Java tutorial
/* * Copyright (C) The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.google.android.gms.samples.vision.barcodereader; import android.Manifest; import android.annotation.SuppressLint; import android.app.Dialog; import android.content.Intent; import android.content.IntentFilter; import android.content.pm.PackageManager; import android.hardware.Camera; import android.os.Build; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v4.app.ActivityCompat; import android.util.Log; import android.view.GestureDetector; import android.view.LayoutInflater; import android.view.MotionEvent; import android.view.ScaleGestureDetector; import android.view.View; import android.view.ViewGroup; import android.widget.Toast; import com.google.android.gms.common.ConnectionResult; import com.google.android.gms.common.GoogleApiAvailability; import com.google.android.gms.samples.vision.barcodereader.ui.camera.CameraSource; import com.google.android.gms.samples.vision.barcodereader.ui.camera.CameraSourcePreview; import com.google.android.gms.samples.vision.barcodereader.ui.camera.GraphicOverlay; import com.google.android.gms.vision.MultiProcessor; import com.google.android.gms.vision.barcode.Barcode; import com.google.android.gms.vision.barcode.BarcodeDetector; import com.tbruyelle.rxpermissions2.RxPermissions; import java.io.IOException; import java.util.ArrayList; import io.reactivex.functions.Consumer; import xyz.belvi.mobilevisionbarcodescanner.BarcodeFragment; //import xyz.belvi.mobilevisionbarcodescanner.R; import xyz.blacktag.mobilevisionbarcodescanner.R; /** * Activity for the multi-tracker app. This app detects barcodes and displays the value with the * rear facing camera. During detection overlay graphics are drawn to indicate the position, * size, and ID of each barcode. */ public final class BarcodeCapture extends BarcodeFragment { private static final String TAG = "Barcode-reader"; // intent request code to handle updating play services if needed. private static final int RC_HANDLE_GMS = 9001; // permission request codes need to be < 256 private static final int RC_HANDLE_CAMERA_PERM = 2; public static final String BarcodeObject = "Barcode"; private CameraSource mCameraSource; private CameraSourcePreview mPreview; private GraphicOverlay<BarcodeGraphic> mGraphicOverlay; // helper objects for detecting taps and pinches. private ScaleGestureDetector scaleGestureDetector; private GestureDetector gestureDetector; /** * Initializes the UI and creates the detector pipeline. */ @Nullable @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.barcode_capture, container, false); mPreview = (CameraSourcePreview) rootView.findViewById(R.id.preview); mGraphicOverlay = (GraphicOverlay<BarcodeGraphic>) rootView.findViewById(R.id.graphicOverlay); mGraphicOverlay.setShowText(isShouldShowText()); mGraphicOverlay.setRectColors(getRectColors()); mGraphicOverlay.setDrawRect(isShowDrawRect()); // read parameters from the intent used to launch the activity. requestCameraPermission(); gestureDetector = new GestureDetector(getContext(), new CaptureGestureListener()); scaleGestureDetector = new ScaleGestureDetector(getContext(), new ScaleListener()); rootView.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(View view, MotionEvent e) { boolean b = scaleGestureDetector.onTouchEvent(e); boolean c = gestureDetector.onTouchEvent(e); return b || c || view.onTouchEvent(e); } }); return rootView; } /** * Handles the requesting of the camera permission. This includes * showing a "Snackbar" message of why the permission is needed then * sending the request. */ private void requestCameraPermission() { RxPermissions rxPermissions = new RxPermissions(getActivity()); rxPermissions.request(Manifest.permission.CAMERA).subscribe(new Consumer<Boolean>() { @Override public void accept(Boolean granted) throws Exception { if (granted) { createCameraSource(isAutoFocus(), isShowFlash()); } } }); } /** * Creates and starts the camera. Note that this uses a higher resolution in comparison * to other detection examples to enable the barcode detector to detect small barcodes * at long distances. * <p> * Suppressing InlinedApi since there is a check that the minimum version is met before using * the constant. */ @SuppressLint("InlinedApi") private void createCameraSource(boolean autoFocus, boolean useFlash) { // A barcode detector is created to track barcodes. An associated multi-processor instance // is set to receive the barcode detection results, track the barcodes, and maintain // graphics for each barcode on screen. The factory is used by the multi-processor to // create a separate tracker instance for each barcode. BarcodeDetector barcodeDetector = new BarcodeDetector.Builder(getContext()) .setBarcodeFormats(getBarcodeFormat()).build(); BarcodeTrackerFactory barcodeFactory = new BarcodeTrackerFactory(mGraphicOverlay) { @Override void onCodeDetected(Barcode barcode) { if (!isTouchAsCallback() && !supportMultipleScan()) { barcodeRetriever.onRetrieved(barcode); } } }; barcodeDetector.setProcessor(new MultiProcessor.Builder<>(barcodeFactory).build()); if (!barcodeDetector.isOperational()) { // Note: The first time that an app using the barcode or face API is installed on a // device, GMS will download a native libraries to the device in order to do detection. // Usually this completes before the app is run for the first time. But if that // download has not yet completed, then the above call will not detect any barcodes // and/or faces. // // isOperational() can be used to check if the required native libraries are currently // available. The detectors will automatically become operational once the library // downloads complete on device. Log.w(TAG, "Detector dependencies are not yet available."); // Check for low storage. If there is low storage, the native library will not be // downloaded, so detection will not become operational. IntentFilter lowstorageFilter = new IntentFilter(Intent.ACTION_DEVICE_STORAGE_LOW); boolean hasLowStorage = getActivity().registerReceiver(null, lowstorageFilter) != null; if (hasLowStorage) { Toast.makeText(getContext(), R.string.low_storage_error, Toast.LENGTH_LONG).show(); Log.w(TAG, getString(R.string.low_storage_error)); } } // Creates and starts the camera. Note that this uses a higher resolution in comparison // to other detection examples to enable the barcode detector to detect small barcodes // at long distances. CameraSource.Builder builder = new CameraSource.Builder(getContext(), barcodeDetector) .setFacing(CameraSource.CAMERA_FACING_BACK).setRequestedPreviewSize(1600, 1024) .setRequestedFps(15.0f); // make sure that auto focus is an available option if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) { builder = builder.setFocusMode(autoFocus ? Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE : null); } mCameraSource = builder.setFlashMode(useFlash ? Camera.Parameters.FLASH_MODE_TORCH : null).build(); } /** * Restarts the camera. */ @Override public void onResume() { super.onResume(); startCameraSource(); } public void refresh() { mGraphicOverlay.setDrawRect(isShowDrawRect()); mGraphicOverlay.setRectColors(getRectColors()); mGraphicOverlay.setShowText(isShouldShowText()); mCameraSource.setFocusMode(isAutoFocus() ? Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE : null); mCameraSource.setFlashMode( isShowFlash() ? Camera.Parameters.FLASH_MODE_TORCH : Camera.Parameters.FLASH_MODE_OFF); } /** * Stops the camera. */ @Override public void onPause() { super.onPause(); if (mPreview != null) { mPreview.stop(); } } /** * Releases the resources associated with the camera source, the associated detectors, and the * rest of the processing pipeline. */ @Override public void onDestroy() { super.onDestroy(); if (mPreview != null) { mPreview.release(); } } /** * Callback for the result from requesting permissions. This method * is invoked for every call on {@link #requestPermissions(String[], int)}. * <p> * <strong>Note:</strong> It is possible that the permissions request interaction * with the user is interrupted. In this case you will receive empty permissions * and results arrays which should be treated as a cancellationt * </p> * * @param requestCode The request code passed in {@link #requestPermissions(String[], int)}. * @param permissions The requested permissions. Never null. * @param grantResults The grant results for the corresponding permissions * which is either {@link PackageManager#PERMISSION_GRANTED} * or {@link PackageManager#PERMISSION_DENIED}. Never null. * @see #requestPermissions(String[], int) */ @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { if (requestCode != RC_HANDLE_CAMERA_PERM) { Log.d(TAG, "Got unexpected permission result: " + requestCode); super.onRequestPermissionsResult(requestCode, permissions, grantResults); return; } if (grantResults.length != 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { Log.d(TAG, "Camera permission granted - initialize the camera source"); // we have permission, so create the camerasource createCameraSource(isAutoFocus(), isShowFlash()); return; } barcodeRetriever.onRetrievedFailed(getString(R.string.no_camera_permission)); } /** * Starts or restarts the camera source, if it exists. If the camera source doesn't exist yet * (e.g., because onResume was called before the camera source was created), this will be called * again when the camera source is created. */ private void startCameraSource() throws SecurityException { // check that the device has play services available. int code = GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(getContext()); if (code != ConnectionResult.SUCCESS) { Dialog dlg = GoogleApiAvailability.getInstance().getErrorDialog(getActivity(), code, RC_HANDLE_GMS); dlg.show(); } if (mCameraSource != null) { try { mPreview.start(mCameraSource, mGraphicOverlay); } catch (IOException e) { Log.e(TAG, "Unable to start camera source.", e); mCameraSource.release(); mCameraSource = null; } } } /** * onTap returns the tapped barcode result to the calling Activity. * * @param rawX - the raw position of the tap * @param rawY - the raw position of the tap. * @return true if the activity is ending. */ private boolean onTap(float rawX, float rawY) { // Find tap point in preview frame coordinates. int[] location = new int[2]; mGraphicOverlay.getLocationOnScreen(location); float x = (rawX - location[0]) / mGraphicOverlay.getWidthScaleFactor(); float y = (rawY - location[1]) / mGraphicOverlay.getHeightScaleFactor(); // Find the barcode whose center is closest to the tapped point. Barcode best = null; float bestDistance = Float.MAX_VALUE; ArrayList<Barcode> allRetrieved = new ArrayList<>(); for (BarcodeGraphic graphic : mGraphicOverlay.getGraphics()) { Barcode barcode = graphic.getBarcode(); allRetrieved.add(barcode); if (barcode.getBoundingBox().contains((int) x, (int) y)) { // Exact hit, no need to keep looking. best = barcode; break; } float dx = x - barcode.getBoundingBox().centerX(); float dy = y - barcode.getBoundingBox().centerY(); float distance = (dx * dx) + (dy * dy); // actually squared distance if (distance < bestDistance) { best = barcode; bestDistance = distance; } } if (best != null) { if (barcodeRetriever != null) if (supportMultipleScan()) { barcodeRetriever.onRetrievedMultiple(best, mGraphicOverlay.getGraphics()); } else { barcodeRetriever.onRetrieved(best); } return true; } return false; } private class CaptureGestureListener extends GestureDetector.SimpleOnGestureListener { @Override public boolean onSingleTapConfirmed(MotionEvent e) { return onTap(e.getRawX(), e.getRawY()) || super.onSingleTapConfirmed(e); } } private class ScaleListener implements ScaleGestureDetector.OnScaleGestureListener { /** * Responds to scaling events for a gesture in progress. * Reported by pointer motion. * * @param detector The detector reporting the event - use this to * retrieve extended info about event state. * @return Whether or not the detector should consider this event * as handled. If an event was not handled, the detector * will continue to accumulate movement until an event is * handled. This can be useful if an application, for example, * only wants to update scaling factors if the change is * greater than 0.01. */ @Override public boolean onScale(ScaleGestureDetector detector) { return false; } /** * Responds to the beginning of a scaling gesture. Reported by * new pointers going down. * * @param detector The detector reporting the event - use this to * retrieve extended info about event state. * @return Whether or not the detector should continue recognizing * this gesture. For example, if a gesture is beginning * with a focal point outside of a region where it makes * sense, onScaleBegin() may return false to ignore the * rest of the gesture. */ @Override public boolean onScaleBegin(ScaleGestureDetector detector) { return true; } /** * Responds to the end of a scale gesture. Reported by existing * pointers going up. * <p/> * Once a scale has ended, {@link ScaleGestureDetector#getFocusX()} * and {@link ScaleGestureDetector#getFocusY()} will return focal point * of the pointers remaining on the screen. * * @param detector The detector reporting the event - use this to * retrieve extended info about event state. */ @Override public void onScaleEnd(ScaleGestureDetector detector) { mCameraSource.doZoom(detector.getScaleFactor()); } } }