我正在创建一个自定义相机应用程序（它将包含在一个更大的主应用程序中），该应用程序使用相机 - 视图和图片库预览加载视图 - 因此用户可以拍照或选择一个先前存在的。如果用户确实拍了照片，我只想显示一个确认对话框，如果确认，则将控制权交还给主要活动。我无法存储照片：需要快速将其用作附件，并且一旦通过主要活动发送，请将其丢弃。
当我拍照并且调用onPictureTaken（）时出现问题：它要么不起作用，要么花费很长时间来保存照片。此外，我似乎无法弄清楚如何在现场提取照片，而不将其保存到目录;我计划立即删除目录，但必须有一个更清洁的方式（基本上，我只是想访问该原始字节数组，而不必保存它）。
我希望它是模块化的（在我即将开展的项目中会大量使用相机），我认为这会增加整体延迟。
我关注了Google的开发者Android Guide on Cameras，我的大部分代码都来自那里提供的示例。
我也在使用ActionBarSherlock。
我目前有三个班级：
CameraManager
public class CameraManager {
private static Camera CAMERA;
/** Check if this device has a camera */
public static boolean doesDeviceHaveCamera(Context context) {
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
return true;
}
else {
return false;
}
}
public static Camera getCameraInstance(){
CAMERA = null;
try {
CAMERA = Camera.open();
}
catch (Exception e){
// Camera is not available (in use or does not exist)
}
return CAMERA;
}
}
CameraPreview
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = "CameraPreview";
private SurfaceHolder surfaceHolder;
private Camera camera;
public CameraPreview(Context context, Camera camera) {
super(context);
this.camera = camera;
surfaceHolder = getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); // deprecated setting, but required on Android versions prior to 3.0
}
public void surfaceCreated(SurfaceHolder holder) {
try {
camera.setPreviewDisplay(holder);
camera.startPreview();
}
catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
camera.stopPreview();
camera.release();
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (surfaceHolder.getSurface() == null){
return;
}
try {
camera.stopPreview();
}
catch (Exception e){
// ignore: tried to stop a non-existent preview
}
// set preview size and make any resize, rotate or
// reformatting changes here
camera.setDisplayOrientation(90);
// start preview with new settings
try {
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
}
catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}
CameraActivity
public class CameraActivity extends SherlockActivity {
private static final String TAG = "CameraActivity";
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
private Camera camera;
private CameraPreview preview;
private PictureCallback picture = new PictureCallback() {
@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: media file is null.");
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);
getSupportActionBar().hide();
setContentView(R.layout.camera_view);
/**Get a camera instance**/
if(CameraManager.doesDeviceHaveCamera(this)){
camera = CameraManager.getCameraInstance();
}
else{
return;
}
/**Create a SurfaceView preview (holds the camera feed) and set it to the corresponding XML layout**/
preview = new CameraPreview(this, camera);
FrameLayout previewContainer = (FrameLayout) findViewById(R.id.camera_preview);
previewContainer.addView(preview);
/**Set up a capture button, which takes the picture**/
Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
camera.takePicture(null, null, picture);
}
});
}
/** 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), "MyDirectory");
// 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("MyDirectory", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).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;
}
}
我正在主活动屏幕上的按钮上调用 CameraActivity 。
答案 0 :(得分：2)
当我拍照并且onPictureTaken（）被调用时出现问题：它要么不起作用，要么花费很长时间来保存照片
这是一个大文件，您正在主应用程序线程上写一个文件。
基本上，我只想访问原始字节数组，而不必保存它
然后不要保存它。 小心使用静态数据成员将字节数组放在主活动可以使用的地方（当你完成它时，null输出静态引用，所以内存可以是垃圾收集）。
答案 1 :(得分：1)
如果您open the camera on a secondary event thread，将在该主题上调用您的pictureTaken()回调，而不会阻碍UI响应。请注意，您仍然可以从camera.takePicture()调用onClick()，即从UI线程调用。{/ p>
这仍然不是一个银弹：你可能想要将文件卸载到另一个工作线程，让相机拍下一张照片。正如上面所写的Mark，如果您只需要实时访问原始字节数组，请不要写入文件。