Avoiding Out of Memory Error with Bitmap Factory, Even When Resizing Isn't an Issue?

Question

I've researched at least 10 similar topics on SO, however, none have reached a definitive answer for me allowing me to avoid the Out of Memory error Bitmaps are known for.

Taking into consideration the advice from these previous questions, I constructed the following method setBipmapFromPath to produce an optimally sized (both in dimensions and kilobytes) wallpaper image from a file path. This method works fine on a large RAM device like my G2, however, it crashes in an emulator with 1.5GB of RAM using a 256kb picture.

I welcome any criticism that will help me prevent the Out of Memory error. My hope is to also ensure the image can still act as a proper background image, as in, fill the screen of the device reasonably without insane stretch marks.

My methods:

public void recycleWallpaperBitmap() {
    if (mBitmap != null) {

        mBitmap.recycle();
        mBitmap = null;
    }
}

 private void setBitmapFromPath() {

    // Recycle the bitmap just in case.
    recycleWallpaperBitmap();

    String path = mProfileManager.getWallpaperPath();

    if (path != null) {

        WindowManager wm = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();

        int displayWidth = display.getWidth();  // deprecated
        int displayHeight = display.getHeight();  // deprecated

        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = false;

        mBitmap = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(path, options),
                displayWidth, displayHeight);

    }
}

Answer 1

This method works fine on a large RAM device like my G2, however, it crashes in an emulator with 1.5GB of RAM using a 256kb picture.

It will fail on the G2 as well, depending on where and when you call this method. Your "256kb" picture will take up several MB of heap space, and there is no assurance that you have that amount of heap space available in a single contiguous block.

Also, I would not use a class and method designed for creating thumbnails will be suitable for creating wallpaper-sized images.

I welcome any criticism that will help me prevent the Out of Memory error.

Use inSampleSize on your BitmapFactory.Options to downsample the image to closer to the right size while it is being read in.

Then, dump your use of ThumbnailUtils and allow your ImageView to scale it the rest of the way, to avoid making yet another copy of the image.

Bonus points for using inBitmap instead of junking and re-allocating your Bitmap every time, since the screen size is not changing, and therefore your wallpaper dimensions are not changing.

These techniques and more are covered in the developer documentation.