98 lines
4.1 KiB
C++
98 lines
4.1 KiB
C++
/*
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SPDX-FileCopyrightText: 2011 Aaron Seigo <aseigo@kde.org>
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SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "sourcesOnRequest.h"
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#include <Plasma/DataContainer>
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#include <QStandardItemModel>
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/*
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This DataEngine shows how to created sources on demand as they are requested
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and update them on visualization-requested update intervals.
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It also shows how to bind and arbitrary QAbstractItemModel to a source
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*/
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SourcesOnRequestEngine::SourcesOnRequestEngine(QObject *parent, const QVariantList &args)
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: Plasma::DataEngine(parent, args)
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{
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// We've passed the constructor's args to our parent class.
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// We're done for now!
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}
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bool SourcesOnRequestEngine::sourceRequestEvent(const QString &source)
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{
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// When this method is called we can assume that:
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// * the source does not exist yet
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// * the source name parameter passed in is not an empty string
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// * we are free to reject creating the source if we wish
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// We're going to reject any sources that start with the letter 'a'
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// to demonstrate how to reject a request in a DataEngine.
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if (source.startsWith(QLatin1Char('a')) || source.startsWith(QLatin1Char('A'))) {
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return false;
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}
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// For every other source, we're going to start an update count for it.
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// Critically, we create a source before returning that has the exact
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// same key as the source string. We MUST NOT create a source of a different
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// name as that will cause unexpected results for the visualization.
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// In such a case the DataEngine will remain happy and Do The Right Thing(tm)
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// but the visualization will not get the source connected to it as it
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// expects. So ALWAYS key the new data by the source string as below:
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setData(source, QStringLiteral("Update Count"), 0);
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if (!modelForSource(source)) {
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QStandardItemModel *m = new QStandardItemModel;
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m->appendRow(new QStandardItem(QStringLiteral("Item1, first update")));
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m->appendRow(new QStandardItem(QStringLiteral("Item2, first update")));
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m->appendRow(new QStandardItem(QStringLiteral("Item3, first update")));
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setModel(source, m);
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}
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// as we successfully set up the source, return true
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return true;
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}
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bool SourcesOnRequestEngine::updateSourceEvent(const QString &source)
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{
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// Whenever a visualization has requested an update, such as when passing
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// an update interval to DataEngine::connectSource, this method will be called.
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// When this method is called we can assume that:
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// * the source exists
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// * it hasn't been updated more frequently than the minimum update interval
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//
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// If not data is set in this method, then the update is skipped for the visualiation
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// and that is just fine.
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//
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// We can also set data for other sources here if we wish, but as with
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// sourceRequestEvent this may not be what the visualization expects. Unlike in
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// sourceRequestEvent, however, this will result in expected behavior: visualizations
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// connected to the sources which have setData called for them will be notified
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// of these changes.
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const int updateCount = containerForSource(source)->data().value(QStringLiteral("Update Count")).toInt() + 1;
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setData(source, QStringLiteral("Update Count"), updateCount);
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QStandardItemModel *m = qobject_cast<QStandardItemModel *>(modelForSource(source));
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if (m) {
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m->clear();
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m->appendRow(new QStandardItem(QStringLiteral("Item1, update %1").arg(updateCount)));
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m->appendRow(new QStandardItem(QStringLiteral("Item2, update %1").arg(updateCount)));
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m->appendRow(new QStandardItem(QStringLiteral("Item3, update %1").arg(updateCount)));
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}
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// Since we updated the source immediately here, we need to return true so the DataEngine
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// knows to continue with the update notification for visualizations.
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return true;
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}
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// export the plugin; use the plugin name and the class name
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K_EXPORT_PLASMA_DATAENGINE_WITH_JSON(org.kde.examples.sourcesOnRequest, SourcesOnRequestEngine, "plasma-dataengine-example-sourcesOnRequest.json")
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// include the moc file so the build system makes it for us
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#include "sourcesOnRequest.moc"
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