我正在开发一个应用程序,需要在拍摄后从图片中访问像素数组。主要活动如下。我有大量的Java经验,但过去在屏幕上显示图像的经验非常有限。我看到字节数组被传递给图片回调方法,但我不知道它是如何格式化的。如何从捕获的图像中获取包含RGB分量的像素阵列?我试图通过堆栈溢出论坛找到这个,但我得到了几百页的结果,只搜索了前10个左右,所以我很抱歉,如果已经被问过,我只是没有看到它。
public class ConverterActivity extends Activity
{
private Camera mCamera;
private CameraPreview mPreview;
private PictureCallback mPicture = new PictureCallback() {
private String TAG;
@Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null){
// Log.d(TAG, "Error creating media file, check storage permissions: " +
// e.getMessage());
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
};
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Add a listener to the Capture button
Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View v) {
// get an image from the camera
mCamera.takePicture(null, null, mPicture);
}
}
);
// Create an instance of Camera
mCamera = Camera.open(this.getBackCamera());
// Create our Preview view and set it as the content of our activity.
mPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
}
@Override
protected void onPause()
{
super.onPause();
releaseCamera(); // release the camera immediately on pause event
}
private void releaseCamera(){
if (mCamera != null){
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type){
return Uri.fromFile(getOutputMediaFile(type));
}
/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "MyCameraApp");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE){
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_"+ timeStamp + ".jpg");
} else if(type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"VID_"+ timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
public int getBackCamera()
{
int numCameras = Camera.getNumberOfCameras();
CameraInfo cInfo = new CameraInfo();
for (int i = 0; i < numCameras; i++)
{
Camera.getCameraInfo(i, cInfo);
if (cInfo.facing == CameraInfo.CAMERA_FACING_BACK)
{
return i;
}
}
return -1;
}
}
答案 0 :(得分:0)
如果您使用以下代码拍摄照片:
imgFile = new File(Environment.getExternalStorageDirectory () + "/somefolder/" + name + ".jpg");
String fileName = imgFile.getAbsolutePath();
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(android.provider.MediaStore.EXTRA_OUTPUT, Uri.fromFile(new File(fileName)));
startActivityForResult(intent, REQUEST_FROM_CAMERA);
然后你应该能够,当你从这个意图中得到结果时,使用这样的代码来访问位图
if (imgFile.exists()) {
String fileName = file.getAbsolutePath();
BitmapFactory.Options opts = new BitmapFactory.Options();
Bitmap bm;
opts.inJustDecodeBounds = false;
bm = BitmapFactory.decodeFile(fileName, opts);
return bm;
}
else return null;
然后你可以使用bitmapfactory工具,比如压缩流,然后 转换为byte []
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 100, stream); // 100 = max quality
byte[] byteArray = stream.toByteArray();