Question

I’m trying to implement an image gallery in android.
The code based on http://www.mobisoftinfotech.com/blog/android/android-gallery-widget-example-and-tutorial/ and i’ve changed some details.

I’m using WeakReference and it seems, that when i’ve too many bitmaps, the garbage collector destroys my weakreferences. How can i handle this?

I get my bitmaps via this function:

    public static WeakReference<Bitmap> getBitmap(String imageName, int width,
        int height) {
    String pathToImage = getPathToImage(imageName);
    Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(pathToImage, options);

    /*
     * Calculate inSampleSize
     */
    options.inSampleSize = calculateInSampleSize(options, width, height);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;

    WeakReference<Bitmap> scaledBitmap = new WeakReference<Bitmap>(
            BitmapFactory.decodeFile(pathToImage, options));
    return scaledBitmap;
}

And i’ve taken the Solution 320×480, so i think it is not this big…

When the gallery has more than 3 pictures, some of them aren’t displayed.

Is the gallery-tutorial not that good? Are there other ways to implement this?

Thank you!

Answer 1

Instead of using soft references, you should take a look at the lrucache class (it became available in honeycomb, but is part of the android-support library.

You can read more about it here : http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html
It’s pretty convenient : use this and you won’t have to handle the memory yourself with weak references 🙂