Android CameraManager类详解

本文实例为大家分享了Android CameraManager类的具体代码，供大家参考，具体内容如下

先看代码：

  private SurfaceView mSurfaceView;
  private SurfaceHolder mSurfaceHolder;
  private CameraManager cameraManager;

    cameraManager = new CameraManager(this);
    mSurfaceView = (SurfaceView) findViewById(R.id.java_surface_view);
    mSurfaceHolder = mSurfaceView.getHolder();

    // mSurfaceView 不需要自己的缓冲区
    mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    // mSurfaceView添加回调
    mSurfaceHolder.addCallback(new SurfaceHolder.Callback() {
      @Override
      public void surfaceCreated(SurfaceHolder holder) { //SurfaceView创建
 try {
   cameraManager.openDriver(mSurfaceHolder);
   cameraManager.startPreview();
 } catch (IOException e) {
   e.printStackTrace();
 }
      }

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

      }

      @Override
      public void surfaceDestroyed(SurfaceHolder holder) { //SurfaceView销毁
 holder.removeCallback(this); // Camera is being used after Camera.release() was called
 cameraManager.stopPreview();
 cameraManager.closeDriver();

      }
    });

自定义一个 CameraManager 类，在关闭当前页面，释放camera资源时偶尔报错

Camera is being used after Camera.release() was called

第一次，加了一句 holder.removeCallback(this); 运行发现还是时不时出现报错。

第二次在释放 camera前加  camera.setPreviewCallback(null); 问题解决。

  
  public synchronized void stopPreview() {
    Log.e(TAG, "stopPreview");
    if (autoFocusManager != null) {
      autoFocusManager.stop();
      autoFocusManager = null;
    }
    if (camera != null && previewing) {
      camera.stopPreview();
      camera.setPreviewCallback(null); // Camera is being used after Camera.release() was called
      previewing = false;
    }
  }


  
  public synchronized void closeDriver() {
    Log.e(TAG, "closeDriver");
    if (camera != null) {
      camera.release();
      camera = null;
    }
  }

附：CameraManager类：

package com.lemoncome.facedetection;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.ImageFormat;
import android.graphics.Matrix;
import android.hardware.Camera;
import android.util.Log;
import android.view.Display;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.WindowManager;

import java.io.IOException;
import java.util.List;


public class CameraManager implements Camera.PreviewCallback {
  private static final String TAG = CameraManager.class.getName();
  private Camera camera;
  private Camera.Parameters parameters;
  private AutoFocusManager autoFocusManager;
  private int requestedCameraId = -1;
  private Context mContext;

  private boolean initialized;
  private boolean previewing;

  
  public Camera open(int cameraId) {
    int numCameras = Camera.getNumberOfCameras();
    if (numCameras == 0) {
      Log.e(TAG, "No cameras!");
      return null;
    }
    boolean explicitRequest = cameraId >= 0;
    if (!explicitRequest) {
      // Select a camera if no explicit camera requested
      int index = 0;
      while (index < numCameras) {
 Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
 Camera.getCameraInfo(index, cameraInfo);
 if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {
   break;
 }
 index++;
      }
      cameraId = index;
    }
    Camera camera;
    if (cameraId < numCameras) {
      Log.e(TAG, "Opening camera #" + cameraId);
      camera = Camera.open(cameraId);
    } else {
      if (explicitRequest) {
 Log.e(TAG, "Requested camera does not exist: " + cameraId);
 camera = null;
      } else {
 Log.e(TAG, "No camera facing back; returning camera #0");
 camera = Camera.open(0);
      }
    }
    int rotation = getDisplayOrientation();
    camera.setDisplayOrientation(rotation);
    camera.setPreviewCallback(this);
    return camera;
  }

  public int getDisplayOrientation() {
    Display display = ((WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
    int rotation = display.getRotation();
    int degrees = 0;
    switch (rotation) {
      case Surface.ROTATION_0:
 degrees = 0;
 break;
      case Surface.ROTATION_90:
 degrees = 90;
 break;
      case Surface.ROTATION_180:
 degrees = 180;
 break;
      case Surface.ROTATION_270:
 degrees = 270;
 break;
    }

    Camera.CameraInfo camInfo =
 new Camera.CameraInfo();
    Camera.getCameraInfo(Camera.CameraInfo.CAMERA_FACING_BACK, camInfo);

    int result = (camInfo.orientation - degrees + 360) % 360;
    return result;
  }

  public CameraManager(Context context) {
    mContext = context;
  }


  
  public synchronized void openDriver(SurfaceHolder holder)
      throws IOException {
    Log.e(TAG, "openDriver");
    Camera theCamera = camera;
    if (theCamera == null) {
      theCamera = open(requestedCameraId);
      if (theCamera == null) {
 throw new IOException();
      }
      camera = theCamera;
    }
    theCamera.setPreviewDisplay(holder);

    if (!initialized) {
      initialized = true;
      parameters = camera.getParameters();
      List previewSizes = parameters.getSupportedPreviewSizes();

      int w = 800;
      int h = 600;
      for (Camera.Size size : previewSizes) {
 Log.e("TAG", "previewSizes width:" + size.width);
 Log.e("TAG", "previewSizes height:" + size.height);
 if (size.width - w <= 100 & size.width >= w) {
   w = size.width;
   h = size.height;
   break;
 }
      }

      parameters.setPreviewSize(w, h);
      parameters.setPictureFormat(ImageFormat.JPEG);
      parameters.setJpegQuality(100);
      parameters.setPictureSize(800, 600);
      theCamera.setParameters(parameters);
    }
  }

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

  
  public synchronized void closeDriver() {
    Log.e(TAG, "closeDriver");
    if (camera != null) {
      camera.release();
      camera = null;
    }
  }

  
  public synchronized void startPreview() {
    Log.e(TAG, "startPreview");
    Camera theCamera = camera;
    if (theCamera != null && !previewing) {
      theCamera.startPreview();
      previewing = true;
      autoFocusManager = new AutoFocusManager(camera);
    }
  }

  
  public synchronized void stopPreview() {
    Log.e(TAG, "stopPreview");
    if (autoFocusManager != null) {
      autoFocusManager.stop();
      autoFocusManager = null;
    }
    if (camera != null && previewing) {
      camera.stopPreview();
      camera.setPreviewCallback(null); // Camera is being used after Camera.release() was called
      previewing = false;
    }
  }

  public void setPreviewCallback(Camera.PreviewCallback cb) {
    camera.setoneShotPreviewCallback(this);
  }

  
  public synchronized void openLight() {
    Log.e(TAG, "openLight");
    if (camera != null) {
      parameters = camera.getParameters();
      parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
      camera.setParameters(parameters);
    }
  }

  
  public synchronized void offLight() {
    Log.e(TAG, "offLight");
    if (camera != null) {
      parameters = camera.getParameters();
      parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
      camera.setParameters(parameters);
    }
  }

  
  public synchronized void takePicture(final Camera.ShutterCallback shutter, final Camera.PictureCallback raw,
final Camera.PictureCallback jpeg) {
    camera.takePicture(shutter, raw, jpeg);
  }

  @Override
  public void onPreviewframe(byte[] bytes, Camera camera) {

  }

  private Bitmap reSize(byte[] data) {
    Log.i(TAG, "myJpegCallback:onPictureTaken...");
    Bitmap cutMap = BitmapFactory.decodeByteArray(data, 0, data.length);//data是字节数据，将其解析成位图
    //设置FOCUS_MODE_CONTINUOUS_VIDEO)之后，myParam.set("rotation", 90)失效。图片竟然不能旋转了，故这里要旋转下
    Matrix matrix = new Matrix();
    matrix.postRotate((float) 90.0);
    Bitmap rotaBitmap = Bitmap.createBitmap(cutMap, 0, 0, cutMap.getWidth(), cutMap.getHeight(), matrix, false);

    //旋转后rotaBitmap是960×1280.预览surfaview的大小是540×800
    //将960×1280缩放到540×800
    Bitmap sizeBitmap = Bitmap.createScaledBitmap(rotaBitmap, 540, 800, true);
    Bitmap rectBitmap = Bitmap.createBitmap(sizeBitmap, 100, 200, 300, 300);//截取
    return rectBitmap;
  }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。