Android: Get thumbnail of image on SD card, given Uri of original image

Question

So i've got a Uri of an image the user chooses out of images off his SD card. And i'd like to display a thumbnail of that image, because obviously, the image could be huge and take up the whole screen. Anyone know how?

Answer 1

You can simply create thumbnail video and image using ThumnailUtil class of java

Bitmap resized = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(file.getPath()), width, height);


 public static Bitmap createVideoThumbnail (String filePath, int kind)

Added in API level 8 Create a video thumbnail for a video. May return null if the video is corrupt or the format is not supported.

Parameters filePath the path of video file kind could be MINI_KIND or MICRO_KIND

For more Source code of Thumbnail Util class

Developer.android.com

Answer 2

This code will do the job:

Bitmap getPreview(URI uri) {
    File image = new File(uri);

    BitmapFactory.Options bounds = new BitmapFactory.Options();
    bounds.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(image.getPath(), bounds);
    if ((bounds.outWidth == -1) || (bounds.outHeight == -1))
        return null;

    int originalSize = (bounds.outHeight > bounds.outWidth) ? bounds.outHeight
            : bounds.outWidth;

    BitmapFactory.Options opts = new BitmapFactory.Options();
    opts.inSampleSize = originalSize / THUMBNAIL_SIZE;
    return BitmapFactory.decodeFile(image.getPath(), opts);     
}

You may want to calculate the nearest power of 2 to use for inSampleSize, because it's said to be faster.

Answer 3

I believe this code is fastest way to generate thumbnail from file on SD card:

 public static Bitmap decodeFile(String file, int size) {
    //Decode image size
    BitmapFactory.Options o = new BitmapFactory.Options();
    o.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(file, o);

    //Find the correct scale value. It should be the power of 2.
    int width_tmp = o.outWidth, height_tmp = o.outHeight;
    int scale = (int)Maths.pow(2, (double)(scale-1));
    while (true) {
        if (width_tmp / 2 < size || height_tmp / 2 < size) {
            break;
        }
        width_tmp /= 2;
        height_tmp /= 2;
        scale++;
    }

    //Decode with inSampleSize
    BitmapFactory.Options o2 = new BitmapFactory.Options();
    o2.inSampleSize = scale;
    return BitmapFactory.decodeFile(file, o2);
}