Android - 无需预览即可拍照
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Android - Take picture without preview
提问by Eyal
I am trying to take a picture without preview, immediately when my application starts running and after that to save the picture in new folder - "pictures123", in the root folder. Could someone please tell me what's wrong in my code?
我正在尝试在不预览的情况下拍摄照片，当我的应用程序开始运行时立即拍照，然后将照片保存在根文件夹中的新文件夹 - “pictures123”中。有人可以告诉我我的代码有什么问题吗？
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
File directory = new File(Environment.getExternalStorageDirectory() + "/pictures123/");
if (!directory.exists()) {
directory.mkdir();
}
Camera camera = Camera.open(0);
Camera.Parameters parameters = camera.getParameters();
parameters.setPictureFormat(ImageFormat.JPEG);
camera.setParameters(parameters);
SurfaceView mview = new SurfaceView(getBaseContext());
camera.setPreviewDisplay(mview.getHolder());
camera.setPreviewDisplay(null);
camera.startPreview();
camera.takePicture(null,null,photoCallback);
camera.stopPreview();
}
Camera.PictureCallback photoCallback=new Camera.PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
try {
String root = Environment.getExternalStorageDirectory().toString();
File myDir = new File(root + "/pictures123");
File file = new File (myDir, "pic1.jpeg");
FileOutputStream out = new FileOutputStream(file);
out.write(data);
out.flush();
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e)
{
e.printStackTrace();
}
finish();
}
};
permissions:
权限：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
采纳答案by fadden
You can't take a picture without a preview, but you don't have to show the preview on screen. You can direct the output to a SurfaceTexture instead (API 11+).
您不能在没有预览的情况下拍照，但您不必在屏幕上显示预览。您可以将输出定向到 SurfaceTexture（API 11+）。
See this answerfor more details.
有关更多详细信息，请参阅此答案。
回答by hzitoun
If you are using Camera 2 API, to take picture secretly without preview or launching device's camera app you can check my project on github.
如果您使用的是Camera 2 API，要在不预览或启动设备的相机应用程序的情况下秘密拍照，您可以在 github 上查看我的项目。
回答by ashoke
I think the main problem is that you are calling takePicture immediately after startPreview which actually takes time to complete its setup. So adding a delay between those two could temporarily fix this issue, look here for more details.
我认为主要问题是您在 startPreview 之后立即调用 takePicture ，这实际上需要时间来完成其设置。因此，在这两者之间添加延迟可以暂时解决此问题，请查看此处了解更多详细信息。
回答by yushulx
It's impossible to take a picture without preview. You should read the Android online reference: http://developer.android.com/reference/android/hardware/Camera.html#takePicture.
没有预览是不可能拍照的。您应该阅读 Android 在线参考：http: //developer.android.com/reference/android/hardware/Camera.html#takePicture。
Note: This method is only valid when preview is active (after startPreview()). Preview will be stopped after the image is taken; callers must call startPreview() again if they want to re-start preview or take more pictures. This should not be called between start() and stop().
注意：此方法仅在预览处于活动状态时有效（在 startPreview() 之后）。拍摄图像后将停止预览；如果调用者想要重新开始预览或拍摄更多照片，则必须再次调用 startPreview()。这不应在 start() 和 stop() 之间调用。
