Shape Detection: Add Text Detection in Chrome Android

chrome/android/java/src/org/chromium/chrome/browser/shapedetection/TextDetectionImpl.java

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.shapedetection;
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.Rect;
+import android.util.SparseArray;
+
+import com.google.android.gms.vision.Frame;
+import com.google.android.gms.vision.text.TextBlock;
+import com.google.android.gms.vision.text.TextRecognizer;
+
+import org.chromium.base.Log;
+import org.chromium.blink.mojom.TextDetection;
+import org.chromium.blink.mojom.TextDetectionResult;
+import org.chromium.chrome.browser.externalauth.ExternalAuthUtils;
+import org.chromium.chrome.browser.externalauth.UserRecoverableErrorHandler;
+import org.chromium.gfx.mojom.RectF;
+import org.chromium.mojo.system.MojoException;
+import org.chromium.mojo.system.SharedBufferHandle;
+import org.chromium.mojo.system.SharedBufferHandle.MapFlags;
+
+import java.nio.ByteBuffer;
+
+/**
+ * Implementation of mojo TextDetection, using Google Play Services vision package.
+ */
+public class TextDetectionImpl implements TextDetection {
+    private static final String TAG = "TextDetectionImpl";
+
+    private final Context mContext;
+    private TextRecognizer mTextRecognizer;
+
+    public TextDetectionImpl(Context context) {
+        mContext = context;
+        mTextRecognizer = new TextRecognizer.Builder(mContext).build();
+    }
+
+    @Override
+    public void detect(
+            SharedBufferHandle frameData, int width, int height, DetectResponse callback) {
+        if (!ExternalAuthUtils.getInstance().canUseGooglePlayServices(
+                    mContext, new UserRecoverableErrorHandler.Silent())) {
+            Log.e(TAG, "Google Play Services not available");
+            callback.call(new TextDetectionResult[0]);
+            return;
+        }
+        // The vision library will be downloaded the first time the API is used
+        // on the device; this happens "fast", but it might have not completed,
+        // bail in this case. Also, the API was disabled between and v.9.0 and
+        // v.9.2, see https://developers.google.com/android/guides/releases.
+        if (!mTextRecognizer.isOperational()) {
+            Log.e(TAG, "TextDetector is not operational");
+            callback.call(new TextDetectionResult[0]);
+            return;
+        }
+
+        final long numPixels = (long) width * height;
+        // TODO(xianglu): https://crbug.com/670028 homogeneize overflow checking.
+        if (!frameData.isValid() || width <= 0 || height <= 0 || numPixels > (Long.MAX_VALUE / 4)) {
+            callback.call(new TextDetectionResult[0]);
+            return;
+        }
+
+        // Mapping |frameData| will fail if the intended mapped size is larger
+        // than its actual capacity, which is limited by the appropriate
+        // mojo::edk::Configuration entry.
+        ByteBuffer imageBuffer = frameData.map(0, numPixels * 4, MapFlags.none());
+        if (imageBuffer.capacity() <= 0) {
+            callback.call(new TextDetectionResult[0]);
+            return;
+        }
+
+        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        bitmap.copyPixelsFromBuffer(imageBuffer);
+
+        Frame frame = null;
+        try {
+            // This constructor implies a pixel format conversion to YUV.
+            frame = new Frame.Builder().setBitmap(bitmap).build();
+        } catch (IllegalArgumentException | IllegalStateException ex) {
+            Log.e(TAG, "Frame.Builder().setBitmap() or build(): " + ex);
+            callback.call(new TextDetectionResult[0]);
+            return;
+        }
+
+        final SparseArray<TextBlock> textBlocks = mTextRecognizer.detect(frame);
+
+        TextDetectionResult[] detectedTextArray = new TextDetectionResult[textBlocks.size()];
+        for (int i = 0; i < textBlocks.size(); i++) {
+            detectedTextArray[i] = new TextDetectionResult();
+            detectedTextArray[i].rawValue = textBlocks.valueAt(i).getValue();
+            final Rect rect = textBlocks.valueAt(i).getBoundingBox();
+            detectedTextArray[i].boundingBox = new RectF();
+            detectedTextArray[i].boundingBox.x = rect.left;
+            detectedTextArray[i].boundingBox.y = rect.top;
+            detectedTextArray[i].boundingBox.width = rect.width();
+            detectedTextArray[i].boundingBox.height = rect.height();
+        }
+        callback.call(detectedTextArray);
+    }
+
+    @Override
+    public void close() {
+        mTextRecognizer.release();
+    }
+
+    @Override
+    public void onConnectionError(MojoException e) {
+        close();
+    }
+}