Question

新手求教.有关onPreviewFrame未被调用的问题

Answer 1

在写一个简单的通过onPreviewFrame获取摄像头当前预览的图像再发送出去的程序。
但是运行的时候发现完全就没有调用这个函数。
用debug逐步调试的时候发现走到
camera.setPreviewCallback(MainActivity.this);这句就直接跳到设置变量的Camera camera;这句话然后就没有了。。。完全没有调用onPreviewFrame这个函数
代码

Java code?
package com.example.testfordraw;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import javax.security.auth.callback.Callback;
import android.app.Activity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.YuvImage;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.util.AttributeSet;
import android.view.Menu;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends Activity implements SurfaceHolder.Callback,Camera.PreviewCallback{
private Camera camera;
public static ByteArrayOutputStream outputstream = null;
private SurfaceView msurfaceview;
private Button buttonstart;
private Button buttonstop;
private MediaRecorder recorder;
private SurfaceHolder surfaceholder;
private File savefile;
private File SDfile;
private String savepath;
private File recfile;
private int Width = 320;
private int Height = 240;
private boolean isRecording = false ;
private boolean istrans = false ;
private int videoformat=0;
private int VideoQuality=85;
private float VideoWidthRatio=1;
private float VideoHeightRatio=1;
private String username= "wh";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
getWindow().setFormat(PixelFormat.TRANSLUCENT);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
setContentView(R.layout.activity_main);
msurfaceview = (SurfaceView) findViewById(R.id.mysurfaceview);
buttonstart = (Button) findViewById(R.id.start);
SDfile = Environment.getExternalStorageDirectory();
savepath = SDfile.getAbsolutePath()+File.separator+"mvideo"+File.separator;
savefile = new File(savepath);
buttonstart.setText("start");
buttonstart.setOnClickListener(new buttonstartlistener());
if (!savefile.exists())
{
savefile.mkdirs();
}
}
class buttonstartlistener implements OnClickListener{

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(istrans==false)
{
//record();
istrans = true;
camera.setPreviewCallback(MainActivity.this);
}else{
//Stoprecording();
istrans =false;
}
if(istrans == false)
{
buttonstart.setText("start");
}else{
buttonstart.setText("stop");
}
}
}
public void Stoprecording() {
if(recorder!= null){
recorder.stop();
recorder.reset();
recorder.release();
recorder = null;
isRecording = false ;
}
try{
camera.reconnect();
}catch(IOException e ){
Toast.makeText(this, "reconect fail", 0).show();
e.printStackTrace();
}
}
public void record()
{
try{

camera.unlock();
isRecording = true ;
recorder = new MediaRecorder();
recfile = File.createTempFile("Video",".3gp",savefile);
recorder.setCamera(camera);
recorder.reset();
recorder.setCamera(camera);
recorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
recorder.setOutputFile(recfile.getAbsolutePath());
recorder.setVideoSize(320,480);
recorder.setVideoFrameRate(20);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setPreviewDisplay(surfaceholder.getSurface());
recorder.prepare();
recorder.start();
}catch(IOException e){
e.printStackTrace();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
// TODO Auto-generated method stub
if(istrans == false){
return;
}
if(data!=null)
{
try{
YuvImage image = new YuvImage(data, videoformat, Width, Height, null);
if(image!=null){
ByteArrayOutputStream outstream = new ByteArrayOutputStream();
Rect rect = new Rect(0,0,(int)(VideoWidthRatio*Width),(int)(VideoHeightRatio*Height));
image.compressToJpeg(rect, VideoQuality, outstream);
outputstream = outstream;
outstream.flush();
}
}catch(Exception e){}
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
if(camera != null){
return;
}
camera.stopPreview();
camera.setPreviewCallback(MainActivity.this);

Camera.Parameters parameters = camera.getParameters();
Size size = parameters.getPreviewSize();
Width = size.width;
Height = size.height;
videoformat = parameters.getPreviewFormat();
camera.startPreview();
// TODO Auto-generated method stub

}

@Override
protected void onStart() {
// TODO Auto-generated method stub
surfaceholder = msurfaceview.getHolder();
surfaceholder.addCallback(this);
surfaceholder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
VideoWidthRatio=VideoWidthRatio/100f;
VideoHeightRatio=VideoHeightRatio/100f;
super.onStart();
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
camera = Camera.open();
try{
camera.setPreviewDisplay(surfaceholder);
}catch (IOException e){
e.printStackTrace();
}
camera.startPreview();
Camera.Parameters parameters = camera.getParameters();
Size size = parameters.getPreviewSize();
Width = size.width;
Height = size.height;
videoformat = parameters.getPreviewFormat();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
if(camera !=null){
camera.setPreviewCallback(null);
camera.stopPreview();
camera.release();
camera = null;
}
}
}