androidcamera(4)

先说说我的测试机器&＃xff1a;nexus s。以下的结果都是通过nexus s上测试通过。

这次先说说步骤&＃xff1a;下载zxing2.0&＃xff0c;里面的core有个core.jar这个有用&＃xff0c;将它引用到你的工程下。接着在目录android\src\com\google\zxing\client\android\PlanarYUVLuminanceSource.java&＃xff0c;将它复制到你的工程的src文件夹下&＃xff0c;记得改了它的包名。准备工作就完成了。然后就上代码&＃xff1a;

package com.TestCamera2;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.Result;
import com.TestCamera2.PlanarYUVLuminanceSource;
import com.google.zxing.common.HybridBinarizer;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ImageFormat;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.YuvImage;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.Display;
import android.view.KeyEvent;
import android.view.SurfaceHolder;
import android.view.View;
import android.view.SurfaceHolder.Callback;
import android.view.View.OnClickListener;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
public class TestCamera2Activity extends Activity {private Camera camera;private SurfaceView surfaceView;private boolean preview;final static int width &＃61; 352; final static int height &＃61; 288; int dstLeft, dstTop, dstWidth, dstHeight; private Timer mTimer;private MyTimerTask mTimerTask ;private Button btn;private Camera.PreviewCallback previewCallback;&＃64;Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);requestWindowFeature(Window.FEATURE_NO_TITLE);setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);Window window &＃61; getWindow();window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);setContentView(R.layout.main);surfaceView &＃61; (SurfaceView) findViewById(R.id.preview_view);surfaceView.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);surfaceView.getHolder().setFixedSize(352, 288); //设定surface的大小&＃xff0c;必须要&＃xff0c;除非你的surface刚好是你手机preview允许的大小 surfaceView.getHolder().addCallback(new SurfaceViewCallback());btn&＃61;(Button)findViewById(R.id.button1);btn.setOnClickListener(new OnClickListener(){public void onClick(View v) {mTimer &＃61; new Timer(); mTimerTask &＃61; new MyTimerTask(); mTimer.schedule(mTimerTask, 0, 80);}});previewCallback &＃61; new Camera.PreviewCallback() {public void onPreviewFrame(byte[] data, Camera arg1) {if(data!&＃61;null){Log.i("data", "ok");if (dstLeft &＃61;&＃61; 0) {// 只赋值一次 dstLeft &＃61; surfaceView.getLeft() * width / getWindowManager().getDefaultDisplay().getWidth(); dstTop &＃61; surfaceView.getTop() * height / getWindowManager().getDefaultDisplay().getHeight(); dstWidth &＃61; (surfaceView.getRight() - surfaceView.getLeft()) * width / getWindowManager().getDefaultDisplay().getWidth(); dstHeight &＃61; (surfaceView.getBottom() - surfaceView.getTop()) * height / getWindowManager().getDefaultDisplay().getHeight(); } //PlanarYUVLuminanceSource source &＃61; new PlanarYUVLuminanceSource(data, width, height, dstLeft, dstTop, dstWidth, dstHeight,false); // 取得灰度图 Bitmap bm &＃61; source.renderCroppedGreyscaleBitmap(); // 保存灰度图 String picDirStr &＃61; Environment.getExternalStorageDirectory()&＃43;"/"; File picDir &＃61; new File(picDirStr); if(!picDir.exists()){ picDir.mkdir(); } String picName &＃61; picDirStr &＃43; System.currentTimeMillis() &＃43; ".jpg"; File myCaptureFile &＃61; new File(picName); try { BufferedOutputStream bos &＃61; new BufferedOutputStream( new FileOutputStream(myCaptureFile)); bm.compress(Bitmap.CompressFormat.JPEG, 80, bos); bos.flush(); bos.close(); camera.startPreview(); Log.i("pic","ok");} catch (Exception e) { e.printStackTrace();}// BinaryBitmap bitmap &＃61; new BinaryBitmap(new HybridBinarizer(source)); MultiFormatReader reader &＃61; new MultiFormatReader(); try { Result result &＃61; reader.decode(bitmap); String strResult &＃61; "BarcodeFormat:"&＃43; result.getBarcodeFormat().toString() &＃43; " text:"&＃43; result.getText(); Log.i("result",strResult);Toast.makeText(getApplicationContext(), strResult, Toast.LENGTH_LONG&＃43;2000).show();mTimer.cancel(); } catch (Exception e) { Log.i("result","faile");} }else{Log.i("data", "null");}} };}private final class SurfaceViewCallback implements SurfaceHolder.Callback {public void surfaceCreated(SurfaceHolder holder) {camera &＃61; Camera.open(); }public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {Camera.Parameters parameters &＃61; camera.getParameters();parameters.setPreviewSize(width, height); parameters.setPreviewFrameRate(5); parameters.setPictureFormat(PixelFormat.JPEG); parameters.set("jpeg-quality", 85);camera.setParameters(parameters); try{ camera.setPreviewDisplay(holder);preview &＃61; true;Log.i("camera", "camera open!");}catch(IOException exception) { camera.release(); camera &＃61; null; } camera.startPreview();Log.i("camera","camera preview");}public void surfaceDestroyed(SurfaceHolder holder) {if (camera !&＃61; null) { if(preview) {camera.stopPreview();preview &＃61; false;Log.i("destroyprevie", "ok!");} camera.release();camera &＃61; null;}} }class MyTimerTask extends TimerTask { &＃64;Override public void run() { camera.autoFocus(new Camera.AutoFocusCallback() {public void onAutoFocus(boolean success, Camera camera) {if(success){Log.i("focus","ok!");camera.setOneShotPreviewCallback(previewCallback);}}}); }}
}


接着解说一下这个过程&＃xff1a;你按button&＃xff0c;手机就开始自动对焦&＃xff08;由Timer不断触发&＃xff09;&＃xff0c;当对焦成功时&＃xff0c;调用函数onPreviewFrame来取得那一帧的图片data然后生成对象PlanarYUVLuminanceSource&＃xff0c;由这个对象返回一张灰度图&＃xff0c;我将它保存下来以便观察。接下来的工作就是交给解码器完成工作了&＃xff0c;若解码成功则直接输出解码结果&＃xff0c;然后。如果解码不成功&＃xff0c;会不断对焦&＃xff0c;不断进行尝试。大家可能觉得这个过程十分简单&＃xff0c;但是对于这只菜鸟要用一个星期的时间&＃xff0c;花时间搞懂照相机&＃xff0c;花时间上网找资料&＃xff0c;表示看了很多资料http://www.cnblogs.com/liuan/category/347622.html&＃xff08;我从这个博客学到很多&＃xff0c;要感谢一下这个博客的博主&＃xff09;&＃xff0c;花时间看看zxing&＃xff0c;然后慢慢学习。这个过程也学习到很多东西。

最后我说说我这个demo的问题。首先看看我的布局文件



android:screenOrientation&＃61;"landscape" />



这样的布局导致不能知道surfaceview的大小&＃xff0c;但是surfaceview比较大&＃xff0c;所以必须要设定
surfaceView.getHolder().setFixedSize(352, 288);我还操蛋的发现parameters.setPreviewSize(width, height); 根本不起作用的&＃xff0c;所以还是不设定好&＃xff0c;直接设定surfaceview。然后我将surfaceview设定成352*288&＃xff0c;这个surfaceview就太小了而且所得到的灰度图大概只能surfaceview的一半大&＃xff0c;所以解码永远不成功的&＃xff0c;于是我去看了类
PlanarYUVLuminanceSource的构造函数&＃xff0c;但是不知所云。我猜想&＃xff0c;因为源程序是满屏幕只取中间那个很小的view的灰度图&＃xff0c;所以我的小surfaceview被活生生的截图了&＃xff08;本来就刚刚好找到条形码&＃xff09;&＃xff0c;所以解码不成功。更多发现留给大家了。所以我直接将surfaceview放得大大好了。

接下来我的android camera系列就结束了&＃xff08;我留给自己的工作是实现跟源程序一样的界面&＃xff09;。这次让我感慨良多。这个是我第一次写这样的文章&＃xff0c;发觉是超级难写。因为你要尽量保证你的准确性还要描述清楚&＃xff08;我知道我的表达能力十分有限&＃xff09;&＃xff0c;那么就不得不做大量的尝试&＃xff0c;查看大量的资料&＃xff08;我花了一个多星期吧&＃xff0c;才开始接触android两个星期左右&＃xff09;。

附上demo&＃xff1a;android camera&＃xff08;4&＃xff09;

警告&＃xff1a;android camera系列的文章是由一个刚接触android不到一个月的菜鸟所写&＃xff0c;所以必然存在很多错误&＃xff0c;请大家指出