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。

  /**
   * 关闭预览
   */
  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;
    }
  }


  /**
   * 关闭camera
   */
  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;

/**
 * user:lizhangqu([e-mail])
 * date:2015-09-05
 * time: 10:56
 */
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;

  /**
   * 打开摄像头
   *
   * @param cameraid 摄像头id
   * @return camera
   */
  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;
  }


  /**
   * 打开camera
   *
   * @param holder surfaceholder
   * @throws ioexception ioexception
   */
  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<camera.size> 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);
    }
  }

  /**
   * camera是否打开
   *
   * @return camera是否打开
   */
  public synchronized boolean isopen() {
    return camera != null;
  }

  /**
   * 关闭camera
   */
  public synchronized void closedriver() {
    log.e(tag, "closedriver");
    if (camera != null) {
      camera.release();
      camera = null;
    }
  }

  /**
   * 开始预览
   */
  public synchronized void startpreview() {
    log.e(tag, "startpreview");
    camera thecamera = camera;
    if (thecamera != null && !previewing) {
      thecamera.startpreview();
      previewing = true;
      autofocusmanager = new autofocusmanager(camera);
    }
  }

  /**
   * 关闭预览
   */
  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);
  }

  /**
   * 打开闪光灯
   */
  public synchronized void openlight() {
    log.e(tag, "openlight");
    if (camera != null) {
      parameters = camera.getparameters();
      parameters.setflashmode(camera.parameters.flash_mode_torch);
      camera.setparameters(parameters);
    }
  }

  /**
   * 关闭闪光灯
   */
  public synchronized void offlight() {
    log.e(tag, "offlight");
    if (camera != null) {
      parameters = camera.getparameters();
      parameters.setflashmode(camera.parameters.flash_mode_off);
      camera.setparameters(parameters);
    }
  }

  /**
   * 拍照
   *
   * @param shutter shuttercallback
   * @param raw   picturecallback
   * @param jpeg  picturecallback
   */
  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。