Android系统Camera图片反转的一个问题

一、问题提出

  目前遇到项目问题，Camera预览图像是反的，于是考虑设置180度反转以便正常。

  通过如下两种方式：

  params.setRotation(180); //java部分

  p.set(CameraParameters::KEY_ROTATION,180); //C部分

  发现应用部分takepicture出来数据都没有变化。

代码片段如下：

Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
/*              
Matrix matrix = new Matrix();  
matrix.setRotate(180);
int width = bitmap.getWidth();  
int height = bitmap.getHeight(); 
bitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
*/               
File out = new File("/data/");
if (!out.exists()) {
  out.mkdirs();
}
out = new File("/data/", "1.jpg");
try {
  FileOutputStream outStream = new FileOutputStream(out);
  bitmap.compress(CompressFormat.JPEG, 100, outStream);
  outStream.close();
} catch (Exception e) {
  e.printStackTrace();
}

  上边屏蔽部分打开后ok，屏蔽后有问题；屏蔽部分完成反转功能，证明图片本身有问题。

二、逐层排查

1.frameworks/av/services/camera/libcameraservice/CameraClient.cpp

void CameraClient::dataCallback(int32_t msgType,
        const sp<IMemory>& dataPtr, camera_frame_metadata_t *metadata, void* user) {
  int takepicture_fd;
  takepicture_fd = open("/data/tankai.jpg",O_WRONLY|O_CREAT,00700);
  ALOGD("TK---------->>>>JPEG,dataPtr->size() is %d,takepicture_fd is %d\n",dataPtr->size(),takepicture_fd);
  ALOGD("TK---------->>>>JPEG,dataPtr->size() is 0x%x\n",dataPtr->pointer());
  int write_len = write(takepicture_fd, dataPtr->pointer(), dataPtr->size());
  close(takepicture_fd);
  ALOGD("TK--------_>>>>>>ok\n");
}

2.frameworks/av/camera/Camera.cpp

void Camera::dataCallback(int32_t msgType, const sp<IMemory>& dataPtr,
                          camera_frame_metadata_t *metadata)
{
  int takepicture_fd;
  takepicture_fd = open("/data/tankai_CPP.jpg",O_WRONLY|O_CREAT,00700);
  ALOGD("TK---CPP------->>>>JPEG,dataPtr->size() is %d,takepicture_fd is %d\n",dataPtr->size(),takepicture_fd);
  ALOGD("TK->>>>CPP---->>>>>dataPtr->pointer() is 0x%x",dataPtr->pointer());
  int write_len = write(takepicture_fd, dataPtr->pointer(), dataPtr->size());
  close(takepicture_fd);
  ALOGD("TK---CPP-----_>>>>>>ok\n");
}

3.frameworks/base/core/jni/android_hardware_Camera.cpp

void JNICameraContext::copyAndPost(JNIEnv* env, const sp<IMemory>& dataPtr, int msgType)
{
  jbyteArray obj = NULL;
  obj = env->NewByteArray(size);
  //add by tankai 
  int takepicture_fd;
  takepicture_fd = open("/data/tankai_jni2.jpg",O_WRONLY|O_CREAT,00700);
  ALOGD("TK-------JNI2--->>>>JPEG,size is %d,takepicture_fd is %d\n",size,takepicture_fd);
  ALOGD("TK----->>>>JNI2------>>>>>>data is 0x%x",data);
  int write_len = write(takepicture_fd, data, size);
  close(takepicture_fd);
  ALOGD("TK----JNI2----_>>>>>>ok\n");
  //end tankai
  env->SetByteArrayRegion(obj, 0, size, data);
  //add by tankai
  takepicture_fd = open("/data/tankai_jni3.jpg",O_WRONLY|O_CREAT,00700);
  ALOGD("TK-------JNI3--->>>>JPEG,size is %d,takepicture_fd is %d\n",size,takepicture_fd);
  jbyte * olddata = (jbyte*)env->GetByteArrayElements(obj, 0);
  char* bytearr = (char*)olddata;
  ALOGD("TK----->>>>JNI3------>>>>>>obj is 0x%x,bytearr is 0x%x",obj,bytearr);
  write_len = write(takepicture_fd, bytearr, size);
  close(takepicture_fd);
  ALOGD("TK----JNI3----_>>>>>>ok\n");
  //end tankai
  //调用mCameraJClass的fields.post_event方法，参数为后边的5个
  env->CallStaticVoidMethod(mCameraJClass, fields.post_event,
            mCameraJObjectWeak, msgType, 0, 0, obj); 
}

4.frameworks/base/core/java/android/hardware/Camera.java

public void handleMessage(Message msg) {
  case CAMERA_MSG_COMPRESSED_IMAGE:
    //add by tankai
    Log.d(TAG,"TK-------->>>>>>java callback");
    Bitmap bitmap = BitmapFactory.decodeByteArray(((byte[])msg.obj), 0, ((byte[])msg.obj).length);
    Log.d(TAG,"TK----->>>>((byte[])msg.obj) is 0x%x" + ((byte[])msg.obj));
    String path = "/data/";
    String fileName = "tankai_java.jpg";
    File out = new File(path);
    if (!out.exists()) {
      out.mkdirs();
    }
    out = new File(path, fileName);
    try {
      FileOutputStream outStream = new FileOutputStream( out);
      bitmap.compress(CompressFormat.JPEG, 100,outStream);
      outStream.close();
      Log.d(TAG,"TK-------->>>>>>java callback>>>>ok");
    } catch (Exception e) {
      Log.d(TAG,"TK-------->>>>>>java callback>>>>fail");
      e.printStackTrace();
    }
    //end tankai
}

结果，当设置180度反转后，1-3中所存图片都为正；4为反。

三、原因

1.java部分使用bitmap存文件，没有直接保存；可能是这个原因。

2.修改应用程序中存JPEG文件的方式：

File ret = null;
BufferedOutputStream stream = null;
try {
  ret = new File("/data/1.jpg");
  FileOutputStream fstream = new FileOutputStream(ret);
  stream = new BufferedOutputStream(fstream);
  stream.write(data);
} catch (Exception e) {
  // log.error("helper:get file from byte process error!");  
  e.printStackTrace();
} finally {
  if (stream != null) {
    try {
      stream.close();
    } catch (IOException e) {
      // log.error("helper:get file from byte process error!");  
      e.printStackTrace();
    }
  }
}

结果，图片变正。

3.结论

问题出在bitmap转换上。

四、读取JPEG文件EXIF信息的ORIENTATION字段

1.源码

private int getBitmapDegree(String path) {
    int degree = 0;
    try {
        // 从指定路径下读取图片，并获取其EXIF信息
        ExifInterface exifInterface = new ExifInterface(path);
        // 获取图片的旋转信息
        int orientation = exifInterface.getAttributeInt(ExifInterface.TAG_ORIENTATION,
                ExifInterface.ORIENTATION_NORMAL);
        switch (orientation) {
        case ExifInterface.ORIENTATION_ROTATE_90:
            degree = 90;
            break;
        case ExifInterface.ORIENTATION_ROTATE_180:
            degree = 180;
            break;
        case ExifInterface.ORIENTATION_ROTATE_270:
            degree = 270;
            break;
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    return degree;
}
result = getBitmapDegree("/data/tankai_CPP.jpg");
Log.d("TKTK","TK------>>>>>>>/data/tankai_CPP is " + result);


result = getBitmapDegree("/data/tankai_jni.jpg");
Log.d("TKTK","TK------>>>>>>>/data/tankai_jni1 is " + result);


result = getBitmapDegree("/data/tankai_jni2.jpg");
Log.d("TKTK","TK------>>>>>>>/data/tankai_jni2 is " + result);


result = getBitmapDegree("/data/tankai_jni3.jpg");
Log.d("TKTK","TK------>>>>>>>/data/tankai_jni3 is " + result);


result = getBitmapDegree("/data/tankai_java.jpg");
Log.d("TKTK","TK------>>>>>>>/data/tankai_java is " + result);


result = getBitmapDegree("/data/1.jpg");
Log.d("TKTK","TK------>>>>>>>/data/1.jpg is " + result);

2.结果

正常显示时该字段为180，没有变正的该字段为0。

五、结论

Android系统中Camera拍照时setRotation在各个平台功能不统一：有些平台会直接操作图片的存储地址，将数据反写；但绝大多数平台只是修改了JPEG编码时EXIF头部的ORIENTATION字段。