Android CameraManager scan qr code to open the flash implementation

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 = 480;
    private static final int MAX_FRAME_HEIGHT = 360;

    private static CameraManager cameraManager;

    static final int SDK_INT; // Later we can use Build.VERSION.SDK_INT

    static {
        int sdkInt;
        try {
            sdkInt = Integer.parseInt(Build.VERSION.SDK);
        } catch (NumberFormatException nfe) {
            // Just to be safe
            sdkInt = 10000;
        }
        SDK_INT = sdkInt;
    }

    private final Context context;
    private final CameraConfigurationManager configManager;
    private Camera camera;
    private Rect framingRect;
    private Rect framingRectInPreview;
    private boolean initialized;
    private boolean previewing;
    private final boolean useOneShotPreviewCallback;
    /**
     * 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;
    /**
     * Autofocus callbacks arrive here, and are dispatched to the Handler which requested them.
     */
    private final AutoFocusCallback autoFocusCallback;

    /**
     * Initializes this static object with the Context of the calling Activity.
     *
     * @param context The Activity which wants to use the camera.
     */
    public static void init(Context context) {
        if (cameraManager == null) {
            cameraManager = new CameraManager(context);
        }
    }

    /**
     * Gets the CameraManager singleton instance.
     *
     * @return A reference to the CameraManager singleton.
     */
    public static CameraManager get() {
        return cameraManager;
    }

    private CameraManager(Context context) {

        this.context = context;
        this.configManager = new CameraConfigurationManager(context);

        // Camera.setOneShotPreviewCallback() has a race condition in Cupcake, so we use the older
        // Camera.setPreviewCallback() on 1.5 and earlier. For Donut and later, we need to use
        // the more efficient one shot callback, as the older one can swamp the system and cause it
        // to run out of memory. We can't use SDK_INT because it was introduced in the Donut SDK.
        //useOneShotPreviewCallback = Integer.parseInt(Build.VERSION.SDK) > Build.VERSION_CODES.CUPCAKE;
        useOneShotPreviewCallback = Integer.parseInt(Build.VERSION.SDK) > 3; // 3 = Cupcake

        previewCallback = new PreviewCallback(configManager, useOneShotPreviewCallback);
        autoFocusCallback = new AutoFocusCallback();
    }

    /**
     * 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.
     */
    public void openDriver(SurfaceHolder holder) throws IOException {
        if (camera == null) {
            camera = Camera.open();
            if (camera == null) {
                throw new IOException();
            }
            camera.setPreviewDisplay(holder);

            if (!initialized) {
                initialized = true;
                configManager.initFromCameraParameters(camera);
            }
            configManager.setDesiredCameraParameters(camera);

            //FIXME
            //     SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
           
//      if (prefs.getBoolean(PreferencesActivity.KEY_FRONT_LIGHT, false)) {
//        FlashlightManager.enableFlashlight();
//      }
            FlashlightManager.enableFlashlight();
        }
    }

    /**
     * Closes the camera driver if still in use.
     */
    public void closeDriver() {
        if (camera != null) {
            FlashlightManager.disableFlashlight();
            camera.release();
            camera = null;
        }
    }

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

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

    /**
     * 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 void requestPreviewFrame(Handler handler, int message) {
        if (camera != null && previewing) {
            previewCallback.setHandler(handler, message);
            if (useOneShotPreviewCallback) {
                camera.setOneShotPreviewCallback(previewCallback);
            } else {
                camera.setPreviewCallback(previewCallback);
            }
        }
    }

    /**
     * Asks the camera hardware to perform an autofocus.
     *
     * @param handler The Handler to notify when the autofocus completes.
     * @param message The message to deliver.
     */
    public void requestAutoFocus(Handler handler, int message) {
        if (camera != null && previewing) {
            autoFocusCallback.setHandler(handler, message);
            //Log.d(TAG, "Requesting auto-focus callback");
            camera.autoFocus(autoFocusCallback);
        }
    }

    /**
     * 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 Rect getFramingRect() {
        Point screenResolution = configManager.getScreenResolution();
        if (screenResolution == null)
            return null;
        if (framingRect == null) {
            if (camera == null) {
                return null;
            }

            //修改之后
            int width = screenResolution.x * 7 / 10;
            int height = screenResolution.y * 7 / 10;

            if (height >= width) { //竖屏
                height = width;
            } else { //黑屏
                width = height;
            }

            int leftOffset = (screenResolution.x - width) / 2;
            int topOffset = (screenResolution.y - height) / 2;
            framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);

        }
        return framingRect;
    }
//  public Rect getFramingRect() {
//    Point screenResolution = configManager.getScreenResolution();
//    if (framingRect == null) {
//      if (camera == null) {
//        return null;
//      }
//      int width = screenResolution.x * 3 / 4;
//      if (width < MIN_FRAME_WIDTH) {
//        width = MIN_FRAME_WIDTH;
//      } else if (width > MAX_FRAME_WIDTH) {
//        width = MAX_FRAME_WIDTH;
//      }
//      int height = screenResolution.y * 3 / 4;
//      if (height < MIN_FRAME_HEIGHT) {
//        height = MIN_FRAME_HEIGHT;
//      } else if (height > MAX_FRAME_HEIGHT) {
//        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;
//  }

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

    /**
     * Converts the result points from still resolution coordinates to screen coordinates.
     *
     * @param points The points returned by the Reader subclass through Result.getResultPoints().
     * @return An array of Points scaled to the size of the framing rect and offset appropriately
     *         so they can be drawn in screen coordinates.
     */
  /*
  public Point[] convertResultPoints(ResultPoint[] points) {
    Rect frame = getFramingRectInPreview();
    int count = points.length;
    Point[] output = new Point[count];
    for (int x = 0; x < count; x++) {
      output[x] = new Point();
      output[x].x = frame.left + (int) (points[x].getX() + 0.5f);
      output[x].y = frame.top + (int) (points[x].getY() + 0.5f);
    }
    return output;
  }
   */

    /**
     * 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();
        int previewFormat = configManager.getPreviewFormat();
        String previewFormatString = configManager.getPreviewFormatString();
        switch (previewFormat) {
            // This is the standard Android format which all devices are REQUIRED to support.
            // In theory, it's the only one we should ever care about.
            case PixelFormat.YCbCr_420_SP:
                // This format has never been seen in the wild, but is compatible as we only care
                // about the Y channel, so allow it.
            case PixelFormat.YCbCr_422_SP:
                return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top,
                        rect.width(), rect.height());
            default:
                // The Samsung Moment incorrectly uses this variant instead of the 'sp' version.
                // Fortunately, it too has all the Y data up front, so we can read it.
                if ("yuv420p".equals(previewFormatString)) {
                    return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top,
                            rect.width(), rect.height());
                }
        }
        throw new IllegalArgumentException("Unsupported picture format: " +
                previewFormat + '/' + previewFormatString);
    }

    public Context getContext() {
        return context;
    }

	//是否打开闪光灯
    public boolean isFlashlightOn() {
        try {
            Camera.Parameters parameters = camera.getParameters();
            String flashMode = parameters.getFlashMode();
            if (flashMode.equals(android.hardware.Camera.Parameters.FLASH_MODE_TORCH)) {
                return true;
            } else {
                return false;
            }
        } catch (Exception e) {
            return false;
        }
    }

    /**
     * 闪光灯开关
     */
    public void flashlightUtils() {
        Log.d("cameraFlash", "is flash on>>>>>>>" + isFlashlightOn());
        if (isFlashlightOn()) {
            closesLight();
        } else {
            openLight();
        }
    }
	//打开闪光灯
    private void openLight() {
        if (camera != null) {
            //打开闪光灯
            Camera.Parameters parameter = camera.getParameters();
            parameter.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
            camera.setParameters(parameter);
        }
    }
	//关闭闪光灯
    private void closesLight() {
        if (camera != null) {
            //关闭闪光灯
            Camera.Parameters parameter = camera.getParameters();
            parameter.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
            camera.setParameters(parameter);
        }
    }

}
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