Android下摄像头预览数据
由于Android下摄像头预览数据只能 ImageFormat.NV21 格式的，所以解码时要经过一翻周折.
Camera mCamera = Camera.open(); Camera.Parameters p = mCamera.getParameters(); p.setPreviewFormat(ImageFormat.NV21); /*这是唯一值，也可以不设置。有些同学可能设置成 PixelFormat 下面的一个值，其实是不对的，具体的可以看官方文档*/
mCamera.setParameters(p);
mCamera.startPreview();
下面是解码核心部分：
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
Size size = camera.getParameters().getPreviewSize();
try{
YuvImage image = new YuvImage(data, ImageFormat.NV21, size.width, size.height, null);
if(image!=null){
ByteArrayOutputStream stream = new ByteArrayOutputStream();
image.compressToJpeg(new Rect(0, 0, size.width, size.height), 80, stream);
Bitmap bmp = BitmapFactory.decodeByteArray(stream.toByteArray(), 0, stream.size());
stream.close();
}
}catch(Exception ex){
Log.e("Sys","Error:"+ex.getMessage());
}
}
代码很简单。就是把YUV数据转成 Bitmap 就行了，系统提供 YuvImage 类。
package com.example.surface1;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import android.app.Activity;
/* 延含学习 */
//import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
/* 引用Camera类 */
import android.hardware.Camera;
/* 引用PictureCallback为取得拍照后的事件 */
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
/**
* 使Activity实现SurfaceHolder.Callback
* @author K1311P99
*
*/
public class MainActivity extends Activity implements SurfaceHolder.Callback {
@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;
}
/* 建立私有Camera对象 */
private Camera mCamera01;
private Button mButton01, mButton02, mButton03;
/* 当成review照下来的相片之用 */
private ImageView mImageView01;
private TextView mTextView01;
private static String TAG = "HIPPO_DEBUG";
private SurfaceView mSurfaceView01;
private SurfaceHolder mSurfaceHolder01;
//private int intScreenX, intScreenY;
/* 默认相机预览模式为false */
private boolean bIfPreview = false;
/* 将照下来的图片保存在此 */
private String strCaptureFilePath = "/sdcard/camera_snap.jpg";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
/* 使应用程序全屏运行，不使用title bar */
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
/* 判断存储卡是否存在 */
if(!checkSDCard())
{
/* 提醒User未安装存储卡 */
mMakeTextToast
(
getResources().getText(R.string.str_err_nosd).toString(),
true
);
}
/* 取得屏幕解析像素 */
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
//intScreenX = dm.widthPixels;
//intScreenY = dm.heightPixels;
//Log.i(TAG, Integer.toString(intScreenX));
/* 延含学习 */
//import android.content.pm.ActivityInfo;
//this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
mTextView01 = (TextView) findViewById(R.id.myTextView1);
mImageView01 = (ImageView) findViewById(R.id.myImageView1);
/* 以SurfaceView作为相机Preview之用 */
mSurfaceView01 = (SurfaceView) findViewById(R.id.mSurfaceView1);
/* 绑定SurfaceView，取得SurfaceHolder对象 */
mSurfaceHolder01 = mSurfaceView01.getHolder();
/* Activity必须实现SurfaceHolder.Callback */
mSurfaceHolder01.addCallback(MainActivity.this);
/* 额外的设置预览大小设定，在此不使用 */
//mSurfaceHolder01.setFixedSize(320, 240);
/*
* 以SURFACE_TYPE_PUSH_BUFFERS(3)
* 作为SurfaceHolder显示类型
* */
mSurfaceHolder01.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
mButton01 = (Button)findViewById(R.id.myButton1);
mButton02 = (Button)findViewById(R.id.myButton2);
mButton03 = (Button)findViewById(R.id.myButton3);
/* 开启相机及Preview */
mButton01.setOnClickListener(new Button.OnClickListener()
{
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
/* 自定义初始化开启相机函数 */
initCamera();
}
});
/* 停止Preview及相机 */
mButton02.setOnClickListener(new Button.OnClickListener()
{
@Override
public void onClick(View arg0)
{
// TODO Auto-generated method stub
/* 自定义重置相机，并关闭相机预览函数 */
resetCamera();
}
});
/* 拍照 */
mButton03.setOnClickListener(new Button.OnClickListener()
{
@Override
public void onClick(View arg0)
{
// TODO Auto-generated method stub
/* 当存储卡存在才允许拍照，保存临时图像文件 */
if(checkSDCard())
{
/* 自定义拍照函数 */
takePicture();
}
else
{
/* 存储卡不存在的显示提示 */
mTextView01.setText
(
getResources().getText(R.string.str_err_nosd).toString()
);
}
}
});
}
/* 告订初始相机函数 */
private void initCamera()
{
if(!bIfPreview)
{
/* 若相机非?预览模式，则开启相机 */
try
{
/*
* The Heap 是应用程序?手机里执行所配置的空间
* 当超过预设的16 MB（每几个应用程序）时就会导致 "Out of memory"的错误
* 目前看来是Cupcake(AVD 1.5)?会发生
* Connect E from ICameraClient 0x....
* new client (0x...) sttempting to connect - rejected
* */
mCamera01 = Camera.open();
}
catch(Exception e)
{
Log.e(TAG, e.getMessage());
}
}
if (mCamera01 != null && !bIfPreview)
{
try
{
Log.i(TAG, "inside the camera");
mCamera01.setPreviewDisplay(mSurfaceHolder01);
/* 建立Camera.Parameters对象 */
Camera.Parameters parameters = mCamera01.getParameters();
/* 设定相片格式为JPEG */
parameters.setPictureFormat(PixelFormat.JPEG);
//parameters.setPreviewSize(w, h);
List<Camera.Size> s=parameters.getSupportedPreviewSizes();
try
{
if(s!=null)
{
for(int i=0;i<s.size();i++)
{
Log.i(TAG,""+(((Camera.Size)s.get(i)).height)+"/"+(((Camera.Size)s.get(i)).width));
}
}
parameters.setPreviewSize(320, 240);
//parameters.setPreviewSize(176, 144);
/* ?2.0模拟器中，设置不支持的PreviewSize将造成Exception */
s=parameters.getSupportedPictureSizes();
try
{
if(s!=null)
{
for(int i=0;i<s.size();i++)
{
Log.i(TAG,""+(((Camera.Size)s.get(i)).height)+"/"+(((Camera.Size)s.get(i)).width));
}
}
/* ?2.0模拟器中，设置不支持的PictureSize将造成Exception */
parameters.setPictureSize(512, 384);
//parameters.setPictureSize(213, 350);
/* 将Camera.Parameters设定予Camera */
mCamera01.setParameters(parameters);
/* setPreviewDisplay唯几的参数为SurfaceHolder */
mCamera01.setPreviewDisplay(mSurfaceHolder01);
/* 立即运行Preview */
mCamera01.startPreview();
bIfPreview = true;
Log.i(TAG, "startPreview");
}
catch (Exception e)
{
Log.i(TAG, e.toString());
e.printStackTrace();
}
}
catch (Exception e)
{
Toast.makeText
(
MainActivity.this,
"initCamera error.",
Toast.LENGTH_LONG
).show();
e.printStackTrace();
}
}
catch (IOException e)
{
// TODO Auto-generated catch block
mCamera01.release();
mCamera01 = null;
Log.i(TAG, e.toString());
e.printStackTrace();
}
}
}
/* 拍照撷取影像 */
private void takePicture()
{
if (mCamera01 != null && bIfPreview)
{
/* 调用takePicture()方法拍照 */
mCamera01.takePicture(shutterCallback, rawCallback, jpegCallback);
}
}
/* 相机重置 */
private void resetCamera()
{
if (mCamera01 != null && bIfPreview)
{
mCamera01.stopPreview();
/* 延含学习，释放Camera对象 */
//mCamera01.release();
//mCamera01 = null;
Log.i(TAG, "stopPreview");
bIfPreview = false;
}
}
private ShutterCallback shutterCallback = new ShutterCallback()
{
public void onShutter()
{
// Shutter has closed
}
};
private PictureCallback rawCallback = new PictureCallback()
{
public void onPictureTaken(byte[] _data, Camera _camera)
{
// TODO Handle RAW image data
}
};
private PictureCallback jpegCallback = new PictureCallback()
{
public void onPictureTaken(byte[] _data, Camera _camera)
{
// TODO Handle JPEG image data
/* onPictureTaken传入的第几个参数即为相片的byte */
Bitmap bm = BitmapFactory.decodeByteArray(_data, 0, _data.length);
/* 创建文件 */
File myCaptureFile = new File(strCaptureFilePath);
try
{
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile));
/* 采用压缩转档方法 */
bm.compress(Bitmap.CompressFormat.JPEG, 80, bos);
/* 调用flush()方法，更新BufferStream */
bos.flush();
/* 结束OutputStream */
bos.close();
/* 将拍照下来且保存完毕的图文件，显示出来 */
mImageView01.setImageBitmap(bm);
/* 显示完图片，立即重置相机，并关闭预览 */
resetCamera();
/* 再重新启动相机继续预览 */
initCamera();
}
catch (Exception e)
{
Log.e(TAG, e.getMessage());
Log.e(TAG, e.toString());
}
}
};
/* 自定义文件函数 */
private void delFile(String strFileName)
{
try
{
File myFile = new File(strFileName);
if(myFile.exists())
{
myFile.delete();
}
}
catch (Exception e)
{
Log.e(TAG, e.toString());
e.printStackTrace();
}
}
public void mMakeTextToast(String str, boolean isLong)
{
if(isLong==true)
{
Toast.makeText(MainActivity.this, str, Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(MainActivity.this, str, Toast.LENGTH_SHORT).show();
}
}
private boolean checkSDCard()
{
/* 判断存储卡是否存在 */
if(android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
{
return true;
}
else
{
return false;
}
}
@Override
public void surfaceChanged(SurfaceHolder surfaceholder, int format, int w, int h)
{
// TODO Auto-generated method stub
Log.i(TAG, "Surface Changed1");
}
@Override
public void surfaceCreated(SurfaceHolder surfaceholder)
{
// TODO Auto-generated method stub
Log.i(TAG, "Surface Changed2");
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceholder)
{
// TODO Auto-generated method stub
/* 当Surface不存在，就需要删除图片 */
try
{
delFile(strCaptureFilePath);
mCamera01.stopPreview();
mCamera01.release();
mCamera01 = null;
Log.i(TAG, "Surface Destroyed");
}
catch(Exception e)
{
e.printStackTrace();
}
}
@Override
protected void onPause()
{
// TODO Auto-generated method stub
try
{
resetCamera();
mCamera01.release();
}
catch(Exception e)
{
e.printStackTrace();
}
super.onPause();
}
}