CameraManager.java

/*
 * Copyright 2012-2014 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.graybits.wallet.common;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;


import android.annotation.SuppressLint;
import android.graphics.Rect;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.PreviewCallback;
import android.view.SurfaceHolder;

import com.google.zxing.PlanarYUVLuminanceSource;

/**
 * @author Andreas Schildbach
 */
public final class CameraManager {
    private static final int MIN_FRAME_SIZE = 240;
    private static final int MAX_FRAME_SIZE = 600;
    private static final int MIN_PREVIEW_PIXELS = 470 * 320; // normal screen
    private static final int MAX_PREVIEW_PIXELS = 1280 * 720;

    private Camera camera;
    private Camera.Size cameraResolution;
    private Rect frame;
    private Rect framePreview;

//    private static final Logger log = LoggerFactory.getLogger(CameraManager.class);

    public Rect getFrame() {
        return frame;
    }

    public Rect getFramePreview() {
        return framePreview;
    }

    public Camera open(final SurfaceHolder holder, final boolean continuousAutoFocus) throws IOException {
        // try back-facing camera
        camera = Camera.open();

        // fall back to using front-facing camera
        if (camera == null) {
            final int cameraCount = Camera.getNumberOfCameras();
            final CameraInfo cameraInfo = new CameraInfo();

            // search for front-facing camera
            for (int i = 0; i < cameraCount; i++) {
                Camera.getCameraInfo(i, cameraInfo);
                if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
                    camera = Camera.open(i);
                    break;
                }
            }
        }

        camera.setPreviewDisplay(holder);

        final Camera.Parameters parameters = camera.getParameters();

        final Rect surfaceFrame = holder.getSurfaceFrame();
        cameraResolution = findBestPreviewSizeValue(parameters, surfaceFrame);

        final int surfaceWidth = surfaceFrame.width();
        final int surfaceHeight = surfaceFrame.height();

        final int rawSize = Math.min(surfaceWidth * 2 / 3, surfaceHeight * 2 / 3);
        final int frameSize = Math.max(MIN_FRAME_SIZE, Math.min(MAX_FRAME_SIZE, rawSize));

        final int leftOffset = (surfaceWidth - frameSize) / 2;
        final int topOffset = (surfaceHeight - frameSize) / 2;
        frame = new Rect(leftOffset, topOffset, leftOffset + frameSize, topOffset + frameSize);
        framePreview = new Rect(frame.left * cameraResolution.width / surfaceWidth, frame.top * cameraResolution.height / surfaceHeight, frame.right
                * cameraResolution.width / surfaceWidth, frame.bottom * cameraResolution.height / surfaceHeight);

        final String savedParameters = parameters == null ? null : parameters.flatten();

        try {
            setDesiredCameraParameters(camera, cameraResolution, continuousAutoFocus);
        } catch (final RuntimeException x) {
            if (savedParameters != null) {
                final Camera.Parameters parameters2 = camera.getParameters();
                parameters2.unflatten(savedParameters);
                try {
                    camera.setParameters(parameters2);
                    setDesiredCameraParameters(camera, cameraResolution, continuousAutoFocus);
                } catch (final RuntimeException x2) {
//                    log.info("problem setting camera parameters", x2);
                }
            }
        }

        camera.startPreview();

        return camera;
    }

    public void close() {
        if (camera != null) {
            camera.stopPreview();
            camera.release();
        }
    }

    private static final Comparator<Camera.Size> numPixelComparator = new Comparator<Camera.Size>() {
        @Override
        public int compare(final Camera.Size size1, final Camera.Size size2) {
            final int pixels1 = size1.height * size1.width;
            final int pixels2 = size2.height * size2.width;

            if (pixels1 < pixels2)
                return 1;
            else if (pixels1 > pixels2)
                return -1;
            else
                return 0;
        }
    };

    private static Camera.Size findBestPreviewSizeValue(final Camera.Parameters parameters, Rect surfaceResolution) {
        if (surfaceResolution.height() > surfaceResolution.width())
            surfaceResolution = new Rect(0, 0, surfaceResolution.height(), surfaceResolution.width());

        final float screenAspectRatio = (float) surfaceResolution.width() / (float) surfaceResolution.height();

        final List<Camera.Size> rawSupportedSizes = parameters.getSupportedPreviewSizes();
        if (rawSupportedSizes == null)
            return parameters.getPreviewSize();

        // sort by size, descending
        final List<Camera.Size> supportedPreviewSizes = new ArrayList<Camera.Size>(rawSupportedSizes);
        Collections.sort(supportedPreviewSizes, numPixelComparator);

        Camera.Size bestSize = null;
        float diff = Float.POSITIVE_INFINITY;

        for (final Camera.Size supportedPreviewSize : supportedPreviewSizes) {
            final int realWidth = supportedPreviewSize.width;
            final int realHeight = supportedPreviewSize.height;
            final int realPixels = realWidth * realHeight;
            if (realPixels < MIN_PREVIEW_PIXELS || realPixels > MAX_PREVIEW_PIXELS)
                continue;

            final boolean isCandidatePortrait = realWidth < realHeight;
            final int maybeFlippedWidth = isCandidatePortrait ? realHeight : realWidth;
            final int maybeFlippedHeight = isCandidatePortrait ? realWidth : realHeight;
            if (maybeFlippedWidth == surfaceResolution.width() && maybeFlippedHeight == surfaceResolution.height())
                return supportedPreviewSize;

            final float aspectRatio = (float) maybeFlippedWidth / (float) maybeFlippedHeight;
            final float newDiff = Math.abs(aspectRatio - screenAspectRatio);
            if (newDiff < diff) {
                bestSize = supportedPreviewSize;
                diff = newDiff;
            }
        }

        if (bestSize != null)
            return bestSize;
        else
            return parameters.getPreviewSize();
    }

    @SuppressLint("InlinedApi")
    private static void setDesiredCameraParameters(final Camera camera, final Camera.Size cameraResolution, final boolean continuousAutoFocus) {
        final Camera.Parameters parameters = camera.getParameters();
        if (parameters == null)
            return;

        final List<String> supportedFocusModes = parameters.getSupportedFocusModes();
        final String focusMode = continuousAutoFocus ? findValue(supportedFocusModes, Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE,
                Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO, Camera.Parameters.FOCUS_MODE_AUTO, Camera.Parameters.FOCUS_MODE_MACRO) : findValue(
                supportedFocusModes, Camera.Parameters.FOCUS_MODE_AUTO, Camera.Parameters.FOCUS_MODE_MACRO);
        if (focusMode != null)
            parameters.setFocusMode(focusMode);

        parameters.setPreviewSize(cameraResolution.width, cameraResolution.height);

        camera.setParameters(parameters);
    }

    public void requestPreviewFrame(final PreviewCallback callback) {
        camera.setOneShotPreviewCallback(callback);
    }

    public PlanarYUVLuminanceSource buildLuminanceSource(final byte[] data) {
        return new PlanarYUVLuminanceSource(data, cameraResolution.width, cameraResolution.height, framePreview.left, framePreview.top,
                framePreview.width(), framePreview.height(), false);
    }

    public void setTorch(final boolean enabled) {
        if (enabled != getTorchEnabled(camera))
            setTorchEnabled(camera, enabled);
    }

    private static boolean getTorchEnabled(final Camera camera) {
        final Camera.Parameters parameters = camera.getParameters();
        if (parameters != null) {
            final String flashMode = camera.getParameters().getFlashMode();
            return flashMode != null && (Camera.Parameters.FLASH_MODE_ON.equals(flashMode) || Camera.Parameters.FLASH_MODE_TORCH.equals(flashMode));
        }

        return false;
    }

    private static void setTorchEnabled(final Camera camera, final boolean enabled) {
        final Camera.Parameters parameters = camera.getParameters();

        final List<String> supportedFlashModes = parameters.getSupportedFlashModes();
        if (supportedFlashModes != null) {
            final String flashMode;
            if (enabled)
                flashMode = findValue(supportedFlashModes, Camera.Parameters.FLASH_MODE_TORCH, Camera.Parameters.FLASH_MODE_ON);
            else
                flashMode = findValue(supportedFlashModes, Camera.Parameters.FLASH_MODE_OFF);

            if (flashMode != null) {
                camera.cancelAutoFocus(); // autofocus can cause conflict

                parameters.setFlashMode(flashMode);
                camera.setParameters(parameters);
            }
        }
    }

    private static String findValue(final Collection<String> values, final String... valuesToFind) {
        for (final String valueToFind : valuesToFind)
            if (values.contains(valueToFind))
                return valueToFind;

        return null;
    }
}

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <!-- scanner -->
    <color name="scan_mask">#60000000</color>
    <color name="scan_laser">#cc0000</color>
    <color name="scan_dot">#ff6600</color>
    <color name="scan_result_view">#b0000000</color>
    <color name="scan_result_dots">#c099cc00</color>
</resources>

scan_activity.xml

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <FrameLayout android:layout_width="match_parent"
                 android:layout_height="300dp">
        <SurfaceView
                android:id="@+id/scan_activity_preview"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:keepScreenOn="true"/>

        <com.graybits.wallet.common.ScannerView
                android:id="@+id/scan_activity_mask"
                android:layout_width="match_parent"
                android:layout_height="match_parent"/>
    </FrameLayout>

    <EditText
              android:layout_width="match_parent"
              android:layout_height="wrap_content"/>

    <Button
            android:text="Do something"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
</LinearLayout>

ScanFragment.java

package com.graybits.wallet.common;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.hardware.Camera;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Process;
import android.os.Vibrator;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;

import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
import com.google.zxing.PlanarYUVLuminanceSource;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.ResultPoint;
import com.google.zxing.ResultPointCallback;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.QRCodeReader;
import com.graybits.wallet.R;

import java.io.IOException;
import java.util.EnumMap;
import java.util.Map;

import butterknife.InjectView;

/**
 * Created by nasir on 9/15/14.
 */
public class ScanFragment extends BaseFragment implements SurfaceHolder.Callback {
    public static final String INTENT_EXTRA_RESULT = "result";

    private static final long VIBRATE_DURATION = 50L;
    private static final long AUTO_FOCUS_INTERVAL_MS = 2500L;

    private final CameraManager cameraManager = new CameraManager();

    @InjectView(R.id.scan_activity_mask)
    ScannerView scannerView;


    private SurfaceHolder surfaceHolder;
    private Vibrator vibrator;
    private HandlerThread cameraThread;
    private Handler cameraHandler;

    private static final int DIALOG_CAMERA_PROBLEM = 0;

    private static boolean DISABLE_CONTINUOUS_AUTOFOCUS = Build.MODEL.equals("GT-I9100") // Galaxy S2
            || Build.MODEL.equals("SGH-T989") // Galaxy S2
            || Build.MODEL.equals("SGH-T989D") // Galaxy S2 X
            || Build.MODEL.equals("SAMSUNG-SGH-I727") // Galaxy S2 Skyrocket
            || Build.MODEL.equals("GT-I9300") // Galaxy S3
            || Build.MODEL.equals("GT-N7000"); // Galaxy Note

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.scan_activity, null);
        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        vibrator = (Vibrator) getActivity().getSystemService(Context.VIBRATOR_SERVICE);

        cameraThread = new HandlerThread("cameraThread", Process.THREAD_PRIORITY_BACKGROUND);
        cameraThread.start();
        cameraHandler = new Handler(cameraThread.getLooper());
        final SurfaceView surfaceView = (SurfaceView) getView().findViewById(R.id.scan_activity_preview);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    @Override
    public void onResume() {
        super.onResume();
//        cameraThread = new HandlerThread("cameraThread", Process.THREAD_PRIORITY_BACKGROUND);
//        cameraThread.start();
//        cameraHandler = new Handler(cameraThread.getLooper());

//        final SurfaceView surfaceView = (SurfaceView) getView().findViewById(R.id.scan_activity_preview);
//        surfaceHolder = surfaceView.getHolder();
//        surfaceHolder.addCallback(this);
//        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    }

    @Override
    public void onPause() {
        cameraHandler.post(closeRunnable);
        surfaceHolder.removeCallback(this);
        super.onPause();
    }


    @Override
    public void surfaceCreated(final SurfaceHolder holder) {
        cameraHandler.post(openRunnable);
    }

    @Override
    public void surfaceDestroyed(final SurfaceHolder holder) {
    }

    @Override
    public void surfaceChanged(final SurfaceHolder holder, final int format, final int width, final int height) {
    }


    public void handleResult(final Result scanResult, final Bitmap thumbnailImage, final float thumbnailScaleFactor) {
        vibrator.vibrate(VIBRATE_DURATION);

        // superimpose dots to highlight the key features of the qr code
        final ResultPoint[] points = scanResult.getResultPoints();
        if (points != null && points.length > 0) {
            final Paint paint = new Paint();
            paint.setColor(getResources().getColor(R.color.scan_result_dots));
            paint.setStrokeWidth(10.0f);

            final Canvas canvas = new Canvas(thumbnailImage);
            canvas.scale(thumbnailScaleFactor, thumbnailScaleFactor);
            for (final ResultPoint point : points)
                canvas.drawPoint(point.getX(), point.getY(), paint);
        }

        scannerView.drawResultBitmap(thumbnailImage);

        final Intent result = new Intent();
        result.putExtra(INTENT_EXTRA_RESULT, scanResult.getText());
        getActivity().setResult(Activity.RESULT_OK, result);

        new Handler().post(new Runnable() {
            @Override
            public void run() {
                getActivity().finish();
            }
        });
    }

    private final Runnable openRunnable = new Runnable() {
        @Override
        public void run() {
            try {
                final Camera camera = cameraManager.open(surfaceHolder, !DISABLE_CONTINUOUS_AUTOFOCUS);
                camera.setDisplayOrientation(90);

                final Rect framingRect = cameraManager.getFrame();
                final Rect framingRectInPreview = cameraManager.getFramePreview();

                getActivity().runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        scannerView.setFraming(framingRect, framingRectInPreview);
                    }
                });

                final String focusMode = camera.getParameters().getFocusMode();
                final boolean nonContinuousAutoFocus = Camera.Parameters.FOCUS_MODE_AUTO.equals(focusMode)
                        || Camera.Parameters.FOCUS_MODE_MACRO.equals(focusMode);

                if (nonContinuousAutoFocus)
                    cameraHandler.post(new AutoFocusRunnable(camera));

                cameraHandler.post(fetchAndDecodeRunnable);
            } catch (final IOException x) {
//                log.info("problem opening camera", x);
                error(x.getMessage(), x);
//                showDialog(DIALOG_CAMERA_PROBLEM);
                throw new IllegalStateException();
            } catch (final RuntimeException x) {
                error(x.getMessage(), x);

//                log.info("problem opening camera", x);
//                showDialog(DIALOG_CAMERA_PROBLEM);
                throw new IllegalStateException();
            }
        }
    };

    private final Runnable closeRunnable = new Runnable() {
        @Override
        public void run() {
            cameraManager.close();

            // cancel background thread
            cameraHandler.removeCallbacksAndMessages(null);
            cameraThread.quit();
        }
    };

    private final class AutoFocusRunnable implements Runnable {
        private final Camera camera;

        public AutoFocusRunnable(final Camera camera) {
            this.camera = camera;
        }

        @Override
        public void run() {
            camera.autoFocus(new Camera.AutoFocusCallback() {
                @Override
                public void onAutoFocus(final boolean success, final Camera camera) {
                    // schedule again
                    cameraHandler.postDelayed(AutoFocusRunnable.this, AUTO_FOCUS_INTERVAL_MS);
                }
            });
        }
    }

    private final Runnable fetchAndDecodeRunnable = new Runnable() {
        private final QRCodeReader reader = new QRCodeReader();
        private final Map<DecodeHintType, Object> hints = new EnumMap<DecodeHintType, Object>(DecodeHintType.class);

        @Override
        public void run() {
            cameraManager.requestPreviewFrame(new Camera.PreviewCallback() {
                @Override
                public void onPreviewFrame(final byte[] data, final Camera camera) {
                    decode(data);
                }
            });
        }

        private void decode(final byte[] data) {
            final PlanarYUVLuminanceSource source = cameraManager.buildLuminanceSource(data);
            final BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));

            try {
                hints.put(DecodeHintType.NEED_RESULT_POINT_CALLBACK, new ResultPointCallback() {
                    @Override
                    public void foundPossibleResultPoint(final ResultPoint dot) {
                        getActivity().runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                scannerView.addDot(dot);
                            }
                        });
                    }
                });
                final Result scanResult = reader.decode(bitmap, hints);

                final int thumbnailWidth = source.getThumbnailWidth();
                final int thumbnailHeight = source.getThumbnailHeight();
                final float thumbnailScaleFactor = (float) thumbnailWidth / source.getWidth();

                final Bitmap thumbnailImage = Bitmap.createBitmap(thumbnailWidth, thumbnailHeight, Bitmap.Config.ARGB_8888);
                thumbnailImage.setPixels(source.renderThumbnail(), 0, thumbnailWidth, 0, 0, thumbnailWidth, thumbnailHeight);

                getActivity().runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        handleResult(scanResult, thumbnailImage, thumbnailScaleFactor);
                    }
                });
            } catch (final ReaderException x) {
                // retry
                cameraHandler.post(fetchAndDecodeRunnable);
            } finally {
                reader.reset();
            }
        }
    };
}

ScannerView.java

/*
 * Copyright 2012-2014 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.graybits.wallet.common;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;


import android.content.Context;
import android.content.res.Resources;
import android.graphics.*;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.view.View;

import com.google.zxing.ResultPoint;
import com.graybits.wallet.R;


/**
 * @author Andreas Schildbach
 */
public class ScannerView extends View {
    private static final long LASER_ANIMATION_DELAY_MS = 100l;
    private static final int DOT_OPACITY = 0xa0;
    private static final int DOT_SIZE = 8;
    private static final int DOT_TTL_MS = 500;

    private final Paint maskPaint;
    private final Paint laserPaint;
    private final Paint dotPaint;
    private Bitmap resultBitmap;
    private final int maskColor;
    private final int resultColor;
    private final Map<ResultPoint, Long> dots = new HashMap<ResultPoint, Long>(16);
    private Rect frame, framePreview;

    public ScannerView(final Context context, final AttributeSet attrs) {
        super(context, attrs);

        final Resources res = getResources();
        maskColor = res.getColor(R.color.scan_mask);
        resultColor = res.getColor(R.color.scan_result_view);
        final int laserColor = res.getColor(R.color.scan_laser);
        final int dotColor = res.getColor(R.color.scan_dot);

        maskPaint = new Paint();
        maskPaint.setStyle(Style.FILL);

        laserPaint = new Paint();
        laserPaint.setColor(laserColor);
        laserPaint.setStrokeWidth(DOT_SIZE);
        laserPaint.setStyle(Style.STROKE);

        dotPaint = new Paint();
        dotPaint.setColor(dotColor);
        dotPaint.setAlpha(DOT_OPACITY);
        dotPaint.setStyle(Style.STROKE);
        dotPaint.setStrokeWidth(DOT_SIZE);
        dotPaint.setAntiAlias(true);
    }

    public void setFraming(final Rect frame, final Rect framePreview) {
        this.frame = frame;
        this.framePreview = framePreview;

        invalidate();
    }

    public void drawResultBitmap(final Bitmap bitmap) {
        resultBitmap = bitmap;

        invalidate();
    }

    public void addDot(final ResultPoint dot) {
        dots.put(dot, System.currentTimeMillis());

        invalidate();
    }

    @Override
    public void onDraw(final Canvas canvas) {
        if (frame == null)
            return;

        final long now = System.currentTimeMillis();

        final int width = canvas.getWidth();
        final int height = canvas.getHeight();

        // draw mask darkened
        maskPaint.setColor(resultBitmap != null ? resultColor : maskColor);
        canvas.drawRect(0, 0, width, frame.top, maskPaint);
        canvas.drawRect(0, frame.top, frame.left, frame.bottom + 1, maskPaint);
        canvas.drawRect(frame.right + 1, frame.top, width, frame.bottom + 1, maskPaint);
        canvas.drawRect(0, frame.bottom + 1, width, height, maskPaint);

        if (resultBitmap != null) {
            canvas.drawBitmap(resultBitmap, null, frame, maskPaint);
        } else {
            // draw red "laser scanner" to show decoding is active
            final boolean laserPhase = (now / 600) % 2 == 0;
            laserPaint.setAlpha(laserPhase ? 160 : 255);
            canvas.drawRect(frame, laserPaint);

            // draw points
            final int frameLeft = frame.left;
            final int frameTop = frame.top;
            final float scaleX = frame.width() / (float) framePreview.width();
            final float scaleY = frame.height() / (float) framePreview.height();

            for (final Iterator<Map.Entry<ResultPoint, Long>> i = dots.entrySet().iterator(); i.hasNext(); ) {
                final Map.Entry<ResultPoint, Long> entry = i.next();
                final long age = now - entry.getValue();
                if (age < DOT_TTL_MS) {
                    dotPaint.setAlpha((int) ((DOT_TTL_MS - age) * 256 / DOT_TTL_MS));

                    final ResultPoint point = entry.getKey();
                    canvas.drawPoint(frameLeft + (int) (point.getX() * scaleX), frameTop + (int) (point.getY() * scaleY), dotPaint);
                } else {
                    i.remove();
                }
            }

            // schedule redraw
            postInvalidateDelayed(LASER_ANIMATION_DELAY_MS);
        }
    }
}

I tried running this example, but the camera do not seem to be working, I get the first half of the screen black and then nothing happens. Could you please tell me what am i missing