void IndexBuilder::writeSnapshots(Reader &reader, KZip &zip)
{
static const qint64 SNAPSHOT_INTERVAL_MS = 1000; // snapshot interval in milliseconds
static const int SNAPSHOT_MIN_ACTIONS = 200; // minimum number of actions between snapshots
paintcore::LayerStack image;
net::LayerListModel layermodel;
canvas::StateTracker statetracker(&image, &layermodel, 1);
MessageRecord msg;
int snapshotCounter = 0;
QElapsedTimer timer;
timer.start();
while(true) {
if(_abortflag.load())
return;
msg = reader.readNext();
if(msg.status == MessageRecord::END_OF_RECORDING)
break;
else if(msg.status == MessageRecord::INVALID)
continue;
protocol::MessagePtr m(msg.message);
if(m->isCommand()) {
statetracker.receiveCommand(m);
++snapshotCounter;
}
// Save a snapshot every SNAPSHOT_INTERVAL or at every marker. (But no more often than SNAPSHOT_MIN_ACTIONS)
// Note. We use the actual elapsed rendering time to decide when to snapshot. This means that (ideally),
// the time it takes to jump to a snapshot is at most SNAPSHOT_INTERVAL milliseconds (+ the time it takes to load the snapshot)
if(m_index.snapshots().isEmpty() || ((timer.hasExpired(SNAPSHOT_INTERVAL_MS) || m->type() == protocol::MSG_MARKER) && snapshotCounter>=SNAPSHOT_MIN_ACTIONS)) {
qint64 streampos = reader.filePosition();
emit progress(streampos);
canvas::StateSavepoint sp = statetracker.createSavepoint(-1);
QBuffer buf;
buf.open(QBuffer::ReadWrite);
{
QDataStream ds(&buf);
sp.toDatastream(ds);
}
int snapshotIdx = m_index.m_snapshots.size();
zip.writeFile(QString("snapshot-%1").arg(snapshotIdx), buf.data());
m_index.m_snapshots.append(SnapshotEntry(streampos, reader.currentIndex()));
snapshotCounter = 0;
timer.restart();
}
}
}
