When new bitmaps are added and the underlying Common::Array needs
to move to expand, this invalidates all pointers to bitmaps, which
makes it basically impossible to use the bitmap segment since you
never know if a reference is going to be invalidated due to an
array move.
To solve this, BitmapTable is changed to hold pointers to
SciBitmaps that are allocated separately on the heap instead, so
when those bitmaps are looked up, the resulting pointers are valid
for the lifetime of the bitmap, instead of the lifetime of the
Common::Array used internally by BitmapTable.
In the original engine this would have simply resulted in no draw,
but ScummVM is more strict about it. It is not 100% clear whether
these are normal and should be allowed or not, so for the moment
we'll emit a warning whenever a zero-dimension show rect is seen.
For now they only seem to be generated by plane transitions, and
these zero-dimension screen items cannot simply be omitted because
the 2.1early transitions code requires a fixed number of screen
items per step.
This commit implements all of the known plane transitions from
SCI2 through SCI2.1mid games. Because kSetShowStyle is always
called indirectly via the Styler game script, it is difficult to
find all the places where transitions are used. As such,
transitions that appeared to never be used have been added as
stubs which will trigger a game crash with a message to report
what was being done, so any missed transition types can be
identified quickly and then implemented.
Bitmaps in ScrollWindow and Robot code are managed by the kernel
and not by game scripts, although they must be able to be
referenced through a reg_t. To prevent incorrect GC of bitmaps
that are in use but not referenced by any game script, explicit
memory management of hunk entries can be enabled.
Borja Lorente
Paul Gilbert
Eugene Sandulenko
Colin Snover
Bastien Bouclet