multiple bitmaps versus drawables - performance and memory impact

Question

As you can see on the screenshot, I'm showing thumbnails in the ListView on the left side. Those thumbs are generated asynchronously. Anyway, the result for each row/item is a new Bitmap.

But I wonder if that's the best practise. This is because very often the background image (the climbing wall) is the same. Therefore I could generate a LayeredDrawable consisting of the background bitmap - which is the same for each row - and an own implementation of a Drawable which then draws the climbing route in its draw(Canvas) method.

Option 1: generate a new bitmap for each row/item.

Option 2: use a LayeredDrawable with the background bitmap and a dynamic Drawable.

Which option is best in terms of memory and CPU usage?

Answer 1

For my purposes I'm using a custom drawable and a BitmapDrawable within a LayerDrawable. The bitmap is the background and the custom drawable draws the line and holds. If the underlying data of the drawn line changes, I'm setting a dirty-flag so that the drawable is re-drawn on next cycle.