3
我有一個應用程序可以通過底部的完整代碼拍攝照片。我的問題是關於如何訪問存儲在jpeg中的縮略圖或生成新的縮略圖。將代碼放在這個類中，或者是一個單獨的類，它根據事件或時間表檢查文件夾並生成縮略圖沒有問題。在Android中拍攝照片後保存縮略圖
具體來說，我已經設置了那裏有一個縮略圖，但無論如何無法訪問它。我嘗試過實施ExifInterface，並嘗試手動調整照片大小。我能夠將其他參數放入Jpeg Exif（將一些隨機數字放入經度和緯度）。查看文件確認數據已寫入。非常感謝。
public void surfaceChanged(SurfaceHolder holder,int format, int width, int height) {
Camera.Parameters parameters=camera.getParameters();
parameters.setPreviewSize(width, height);
parameters.setPictureFormat(PixelFormat.JPEG);
parameters.setJpegThumbnailQuality(50);
parameters.setJpegThumbnailSize(192, 256);
camera.setParameters(parameters);
camera.startPreview();
}
這是我嘗試和使用將Exif接口失敗：
ExifInterface myEI = new ExifInterface(photo.getPath());
byte[] thumbArray = myEI.getThumbnail();
File thumbFolder = new File(appFolder.getPath(), "thumbnails");
if (!thumbFolder.exists())
{
thumbFolder.mkdirs();
}
File thumbnail=new File(thumbFolder, picFile.getName());
if (thumbnail.exists()) {
thumbnail.delete();
}
Bitmap bitmap = BitmapFactory.decodeByteArray(thumbArray, 0, thumbArray.length);
FileOutputStream fos = openFileOutput(thumbnail.getPath(), MODE_WORLD_READABLE);
bitmap.compress(CompressFormat.JPEG, 50, fos);
fos.close();
類的全部代碼。
public class PictureTaker extends Activity {
private static final String TAG = "PictureTaker";
private SurfaceView preview=null;
private SurfaceHolder previewHolder=null;
private Camera camera=null;
String filename;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.camera);
preview=(SurfaceView)findViewById(R.id.preview);
previewHolder=preview.getHolder();
previewHolder.addCallback(surfaceCallback);
previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode==82 || keyCode==KeyEvent.KEYCODE_SEARCH) {
takePicture();
return(true);
}
return super.onKeyDown(keyCode, event);
}
private void exitCamera() {
finish();
super.onStop();
}
private void takePicture() {
camera.takePicture(null, null, photoCallback);
}
SurfaceHolder.Callback surfaceCallback=new SurfaceHolder.Callback() {
public void surfaceCreated(SurfaceHolder holder) {
camera=Camera.open();
try {
camera.setPreviewDisplay(previewHolder);
}
catch (Throwable t) {
Log.d(TAG, "Exception in setPreviewDisplay()", t);
}
}
public void surfaceChanged(SurfaceHolder holder,int format, int width, int height) {
Camera.Parameters parameters=camera.getParameters();
parameters.setPreviewSize(width, height);
parameters.setPictureFormat(PixelFormat.JPEG);
parameters.setJpegThumbnailQuality(50);
parameters.setJpegThumbnailSize(192, 256);
camera.setParameters(parameters);
camera.startPreview();
}
public void surfaceDestroyed(SurfaceHolder holder) {
camera.stopPreview();
camera.release();
camera=null;
}
};
Camera.PictureCallback photoCallback=new Camera.PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
new SavePhotoTask().execute(data);
camera.startPreview();
}
};
class SavePhotoTask extends AsyncTask<byte[], String, String> {
@Override
protected String doInBackground(byte[]... jpeg) {
filename = Utilities.getTimeString() + ".jpg";
File photo=new File(filename);
if (photo.exists()) {
photo.delete();
}
try {
FileOutputStream fos=new FileOutputStream(photo.getPath());
fos.write(jpeg[0]);
fos.close();
}
catch (java.io.IOException e) {
Log.d(TAG, "Exception in photoCallback", e);
}
return(null);
}
}
}