Android Open Source - GlassCounter Camera Manager

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License

The source code is released under:
Apache License
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Java Source Code

/*
 * Copyright (C) 2008 ZXing authors/*www  .j  ava 2  s  . c o  m*/
 * 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.zxing.client.android.camera;

import java.io.IOException;

import android.content.Context;
import android.graphics.Point;
import android.graphics.Rect;
import android.hardware.Camera;
import android.os.Handler;
import android.util.Log;
import android.view.SurfaceHolder;

import com.google.zxing.PlanarYUVLuminanceSource;
import com.google.zxing.client.android.camera.open.OpenCameraInterface;

/**
 * This object wraps the Camera service object and expects to be the only one
 * talking to it. The
 * implementation encapsulates the steps needed to take preview-sized images,
 * which are used for
 * both preview and decoding.
 *
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class CameraManager {

    private static final String TAG = CameraManager.class.getSimpleName();

    private static final int MIN_FRAME_WIDTH = 240;
    private static final int MIN_FRAME_HEIGHT = 240;
    private static final int MAX_FRAME_WIDTH = 1200; // = 5/8 * 1920
    private static final int MAX_FRAME_HEIGHT = 675; // = 5/8 * 1080

    private final Context context;
    private final CameraConfigurationManager configManager;
    private Camera camera;
    private AutoFocusManager autoFocusManager;
    private Rect framingRect;
    private Rect framingRectInPreview;
    private boolean initialized;
    private boolean previewing;
    private int requestedFramingRectWidth;
    private int requestedFramingRectHeight;
    /**
     * Preview frames are delivered here, which we pass on to the registered
     * handler. Make sure to
     * clear the handler so it will only receive one message.
     */
    private final PreviewCallback previewCallback;

    public CameraManager(Context context) {
        this.context = context;
        this.configManager = new CameraConfigurationManager(context);
        previewCallback = new PreviewCallback(configManager);
    }

    /**
     * Opens the camera driver and initializes the hardware parameters.
     *
     * @param holder
     *            The surface object which the camera will draw preview frames
     *            into.
     * @throws IOException
     *             Indicates the camera driver failed to open.
     * @throws InterruptedException
     */
    public synchronized void openDriver(SurfaceHolder holder)
            throws IOException, InterruptedException {
        Camera theCamera = camera;
        if (theCamera == null) {
            theCamera = OpenCameraInterface.open();
            if (theCamera == null) {
                throw new IOException();
            }
            camera = theCamera;
        }
        theCamera.setPreviewDisplay(holder);

        if (!initialized) {
            initialized = true;
            configManager.initFromCameraParameters(theCamera);
            if (requestedFramingRectWidth > 0 && requestedFramingRectHeight > 0) {
                setManualFramingRect(requestedFramingRectWidth,
                        requestedFramingRectHeight);
                requestedFramingRectWidth = 0;
                requestedFramingRectHeight = 0;
            }
        }

        Camera.Parameters parameters = theCamera.getParameters();
        String parametersFlattened = parameters == null ? null : parameters
                .flatten(); // Save these, temporarily
        try {
            configManager.setDesiredCameraParameters(theCamera, false);
        } catch (RuntimeException re) {
            // Driver failed
            Log.w(TAG,
                    "Camera rejected parameters. Setting only minimal safe-mode parameters");
            Log.i(TAG, "Resetting to saved camera params: "
                    + parametersFlattened);
            // Reset:
            if (parametersFlattened != null) {
                parameters = theCamera.getParameters();
                parameters.unflatten(parametersFlattened);
                try {
                    theCamera.setParameters(parameters);
                    configManager.setDesiredCameraParameters(theCamera, true);
                } catch (RuntimeException re2) {
                    // Well, darn. Give up
                    Log.w(TAG,
                            "Camera rejected even safe-mode parameters! No configuration");
                }
            }
        }

    }

    public synchronized boolean isOpen() {
        return camera != null;
    }

    /**
     * Closes the camera driver if still in use.
     */
    public synchronized void closeDriver() {
        if (camera != null) {
            camera.release();
            camera = null;
            // Make sure to clear these each time we close the camera, so that any scanning rect
            // requested by intent is forgotten.
            framingRect = null;
            framingRectInPreview = null;
        }
    }

    /**
     * Asks the camera hardware to begin drawing preview frames to the screen.
     */
    public synchronized void startPreview() {
        Camera theCamera = camera;
        if (theCamera != null && !previewing) {

            theCamera.startPreview();
            previewing = true;
            autoFocusManager = new AutoFocusManager(context, camera);
        }
    }

    /**
     * Tells the camera to stop drawing preview frames.
     */
    public synchronized void stopPreview() {
        if (autoFocusManager != null) {
            autoFocusManager.stop();
            autoFocusManager = null;
        }
        if (camera != null && previewing) {
            camera.stopPreview();
            previewCallback.setHandler(null, 0);
            previewing = false;
        }
    }

    /**
     * Convenience method for
     * {@link com.com.github.barcodeeye.scan.CaptureActivity}
     */
    public synchronized void setTorch(boolean newSetting) {
        if (newSetting != configManager.getTorchState(camera)) {
            if (camera != null) {
                if (autoFocusManager != null) {
                    autoFocusManager.stop();
                }
                configManager.setTorch(camera, newSetting);
                if (autoFocusManager != null) {
                    autoFocusManager.start();
                }
            }
        }
    }

    /**
     * A single preview frame will be returned to the handler supplied. The data
     * will arrive as byte[]
     * in the message.obj field, with width and height encoded as message.arg1
     * and message.arg2,
     * respectively.
     *
     * @param handler
     *            The handler to send the message to.
     * @param message
     *            The what field of the message to be sent.
     */
    public synchronized void requestPreviewFrame(Handler handler, int message) {
        Camera theCamera = camera;
        if (theCamera != null && previewing) {
            previewCallback.setHandler(handler, message);
            theCamera.setOneShotPreviewCallback(previewCallback);
        }
    }

    /**
     * Calculates the framing rect which the UI should draw to show the user
     * where to place the
     * barcode. This target helps with alignment as well as forces the user to
     * hold the device
     * far enough away to ensure the image will be in focus.
     *
     * @return The rectangle to draw on screen in window coordinates.
     */
    public synchronized Rect getFramingRect() {
        if (framingRect == null) {
            if (camera == null) {
                return null;
            }
            Point screenResolution = configManager.getScreenResolution();
            if (screenResolution == null) {
                // Called early, before init even finished
                return null;
            }

            int width = findDesiredDimensionInRange(screenResolution.x,
                    MIN_FRAME_WIDTH, MAX_FRAME_WIDTH);
            int height = findDesiredDimensionInRange(screenResolution.y,
                    MIN_FRAME_HEIGHT, MAX_FRAME_HEIGHT);

            int leftOffset = (screenResolution.x - width) / 2;
            int topOffset = (screenResolution.y - height) / 2;
            framingRect = new Rect(leftOffset, topOffset, leftOffset + width,
                    topOffset + height);
            Log.d(TAG, "Calculated framing rect: " + framingRect);
        }
        return framingRect;
    }

    private static int findDesiredDimensionInRange(int resolution, int hardMin,
            int hardMax) {
        int dim = 5 * resolution / 8; // Target 5/8 of each dimension
        if (dim < hardMin) {
            return hardMin;
        }
        if (dim > hardMax) {
            return hardMax;
        }
        return dim;
    }

    /**
     * Like {@link #getFramingRect} but coordinates are in terms of the preview
     * frame,
     * not UI / screen.
     */
    public synchronized Rect getFramingRectInPreview() {
        if (framingRectInPreview == null) {
            Rect framingRect = getFramingRect();
            if (framingRect == null) {
                return null;
            }
            Rect rect = new Rect(framingRect);
            Point cameraResolution = configManager.getCameraResolution();
            Point screenResolution = configManager.getScreenResolution();
            if (cameraResolution == null || screenResolution == null) {
                // Called early, before init even finished
                return null;
            }
            rect.left = rect.left * cameraResolution.x / screenResolution.x;
            rect.right = rect.right * cameraResolution.x / screenResolution.x;
            rect.top = rect.top * cameraResolution.y / screenResolution.y;
            rect.bottom = rect.bottom * cameraResolution.y / screenResolution.y;
            framingRectInPreview = rect;
        }
        return framingRectInPreview;
    }

    /**
     * Allows third party apps to specify the scanning rectangle dimensions,
     * rather than determine
     * them automatically based on screen resolution.
     *
     * @param width
     *            The width in pixels to scan.
     * @param height
     *            The height in pixels to scan.
     */
    public synchronized void setManualFramingRect(int width, int height) {
        if (initialized) {
            Point screenResolution = configManager.getScreenResolution();
            if (width > screenResolution.x) {
                width = screenResolution.x;
            }
            if (height > screenResolution.y) {
                height = screenResolution.y;
            }
            int leftOffset = (screenResolution.x - width) / 2;
            int topOffset = (screenResolution.y - height) / 2;
            framingRect = new Rect(leftOffset, topOffset, leftOffset + width,
                    topOffset + height);
            Log.d(TAG, "Calculated manual framing rect: " + framingRect);
            framingRectInPreview = null;
        } else {
            requestedFramingRectWidth = width;
            requestedFramingRectHeight = height;
        }
    }

    /**
     * A factory method to build the appropriate LuminanceSource object based on
     * the format
     * of the preview buffers, as described by Camera.Parameters.
     *
     * @param data
     *            A preview frame.
     * @param width
     *            The width of the image.
     * @param height
     *            The height of the image.
     * @return A PlanarYUVLuminanceSource instance.
     */
    public PlanarYUVLuminanceSource buildLuminanceSource(byte[] data,
            int width, int height) {
        Rect rect = getFramingRectInPreview();
        if (rect == null) {
            return null;
        }
        // Go ahead and assume it's YUV rather than die.
        return new PlanarYUVLuminanceSource(data, width, height, rect.left,
                rect.top, rect.width(), rect.height(), false);
    }

}
Java Source Code List
