Displaying images from a specific folder on the SDCard using a gridview

Question

I'm attempting to create a gridview that is loaded with images from a specific folder that resides on an SDCard. The path to the folder is known, ("/sdcard/pictures") , but in the examples I've seen online I am unsure how or where to specify the path to the pictures folder I want to load images from. I have read through dozens of tutorials, even the HelloGridView tutorial at developer.android.com but those tutorials do not teach me what i am seeking.

Every tutorial I have read so far has either:

A) called the images as a Drawable from the /res folder and put them into an array to be loaded, not using the SDCard at all.

B) Accessed all pictures on the SDCard using the MediaStore but not specifying how to set the path to the folder I want to display images form

or

C) Suggested using BitmapFactory, which I haven't the slightest clue how to use.

If I'm going about this in the wrong way, please let me know and direct me toward the proper method to do what I'm trying to do.

Answer 1

OK, after many iterations of trying, I finally have an example that works and I thought I'd share it. My example queries the images MediaStore, then obtains the thumbnail for each image to display in a view. I am loading my images into a Gallery object, but that is not a requirement for this code to work:

Make sure you have a Cursor and int for the column index defined at the class level so that the Gallery's ImageAdapter has access to them:

private Cursor cursor;
private int columnIndex;

First, obtain a cursor of image IDs located in the folder:

Gallery g = (Gallery) findViewById(R.id.gallery);
// request only the image ID to be returned
String[] projection = {MediaStore.Images.Media._ID};
// Create the cursor pointing to the SDCard
cursor = managedQuery( MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
        projection, 
        MediaStore.Images.Media.DATA + " like ? ",
        new String[] {"%myimagesfolder%"},  
        null);
// Get the column index of the image ID
columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media._ID);
g.setAdapter(new ImageAdapter(this));

Then, in the ImageAdapter for the Gallery, obtain the thumbnail to display:

public View getView(int position, View convertView, ViewGroup parent) {
    ImageView i = new ImageView(context);
    // Move cursor to current position
    cursor.moveToPosition(position);
    // Get the current value for the requested column
    int imageID = cursor.getInt(columnIndex);
    // obtain the image URI
    Uri uri = Uri.withAppendedPath( MediaStore.Images.Media.EXTERNAL_CONTENT_URI, Integer.toString(imageID) );
    String url = uri.toString();
    // Set the content of the image based on the image URI
    int originalImageId = Integer.parseInt(url.substring(url.lastIndexOf("/") + 1, url.length()));
    Bitmap b = MediaStore.Images.Thumbnails.getThumbnail(getContentResolver(),
                    originalImageId, MediaStore.Images.Thumbnails.MINI_KIND, null);
    i.setImageBitmap(b);
    i.setLayoutParams(new Gallery.LayoutParams(150, 100));
    i.setScaleType(ImageView.ScaleType.FIT_XY);
    i.setBackgroundResource(mGalleryItemBackground);
    return i;
}

I guess the most important section of this code is the managedQuery that demonstrates how to use MediaStore queries to filter a list of image files in a specific folder.