每5秒钟在android中拍照 [英] Taking pictures in android every 5 seconds
问题描述
使用相机API，我能够成功拍摄照片并将其保存到文件夹中.这是我正在使用的代码:
Using the camera API, i am able to successfully take a picture and save it to a folder. Here is the code that i am using:
Main.xml:
<FrameLayout
android:id="@+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1" />
<Button
android:id="@+id/button_capture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Capture" />
助手类:
import java.io.IOException;
import android.content.Context;
import android.hardware.Camera;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class CameraPreview extends SurfaceView implements
SurfaceHolder.Callback {
private SurfaceHolder mSurfaceHolder;
private Camera mCamera;
// Constructor that obtains context and camera
@SuppressWarnings("deprecation")
public CameraPreview(Context context, Camera camera) {
super(context);
this.mCamera = camera;
this.mSurfaceHolder = this.getHolder();
this.mSurfaceHolder.addCallback(this);
this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
try {
mCamera.setPreviewDisplay(surfaceHolder);
mCamera.setDisplayOrientation(90);
mCamera.startPreview();
} catch (IOException e) {
// left blank for now
}
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
mCamera.stopPreview();
mCamera.release();
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int format,
int width, int height) {
// start preview with new settings
try {
mCamera.setPreviewDisplay(surfaceHolder);
mCamera.startPreview();
} catch (Exception e) {
// intentionally left blank for a test
}
}
}
活动类别:
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
public class MyCamera extends Activity {
private Camera mCamera;
private CameraPreview mCameraPreview;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mCamera = getCameraInstance();
mCameraPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mCameraPreview);
Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mCamera.takePicture(null, null, mPicture);
}
});
}
/**
* Helper method to access the camera returns null if it cannot get the
* camera or does not exist
*
* @return
*/
private Camera getCameraInstance() {
Camera camera = null;
try {
camera = Camera.open();
} catch (Exception e) {
// cannot get camera or does not exist
}
return camera;
}
PictureCallback mPicture = new PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile();
if (pictureFile == null) {
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
} catch (IOException e) {
}
}
};
private static File getOutputMediaFile() {
File mediaStorageDir = new File(
Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
"MyCameraApp");
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;
mediaFile = new File(mediaStorageDir.getPath() + File.separator
+ "IMG_" + timeStamp + ".jpg");
return mediaFile;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.my_camera, menu);
return true;
}
}
我还向清单文件添加了以下内容:
I have also added to the manifest file the following:
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
我遇到以下问题:
我要执行以下操作:
-
按下拍摄按钮后，我希望相机使用倒数计时器每5秒自动继续拍摄一张照片.所以我添加了以下内容:
After pressing the capture button, i want the camera to automatically continue capturing pictures every 5 sec, by using a count down timer. So i have added the following :
while(true){
new CountDownTimer(5000,1000){
@Override
public void onFinish() {
mCamera.takePicture(null, null, mPicture);
}
@Override
public void onTick(long millisUntilFinished) {
}
}.start();
}
但是，我不再有照片了.我添加了while(true)，使代码没有重复.我没有使用while(true)尝试过，并且按预期，图像捕获被延迟了5秒
However, I am no longer getting a picture. I added the while(true) to make the code repeat by its not. I have tried it without the while(true) and as expected the image capturing is delayed for 5 second
第二件事是:如何更改捕获的图片的质量?
Second thing is: How can I change the quality of the captured pictures?
任何帮助将不胜感激.
推荐答案
删除while(true)，您将不需要它并创建无限的倒数计时器.
Remove the while(true), you don't need it and will create unlimited countdown timers.
将您的倒计时开始时间更改为此
Change your Countdown start to this
new CountDownTimer(5000,1000){
@Override
public void onFinish() {
}
@Override
public void onTick(long millisUntilFinished) {
mCamera.startPreview();
mCamera.takePicture(null, null, mPicture);
}
}.start();
在这种情况下，每1000毫秒调用一次
onTick，并在计时器倒数结束时调用onFinish.
onTick is called every 1000 ms in this case, and onFinish is called when the Timer countdown is finished.
如果您想每5秒重复一次，我认为CountDownTimer不能满足您的需求... Timer会更好.
If you want to repeat something every 5 seconds i don't think a CountDownTimer fits your needs... a Timer would be better.
Timer timer = new Timer();
timer.schedule(new TimerTask()
{
@Override
public void run()
{
mCamera.startPreview();
mCamera.takePicture(null, null, mPicture);
}
}, 0, 1000);
记住保存Timer实例以阻止它！
Remeber to save Timer instace to stop it!
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