Instead of each card being responsible for painting its own bitmaps, we
now have a CardPainter which is responsible for this. It paints a given
card the first time it is requested, and then re-uses that bitmap when
requested in the future. This saves memory for duplicate cards (such as
in Spider where several sets of the same suit are used) or unused ones
(for example, the inverted cards which are only used by Hearts). It
also means we don't throw away bitmaps and then re-create identical
ones when starting a new game.
We get some nice memory savings from this:
| | Before | After | Before (Virtual) | After (Virtual) |
|:----------|---------:|---------:|-----------------:|----------------:|
| Hearts | 12.2 MiB | 9.3 MiB | 25.1 MiB | 22.2 MiB |
| Spider | 12.1 MiB | 10.1 MiB | 29.2 MiB | 22.9 MiB |
| Solitaire | 16.4 MiB | 9.0 MiB | 25.0 MiB | 21.9 MiB |
All these measurements taken from x86_64 build, from a fresh launch of
each game after the animation has finished, but without making any
moves. The Hearts value will go up once inverted cards start being
requested.
