Open image dialog/GridView is very slow

问题

What I have

I have an "open image dialog" in an activity. This "dialog" only shows folders and compatible images. For this I have a layer with a gridview that I fill with rows that contains an image and a text.

The text is for the name of the file and the image is for a preview of the image.

My problem

The dialog works well if the folder that I'm seeing doesn't have lots of images. I'm working on a SII and when I try to open the camera album (photos of 8Mpx) it goes very slow with my code, even each time a new row is redrawed.

My code

I think the main problem resides in the creation of the preview images because if I delete this part all works fine. For the images, I have:

  @Override
public View getView(int position, View convertView, ViewGroup parent) {
   View grid;

   if(convertView==null){
       grid = new View(mContext);
       LayoutInflater inflater=getLayoutInflater();
       grid=inflater.inflate(R.layout.row, parent, false);
   }else{
       grid = (View)convertView;
   }

   ImageView icon = (ImageView)grid.findViewById(R.id.file_image);
   TextView label = (TextView)grid.findViewById(R.id.file_text);
   label.setText(item.get(position));
    if (item.get(position).equals("/")){
        icon.setImageResource(R.drawable.folderupup);
    }else if (item.get(position).endsWith("../")) {
        icon.setImageResource(R.drawable.folderup);
    }else if (item.get(position).endsWith("/")) {    
        icon.setImageResource(R.drawable.folder);
    }else{
        Bitmap b = BitmapFactory.decodeFile(path.get(position));
        Bitmap b2 = Bitmap.createScaledBitmap(b, 55, 55, false);
        icon.setImageBitmap(b2);
    }

   return grid;
  }
 }

回答1:

In somewhere, the code calls this (data is the full pathname of the image):

DiskLruCache.Editor editor = mHttpDiskCache.edit(key);
if (editor != null) {
       if (downloadUrlToStream(data,editor.newOutputStream(DISK_CACHE_INDEX))) {
             editor.commit();
       } else {
             editor.abort();
       }
}

because I don't know how to change it, I modified the url receptor so now instead of reading from the net it reads from a file:

    public boolean downloadUrlToStream(String urlString, OutputStream outputStream) {
        disableConnectionReuseIfNecessary();
        HttpURLConnection urlConnection = null;
        BufferedOutputStream out = null;
        BufferedInputStream in = null;

        try {

            in = new BufferedInputStream(new FileInputStream(new File(urlString)), IO_BUFFER_SIZE);
            out = new BufferedOutputStream(outputStream, IO_BUFFER_SIZE);

            int b;
            while ((b = in.read()) != -1) {
                out.write(b);
            }
            return true;
        } catch (final IOException e) {
            Log.e(TAG, "Error in downloadBitmap - " + e);
        } finally {
            if (urlConnection != null) {
                urlConnection.disconnect();
            }
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (final IOException e) {}
        }
        return false;
    }

But the gridview load the images very slowly. I think it's because the last method. How can I do it better?

回答2:

Finally I did all that the Android page said without doing anything for the cache. Now the list loads fast. Maybe I could add a memory cache as Wenhui pointed but it is so fast that it doesn't matter for my purposes.

The test has been done on a SII with a folder containing around 400 with 8Mpx

来源：https://stackoverflow.com/questions/12789939/open-image-dialog-gridview-is-very-slow

标签

android

gridview