The sheet list is returned as a copy of the cached list rather than a
reference to prevent external code from changing the list. While not as
performant, it eliminates the risk of the sheet list being altered in
ways that could break the schematic. The sheet list should only be
updated by calling SCHEMATIC::RefreshHierarchy() when any appropriate
sheet changes are made.
Note to developers: there is something inherently different about how the
QA tests are loading and handling schematics versus the schematic editor.
Using the cached sheet list for the SCHEMATIC object will cause some QA
test to fail. This is why SCHEMATIC::Hierarchy() has not replaced
SCHEMATIC::BuildSheetListSortedByPageNumbers() everywhere.
Also removes the side-effect that SCH_SHEET_LIST's
c'tor would sort the list (and write virtual page
numbers) anytime the starting sheet was the root.
Also, definitely don't build a SHEET_LIST (sorted or
otherwise) if you're not even going to use it.
Also don't build SCH_SHEET_LISTs on idle events. Better
to just always have the Next Sheet button enabled (we
already beep if you click it and there's no next sheet).
Also, use a SCREEN_LIST when you can. It's much cheaper
to create.
Prior to this change, the schematic connectivity was updated any time a
change was made to a connectable object. Now the connectivity is only
updated when an object change actually affects the connectivity. Other
properties like line width, fill type, custom fonts, etc. will not cause
the connectivity graph to be rebuilt.
The SCH_COMMIT flag SKIP_CONNECTIVITY has been removed. All schematic
objects can test if they are connectable and if there have been changes
to any connection properties that require a connectivity rebuild.
Remove duplicate rebuild connectivity calls from editor control tool.
This was causing the tangling end test to get called four times on every
undo and redo action because the dangling end test is already called in
the connectivity graph calculation code.
Update connectivity when changing label names which fixes an unreported
connectivity bug.
