV21)
+              .setWidth(previewSize.width)
+              .setHeight(previewSize.height)
+              .setRotation(this.rotation)
+              .build();
+
+      let throttle = 0;
+      camera.setPreviewCallbackWithBuffer(new android.hardware.Camera.PreviewCallback({
+        onPreviewFrame: (byteArray, camera) => {
+
+          if (this.pendingFrameData !== null) {
+            camera.addCallbackBuffer(this.pendingFrameData.array());
+            this.pendingFrameData = null;
+          }
+
+          if (!this.bytesToByteBuffer.has(byteArray)) {
+            console.log("Skipping frame");
+            return;
+          }
+
+          this.pendingFrameData = this.bytesToByteBuffer.get(byteArray);
+
+          // TODO this value can be controlled from options; the higher the interval the easier it is for the device.. default 1 for full speed?
+          if (throttle++ % 5 !== 0) {
+            return;
+          }
+
+          let data = this.pendingFrameData;
+          // pendingFrameData = null;
+
+          this.lastVisionImage = com.google.firebase.ml.vision.common.FirebaseVisionImage.fromByteBuffer(data, metadata);
+
+          detector
+              .detectInImage(this.lastVisionImage)
+              .addOnSuccessListener(onSuccessListener)
+              .addOnFailureListener(onFailureListener);
+        }
+      }));
+
+      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
+      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
+      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
+      camera.addCallbackBuffer(this.createPreviewBuffer(previewSize));
+
+      camera.setPreviewDisplay(surfaceHolder);
+      camera.startPreview();
+
+    }, 500);
+  }
+
+  protected abstract createDetector(): any;
+
+  protected abstract createSuccessListener(): any;
+
+  private createFailureListener(): any {
+    return new com.google.android.gms.tasks.OnFailureListener({
+      onFailure: exception => console.log(exception.getMessage())
+    });
+  };
+
+  private generateValidPreviewSizeList(camera): Array<SizePair> {
+    let parameters = camera.getParameters();
+    let supportedPreviewSizes = parameters.getSupportedPreviewSizes();
+    let supportedPictureSizes = parameters.getSupportedPictureSizes();
+    let validPreviewSizes: Array<SizePair> = [];
+    for (let i = 0; i < supportedPreviewSizes.size(); i++) {
+      let previewSize = supportedPreviewSizes.get(i);
+      let previewAspectRatio = previewSize.width / previewSize.height;
+
+      // By looping through the picture sizes in order, we favor the higher resolutions.
+      // We choose the highest resolution in order to support taking the full resolution
+      // picture later.
+      for (let j = 0; j < supportedPictureSizes.size(); j++) {
+        let pictureSize = supportedPictureSizes.get(j);
+        let pictureAspectRatio = pictureSize.width / pictureSize.height;
+        if (Math.abs(previewAspectRatio - pictureAspectRatio) < 0.01 /* ASPECT_RATIO_TOLERANCE */) {
+          validPreviewSizes.push({previewSize: previewSize, pictureSize: pictureSize});
+          break;
+        }
+      }
+    }
+
+    // If there are no picture sizes with the same aspect ratio as any preview sizes, allow all
+    // of the preview sizes and hope that the camera can handle it.  Probably unlikely, but we
+    // still account for it.
+    if (validPreviewSizes.length === 0) {
+      console.log("No preview sizes have a corresponding same-aspect-ratio picture size");
+      for (let i = 0; i < supportedPreviewSizes.size(); i++) {
+        let previewSize = supportedPreviewSizes.get(i);
+        // The null picture size will let us know that we shouldn't set a picture size.
+        validPreviewSizes.push({previewSize: previewSize, pictureSize: null});
+      }
+    }
+
+    return validPreviewSizes;
+  }
+
+  private selectSizePair(camera, desiredWidth, desiredHeight): SizePair {
+    const validPreviewSizes = this.generateValidPreviewSizeList(camera);
+
+    // The method for selecting the best size is to minimize the sum of the differences between
+    // the desired values and the actual values for width and height.  This is certainly not the
+    // only way to select the best size, but it provides a decent tradeoff between using the
+    // closest aspect ratio vs. using the closest pixel area.
+    let selectedPair = null;
+    let minDiff = java.lang.Integer.MAX_VALUE;
+    for (let i = 0; i < validPreviewSizes.length; i++) {
+      const sizePair = validPreviewSizes[i];
+      let size = sizePair.previewSize;
+      let diff = Math.abs(size.width - desiredWidth) + Math.abs(size.height - desiredHeight);
+      if (diff < minDiff) {
+        selectedPair = sizePair;
+        minDiff = diff;
+      }
+    }
+
+    return selectedPair;
+  }
+
+  private createPreviewBuffer(previewSize): any {
+    let bitsPerPixel = android.graphics.ImageFormat.getBitsPerPixel(android.graphics.ImageFormat.NV21);
+    let sizeInBits = previewSize.height * previewSize.width * bitsPerPixel;
+    let bufferSize = Math.ceil(sizeInBits / 8.0) + 1;
+    let byteArray = Array.create('byte', bufferSize);
+    let buffer = java.nio.ByteBuffer.wrap(byteArray);
+
+    if (!buffer.hasArray() || (buffer.array() !== byteArray)) {
+      console.log("Failed to create valid buffer for camera source.");
+    } else {
+      this.bytesToByteBuffer.set(byteArray, buffer);
+      return byteArray;
+    }
+  }
+
+  private setRotation(camera, parameters, cameraId): void {
+    let windowManager = (application.android.foregroundActivity || application.android.startActivity).getSystemService(android.content.Context.WINDOW_SERVICE);
+    let degrees = 0;
+    const deviceRotation = windowManager.getDefaultDisplay().getRotation();
+    switch (deviceRotation) {
+      case android.view.Surface.ROTATION_0:
+        degrees = 0;
+        break;
+      case android.view.Surface.ROTATION_90:
+        degrees = 90;
+        break;
+      case android.view.Surface.ROTATION_180:
+        degrees = 180;
+        break;
+      case android.view.Surface.ROTATION_270:
+        degrees = 270;
+        break;
+      default:
+        console.log("Bad rotation value: " + deviceRotation);
+    }
+
+    const cameraInfo = new android.hardware.Camera.CameraInfo();
+    android.hardware.Camera.getCameraInfo(cameraId, cameraInfo);
+
+    let angle;
+    let displayAngle;
+    if (cameraInfo.facing === android.hardware.Camera.CameraInfo.CAMERA_FACING_FRONT) {
+      angle = (cameraInfo.orientation + degrees) % 360;
+      displayAngle = (360 - angle) % 360; // compensate for it being mirrored
+    } else { // back-facing
+      angle = (cameraInfo.orientation - degrees + 360) % 360;
+      displayAngle = angle;
+    }
+
+    // This corresponds to the rotation constants.
+    this.rotation = angle / 90;
+
+    camera.setDisplayOrientation(displayAngle);
+    parameters.setRotation(angle);
+  }
+
+}
diff --git a/src/mlkit/mlkit-cameraview.ios.ts b/src/mlkit/mlkit-cameraview.ios.ts
new file mode 100644
index 00000000..e69de29b
diff --git a/src/mlkit/textrecognition/index.d.ts b/src/mlkit/textrecognition/index.d.ts
index bfce7b5c..0c3661fe 100644
--- a/src/mlkit/textrecognition/index.d.ts
+++ b/src/mlkit/textrecognition/index.d.ts
@@ -1,6 +1,7 @@
 import { MLKitMultiEngineOptions } from "../";
+import { MLKitResult } from "../index";
 
-export interface MLKitRecognizeTextResult {
+export interface MLKitRecognizeTextResult extends MLKitResult {
   features: Array<{
     text: string;
   }>;