I am developing an android camera app, using autofocus.
The issue, i am able to capture for the first time, but when i am trying to capture for the second time the below exception occurs.
4-19 11:28:32.509: E/AndroidRuntime(4409): FATAL EXCEPTION: main
04-19 11:28:32.509: E/AndroidRuntime(4409): java.lang.RuntimeException: takePicture failed
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.hardware.Camera.native_takePicture(Native Method)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.hardware.Camera.takePicture(Camera.java:878)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.hardware.Camera.takePicture(Camera.java:842)
04-19 11:28:32.509: E/AndroidRuntime(4409): at com.example.camerasample.MainActivity$4.onClick(MainActivity.java:60)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.view.View.performClick(View.java:2485)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.view.View$PerformClick.run(View.java:9080)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.os.Handler.handleCallback(Handler.java:587)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.os.Handler.dispatchMessage(Handler.java:92)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.os.Looper.loop(Looper.java:130)
04-19 11:28:32.509: E/AndroidRuntime(4409): at android.app.ActivityThread.main(ActivityThread.java:3687)
04-19 11:28:32.509: E/AndroidRuntime(4409): at java.lang.reflect.Method.invokeNative(Native Method)
04-19 11:28:32.509: E/AndroidRuntime(4409): at java.lang.reflect.Method.invoke(Method.java:507)
04-19 11:28:32.509: E/AndroidRuntime(4409): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
04-19 11:28:32.509: E/AndroidRuntime(4409): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
04-19 11:28:32.509: E/AndroidRuntime(4409): at dalvik.system.NativeStart.main(Native Method)
But works fine while capturig in a camera without autofocus functionality.
Below i have attached my codes
MainActivity.java
package com.example.camerasample;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import com.example.camerasample.R;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnLongClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.FrameLayout;
public class MainActivity extends Activity {
private static final String TAG = "CamTestActivity";
Preview preview;
Button buttonClick;
Camera camera;
String fileName;
Activity act;
Context ctx;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ctx = this;
act = this;
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
preview = new Preview(this, (SurfaceView)findViewById(R.id.surfaceView));
preview.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
((FrameLayout) findViewById(R.id.preview)).addView(preview);
preview.setKeepScreenOn(true);
buttonClick = (Button) findViewById(R.id.buttonClick);
buttonClick.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
camera.takePicture(shutterCallback, rawCallback, jpegCallback);
}
});
buttonClick.setOnLongClickListener(new OnLongClickListener(){
@Override
public boolean onLongClick(View arg0) {
camera.autoFocus(new AutoFocusCallback(){
@Override
public void onAutoFocus(boolean arg0, Camera arg1) {
}
});
return true;
}
});
}
@Override
protected void onResume() {
super.onResume();
camera = Camera.open();
camera.startPreview();
preview.setCamera(camera);
}
@Override
protected void onPause() {
if(camera != null) {
camera.stopPreview();
preview.setCamera(null);
camera.release();
camera = null;
}
super.onPause();
}
private void resetCam() {
camera.startPreview();
preview.setCamera(camera);
}
ShutterCallback shutterCallback = new ShutterCallback() {
public void onShutter() {
// Log.d(TAG, "onShutter'd");
}
};
PictureCallback rawCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
// Log.d(TAG, "onPictureTaken - raw");
}
};
PictureCallback jpegCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
FileOutputStream outStream = null;
try {
// Write to SD Card
fileName = String.format("/sdcard/camtest/%d.jpg", System.currentTimeMillis());
outStream = new FileOutputStream(fileName);
outStream.write(data);
outStream.close();
Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length);
resetCam();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
}
Log.d(TAG, "onPictureTaken - jpeg");
}
};
}
Preview.java
package com.example.camerasample;
import java.io.IOException;
import java.util.List;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
class Preview extends ViewGroup implements SurfaceHolder.Callback {
private final String TAG = "Preview";
SurfaceView mSurfaceView;
SurfaceHolder mHolder;
Size mPreviewSize;
List<Size> mSupportedPreviewSizes;
Camera mCamera;
@SuppressWarnings("deprecation")
Preview(Context context, SurfaceView sv) {
super(context);
mSurfaceView = sv;
mHolder = mSurfaceView.getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void setCamera(Camera camera) {
mCamera = camera;
if (mCamera != null) {
mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
requestLayout();
// get Camera parameters
Camera.Parameters params = mCamera.getParameters();
List<String> focusModes = params.getSupportedFocusModes();
if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
// set the focus mode
params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
// set Camera parameters
mCamera.setParameters(params);
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// We purposely disregard child measurements because act as a
// wrapper to a SurfaceView that centers the camera preview instead
// of stretching it.
final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
setMeasuredDimension(width, height);
if (mSupportedPreviewSizes != null) {
mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (changed && getChildCount() > 0) {
final View child = getChildAt(0);
final int width = r - l;
final int height = b - t;
int previewWidth = width;
int previewHeight = height;
if (mPreviewSize != null) {
previewWidth = mPreviewSize.width;
previewHeight = mPreviewSize.height;
}
// Center the child SurfaceView within the parent.
if (width * previewHeight > height * previewWidth) {
final int scaledChildWidth = previewWidth * height / previewHeight;
child.layout((width - scaledChildWidth) / 2, 0,
(width + scaledChildWidth) / 2, height);
} else {
final int scaledChildHeight = previewHeight * width / previewWidth;
child.layout(0, (height - scaledChildHeight) / 2,
width, (height + scaledChildHeight) / 2);
}
}
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where
// to draw.
try {
if (mCamera != null) {
mCamera.setPreviewDisplay(holder);
}
} catch (IOException exception) {
Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
if (mCamera != null) {
mCamera.stopPreview();
}
}
private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.1;
double targetRatio = (double) w / h;
if (sizes == null) return null;
Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
// Try to find an size match aspect ratio and size
for (Size size : sizes) {
double ratio = (double) size.width / size.height;
if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
// Cannot find the one match the aspect ratio, ignore the requirement
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Size size : sizes) {
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
return optimalSize;
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
if(mCamera != null) {
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
requestLayout();
mCamera.setParameters(parameters);
mCamera.startPreview();
}
}
}
Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.camerasample"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" />
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".MainActivity"
android:screenOrientation="landscape" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
I couldnt find exact solution anywhere, please help.
I propose two solutions that worked for me. 1) Stop and Resume the camera correctly. I do it by calling these methods on onPause and onResume, also in the middle of the camera Preview, where I scan QR codes in my app:
public void stopCamera(){
mCamera.cancelAutoFocus();
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
mPreviewing = false;
}
public void rethrottleCamera(){
updateViews(); //Updates my Layouts
mPreviewing = true;
mCamera.startPreview();
mCamera.setPreviewCallback(previewCb);
mCamera.autoFocus(autoFocusCB);
}
2)Very tricky but worked like magic! Make sure that you call autofocus AFTER the preview surface has been created. To do this run Autofocus with a 200ms delay, to buy time for the surface to be created. Set this by pressing ctrl+clic over a "CameraPreview" object declaration, such as:
CameraPreview my_camera;
Look for the "public void surfaceChanged" method and make this changes:
//Add a delay to AUTOFOCUS after mCamera.startpreview();!!:
mCamera.startPreview();
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
mCamera.autoFocus(autoFocusCallback);
}
}, 200); //<-200 millisecond delay
//If you call autofocus right after startPreview, chances are,
//that the previewSurface will have not been created yet,
//and autofocus will fail:
mCamera.startPreview(); //Bad idea!
mCamera.autoFocus(autoFocusCallback); //Bad idea!
There are plenty other fixes, but these two may save your day.
Yes, the code crashes when you autofocus on the camera twice. You can workaround this issue, by having a flag, which will check if the autofocus has started, and then skip the execution of the autofocus again.
来源：https://stackoverflow.com/questions/16098474/takepicture-failed-after-autofocus-for-the-second-time