Android：扫描目录并显示图片(缩略图)(图片未存储在mediastore中)

我前一段时间做的完全相同.您必须将图像所在的文件夹名称传递给setBaseFolder.这个方法反过来调用refresh() – 使用FilenameFilter(代码不包括但很容易实现)从该文件夹获取名为orig _…. jpg的所有图像并将其保存在mFileList中.然后我们调用notifyDataSetChanged(),然后调用每个单元格的getView().

现在,在getView()中我们要么从缓存中获取一个缩略图位图,如果我们已经有了它,否则我们制作一个灰色占位符并启动ThumbnailBuilder来创建缩略图.从中获取位图.

我认为你必须稍微更改ThumbnailBuilder,因为我创建了相当大的“缩略图”(500×500),因为我还需要调整大小的图像用于其他目的.此外,当我处理相机拍摄的照片时,有一些东西,根据exif信息旋转图像.但基本上,ThumbnailBuilder只是检查是否已经有缩略图(我的缩略图图像放在同一个文件夹中,但前缀是small_而不是orig_) – 如果缩略图已经存在,我们将其作为Bitmap并完成,否则图像生成.最后,在onPostExecute()中,位图设置为ImageView.

public class Photoadapter extends BaseAdapter {

private Context mContext;
privatE int mCellSize;
private File mFolder;
private File[] mFileList;
private Map<Object,Bitmap> mThumbnails = new HashMap<Object,Bitmap>();
private Set<Object> mCreaTingtriggered = new HashSet<Object>(); // flag that creaTing already triggered

public Photoadapter(Context context,int cellSizE) {
    mContext = context;
    mCellSize = cellSize;
}

@Override
public int getCount() {
    if (mFolder == null) {
        return 0;   // don't do this
    } else {
        return mFileList.length;
    }
}

@Override
public Object getItem(int position) {
    return mFileList[position];
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position,View convertView,ViewGroup parent) {
    ImageView view = (ImageView)convertView;
    if (view == null) {
        view = new ImageView(mContext);
        view.setLayoutParams(new GridView.LayoutParams(mCellSize,mCellSizE));
        view.setScaleType(ImageView.ScaleType.CENTER_CROp);
        view.setPadding(8,8,8);
        view.setBACkgroundColor(0xFFC6CCD3);
    }
    Object item = getItem(position);
    Bitmap bm = mThumbnails.get(item);
    if (bm == null) {
        view.setImageBitmap(null);
        if (!mCreaTingtriggered.contains(item)) {
            mCreaTingtriggered.add(item);
            new ThumbnailBuilder(view,(FilE)item).execute();
        }
    } else {
        view.setImageBitmap(bm);
    }
    return view;
}

public void setBaseFolder(File baseFolder) {
    if (baseFolder == null) return;
    if (!baseFolder.equals(mFolder)) {
        releaseThumbnails();
        mFolder = baseFolder;
    }
    refresh();
}

public void refresh() {
    if (mFolder == null) {
        return;
    }
    mFileList = mFolder.listFiles(EtbApplication.origImageFilenameFilter);
    if (mFileList == null) mFileList = new File[0];
    notifyDataSetChanged();
}

public void releaseThumbnails() {
    for (Bitmap bm : mThumbnails.values()) {
        bm.recycle();
    }
    mThumbnails.clear();
}

// ------------------------------------------------------------------------------------ Asynchronous Thumbnail builder

private class ThumbnailBuilder extends AsyncTask<Void,Integer,Bitmap> {

    private ImageView mView;
    private File mFile;

    public ThumbnailBuilder(ImageView view,File filE) {
        mView = view;
        mFile = file;
    }

    @Override
    protected Bitmap doInBACkground(Void... params) {
        Log.d("adapter","make small image and thumbnail");
        try {
            return createThumbnail(mFile.getAbsolutePath());
        } catch (Exception E) {
            return null;
        }
    }

    @Override
    protected void onPostExecute(Bitmap result) {
        if (result != null) {
            mView.setImageBitmap(result);
            mThumbnails.put(mFile,result);
        } else {
            mView.setImageresource(R.drawable.ic_launcher);
        }
    }

    /**
     * Creates Thumbnail (also rotates according to exif-info)
     * @param file
     * @return
     * @throws IOException
     */
    private Bitmap createThumbnail(@R_618_10495@ng filE) throws IOException {

        File thumbnailFile = new File(file.replace("orig_","small_"));

        // If a small image version already exists,just load it and be done.
        if (thumbnailFile.exists()) {
            return BitmapFactory.decodeFile(thumbnailFile.getAbsolutePath());
        }

        // Decode image size
        BitmapFactory.options bounds = new BitmapFactory.options();
        bounds.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(file,bounds);

        if ((bounds.outWidth == -1) || (bounds.outHeight == -1))
            return null;

        int w,h;

        if (bounds.outWidth > bounds.outHeight) {   // Querformat
            w = 500;
            h = 500 * bounds.outHeight / bounds.outWidth;
        } else {    // Hochformat
            h = 500;
            w = 500 * bounds.outWidth / bounds.outHeight;
        }

        BitmapFactory.options opts = new BitmapFactory.options();
        opts.inSampleSize = 4;  // resample -- kleiner aber noch nicht die 500 Pixel,die kommen dAnn unten
        Bitmap resizedBitmap = BitmapFactory.decodeFile(file,opts);
        resizedBitmap = Bitmap.createScaledBitmap(resizedBitmap,w,h,truE);

        ExifInterface exif = new ExifInterface(filE);
        @R_618_10495@ng orient@R_618_10495@ng = exif.getAttribute(ExifInterface.TAG_ORIENTATION);
        int orientation = orient@R_618_10495@ng != null ? Integer.parseInt(orient@R_618_10495@ng) : ExifInterface.oRIENTATION_NORMAL;
        int rotationAngle = 0;
        if (orientation == ExifInterface.oRIENTATION_ROTATE_90) rotationAngle = 90;
        if (orientation == ExifInterface.oRIENTATION_ROTATE_180) rotationAngle = 180;
        if (orientation == ExifInterface.oRIENTATION_ROTATE_270) rotationAngle = 270;

        Matrix matrix = new Matrix();
        matrix.setRotate(rotationAngle,(float) resizedBitmap.getWidth() / 2,(float) resizedBitmap.getHeight() / 2);
        Bitmap rotatedBitmap = Bitmap.createBitmap(resizedBitmap,matrix,truE);
        resizedBitmap.recycle();
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
        rotatedBitmap.compress(Bitmap.CompressFormat.JPEG,90,bytes);

        thumbnailFile.createNewFile();
        FiLeoutputStream fo = new FiLeoutputStream(thumbnailFilE);
        fo.write(bytes.toByteArray());
        fo.close();

        //new File(filE).delete();  // Originalbild lö@R_696_10906@n

        return rotatedBitmap;
    }
}
}