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Author: nikolaus
Date: 10.12.2009
* Damage system 3 ----
Currently, the damage system has the following drawbacks:
- Damages are created on the heap.
- Each damage handler gets a list of all damages, irrespective if document
or view related. If an object wants only specific damages it has to
traverse the whole list.
The desired features were/are:
- Collect damages while processing a command and flush them at once.
- Do not block the UI for too long.
- Prevent many public methods (in Map/Sheet), which only purpose is to emit
a signal.
Thoughts/Proposed solution:
- Implement the following methods, that emit different signals depending on
the damage:
void Sheet::addDamage(CellDamage::Changes, const Region&);
void Sheet::addDamage(SheetDamage::Changes);
void Map::addDamage(WorkbookDamage::Changes);
They still collect damages though.
- The enums can be moved into Map/Sheet. Or a DamageHandler object can act
as signal emitter, so no heavy recompilation after changes on the system.
- Principally, provide one signal for each damage. Combine several damages
to one signal only where appropriate.
- Use Qt::QueuedConnections to prevent blocking the UI for too long. This
would create events behind the scenes -> heap.
- To prevent the View from processing damages of all sheets, even if they
are not the active one, connect and disconnect signals/slots on changing
the active sheet.
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