plasma-framework/dataengine.cpp
Aaron J. Seigo 2638b6031b * introduce a NullEngine
* return an instance of the NullEngine on engine loading failure; this way applets don't have to test for engine existence and can just assume something gets returned
* DataEngine::isValid() in case someone really cares to know whether they have a non-functional engine (e.g. the NullEngine)

svn path=/trunk/KDE/kdebase/workspace/lib/plasma/; revision=670900
2007-06-02 22:23:26 +00:00

283 lines
7.1 KiB
C++

/*
* Copyright (C) 2006 Aaron Seigo <aseigo@kde.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License version 2 as
* published by the Free Software Foundation
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details
*
* You should have received a copy of the GNU Library General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "dataengine.h"
#include <QQueue>
#include <QTimer>
#include <QVariant>
#include <KDebug>
#include "datasource.h"
namespace Plasma
{
class DataEngine::Private
{
public:
Private(DataEngine* e)
: engine(e),
limit(0),
valid(true)
{
updateTimer = new QTimer(engine);
updateTimer->setSingleShot(true);
}
DataSource* source(const QString& sourceName)
{
DataSource::Dict::const_iterator it = sources.find(sourceName);
if (it != sources.constEnd()) {
DataSource* s = it.value();
if (limit > 0) {
QQueue<DataSource*>::iterator it = sourceQueue.begin();
while (it != sourceQueue.end()) {
if (*it == s) {
sourceQueue.erase(it);
break;
}
++it;
}
sourceQueue.enqueue(s);
}
return it.value();
}
kDebug() << "DataEngine " << engine->objectName()
<< ": could not find DataSource " << sourceName
<< ", creating" << endl;
DataSource* s = new DataSource(engine);
s->setObjectName(sourceName);
sources.insert(sourceName, s);
if (limit > 0) {
trimQueue();
sourceQueue.enqueue(s);
}
emit engine->newDataSource(sourceName);
return s;
}
void trimQueue()
{
while (sourceQueue.count() >= limit) {
DataSource* punted = sourceQueue.dequeue();
engine->removeDataSource(punted->objectName());
}
}
void queueUpdate()
{
if (updateTimer->isActive()) {
return;
}
updateTimer->start(0);
}
QAtomic ref;
DataSource::Dict sources;
QQueue<DataSource*> sourceQueue;
DataEngine* engine;
QTimer* updateTimer;
QString icon;
uint limit;
bool valid;
};
DataEngine::DataEngine(QObject* parent)
: QObject(parent),
d(new Private(this))
{
connect(d->updateTimer, SIGNAL(timeout()), this, SLOT(checkForUpdates()));
//FIXME: we should delay this call; to when is the question.
init();
}
DataEngine::~DataEngine()
{
//kDebug() << objectName() << ": bye bye birdy! " << endl;
delete d;
}
QStringList DataEngine::dataSources() const
{
return d->sources.keys();
}
void DataEngine::connectSource(const QString& source, QObject* visualization) const
{
DataSource* s = d->source(source);
connect(s, SIGNAL(updated(QString,Plasma::DataEngine::Data)),
visualization, SLOT(updated(QString,Plasma::DataEngine::Data)));
QMetaObject::invokeMethod(visualization, SLOT(updated(QString,Plasma::DataEngine::Data)),
Q_ARG(QString, s->objectName()),
Q_ARG(Plasma::DataEngine::Data, s->data()));
}
void DataEngine::connectAllSources(QObject* visualization) const
{
foreach (const DataSource* s, d->sources) {
connect(s, SIGNAL(updated(QString,Plasma::DataEngine::Data)),
visualization, SLOT(updated(QString,Plasma::DataEngine::Data)));
}
foreach (const DataSource* s, d->sources) {
QMetaObject::invokeMethod(visualization,
SLOT(updated(QString,Plasma::DataEngine::Data)),
Q_ARG(QString, s->objectName()),
Q_ARG(Plasma::DataEngine::Data, s->data()));
}
}
DataEngine::Data DataEngine::query(const QString& source) const
{
Q_UNUSED(source)
DataSource* s = d->source(source);
return s->data();
}
void DataEngine::init()
{
// default implementation does nothing. this is for engines that have to
// start things in motion external to themselves before they can work
}
void DataEngine::setData(const QString& source, const QVariant& value)
{
setData(source, source, value);
}
void DataEngine::setData(const QString& source, const QString& key, const QVariant& value)
{
DataSource* s = d->source(source);
s->setData(key, value);
d->queueUpdate();
}
void DataEngine::addSource(DataSource* source)
{
DataSource::Dict::const_iterator it = d->sources.find(source->objectName());
if (it != d->sources.constEnd()) {
kDebug() << "source named \"" << source->objectName() << "\" already exists." << endl;
return;
}
d->sources.insert(source->objectName(), source);
emit newDataSource(source->objectName());
}
void DataEngine::setSourceLimit(uint limit)
{
if (d->limit == limit) {
return;
}
d->limit = limit;
if (d->limit > 0) {
d->trimQueue();
} else {
d->sourceQueue.clear();
}
}
/*
Plasma::DataSource* DataEngine::createDataSource(const QString& source, const QString& domain)
{
Q_UNUSED(domain)
//TODO: add support for domains of sources
if (d->source(source)) {
kDebug() << "DataEngine " << objectName() << ": source " << source << " already exists " << endl;
return s
}
}*/
void DataEngine::removeDataSource(const QString& source)
{
DataSource::Dict::iterator it = d->sources.find(source);
if (it != d->sources.end()) {
emit dataSourceRemoved(it.key());
d->sources.erase(it);
}
}
void DataEngine::clearAllDataSources()
{
QMutableHashIterator<QString, Plasma::DataSource*> it(d->sources);
while (it.hasNext()) {
it.next();
emit dataSourceRemoved(it.key());
delete it.value();
it.remove();
}
}
void DataEngine::ref()
{
d->ref.ref();
}
void DataEngine::deref()
{
d->ref.deref();
}
bool DataEngine::isUsed() const
{
return d->ref != 0;
}
bool DataEngine::isValid() const
{
return d->valid;
}
bool DataEngine::setValid(bool valid)
{
d->valid = valid;
}
void DataEngine::setIcon(const QString& icon)
{
d->icon = icon;
}
QString DataEngine::icon() const
{
return d->icon;
}
void DataEngine::checkForUpdates()
{
QHashIterator<QString, Plasma::DataSource*> it(d->sources);
while (it.hasNext()) {
it.next();
it.value()->checkForUpdate();
}
}
}
#include "dataengine.moc"