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Backport weak layer reference utilities from 3.0
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nyalldawson committed Apr 19, 2017
1 parent 1cc2c41 commit a09ea451735b372e9ab90f042ac909bd3a757669
Showing with 399 additions and 2 deletions.
  1. +3 −0 src/core/CMakeLists.txt
  2. +57 −0 src/core/qgsmaplayerlistutils.h
  3. +220 −0 src/core/qgsmaplayerref.h
  4. +10 −0 src/core/qgsvectorlayerref.h
  5. +109 −2 tests/src/core/testqgsmaplayer.cpp
@@ -672,6 +672,8 @@ SET(QGIS_CORE_HDRS
qgslegendsettings.h
qgslogger.h
qgsmaphittest.h
qgsmaplayerlistutils.h
qgsmaplayerref.h
qgsmaplayerrenderer.h
qgsmaplayerstylemanager.h
qgsmapsettings.h
@@ -723,6 +725,7 @@ SET(QGIS_CORE_HDRS

qgsvectordataprovider.h
qgsvectorlayercache.h
qgsvectorlayerref.h
qgsvectorfilewriter.h
qgsvectorlayerdiagramprovider.h
qgsvectorlayereditutils.h
@@ -0,0 +1,57 @@
#ifndef QGSMAPLAYERLISTUTILS_H
#define QGSMAPLAYERLISTUTILS_H

//
// W A R N I N G
// -------------
//
// This file is not part of the QGIS API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//

#include <QPointer>

#include "qgsmaplayer.h"
#include "qgsmaplayerref.h"

/// @cond PRIVATE

inline QList<QgsMapLayer *> _qgis_listRefToRaw( const QList< QgsMapLayerRef > &layers )
{
QList<QgsMapLayer *> lst;
lst.reserve( layers.count() );
Q_FOREACH ( const QgsMapLayerRef &layer, layers )
{
if ( layer )
lst.append( layer.get() );
}
return lst;
}

inline QList< QgsMapLayerRef > _qgis_listRawToRef( const QList<QgsMapLayer *> &layers )
{
QList< QgsMapLayerRef > lst;
lst.reserve( layers.count() );
Q_FOREACH ( QgsMapLayer *layer, layers )
{
lst.append( QgsMapLayerRef( layer ) );
}
return lst;
}

inline void _qgis_removeLayers( QList< QgsMapLayerRef > &list, QList< QgsMapLayer *> layersToRemove )
{
QMutableListIterator<QgsMapLayerRef> it( list );
while ( it.hasNext() )
{
QgsMapLayerRef &ref = it.next();
if ( layersToRemove.contains( ref.get() ) )
it.remove();
}
}


///@endcond

#endif // QGSMAPLAYERLISTUTILS_H
@@ -0,0 +1,220 @@
/***************************************************************************
qgsmaplayerref.h
--------------------------------------
Date : January 2017
Copyright : (C) 2017 by Martin Dobias
Email : wonder dot sk at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/

#ifndef QGSMAPLAYERREF_H
#define QGSMAPLAYERREF_H

#include <QPointer>

#include "qgsmaplayer.h"
#include "qgsdataprovider.h"
#include "qgsmaplayerregistry.h"
#include "qgsvectorlayer.h"
#include "qgsvectordataprovider.h"
#include "qgsrasterlayer.h"
#include "qgsrasterdataprovider.h"

/** Internal structure to keep weak pointer to QgsMapLayer or layerId
* if the layer is not available yet.
* \note not available in Python bindings
*/
template<typename TYPE>
struct _LayerRef
{

/**
* Constructor for a layer reference from an existing map layer.
* The layerId, source, name and provider members will automatically
* be populated from this layer.
*/
_LayerRef( TYPE *l = nullptr )
: layer( l )
, layerId( l ? l->id() : QString() )
, source( l ? l->publicSource() : QString() )
, name( l ? l->name() : QString() )
, provider( layerProviderName( l ) )
{}

/**
* Constructor for a weak layer reference, using a combination of layer ID,
* \a name, public \a source and \a provider key.
*/
_LayerRef( const QString &id, const QString &name = QString(), const QString &source = QString(), const QString &provider = QString() )
: layer()
, layerId( id )
, source( source )
, name( name )
, provider( provider )
{}

/**
* Sets the reference to point to a specified layer.
*/
void setLayer( TYPE *l )
{
layer = l;
layerId = l ? l->id() : QString();
source = l ? l->publicSource() : QString();
name = l ? l->name() : QString();
provider = layerProviderName( l );
}

/**
* Returns true if the layer reference is resolved and contains a reference to an existing
* map layer.
*/
operator bool() const
{
return static_cast< bool >( layer.data() );
}

/**
* Forwards the to map layer.
*/
TYPE *operator->() const
{
return layer.data();
}

/**
* Returns a pointer to the layer, or nullptr if the reference has not yet been matched
* to a layer.
*/
TYPE *get() const
{
return layer.data();
}

//! Weak pointer to map layer
QPointer<TYPE> layer;

//! Original layer ID
QString layerId;

//! Weak reference to layer public source
QString source;
//! Weak reference to layer name
QString name;
//! Weak reference to layer provider
QString provider;

/**
* Returns true if a layer matches the weak references to layer public source,
* layer name and data provider contained in this layer reference.
* \see resolveWeakly()
*/
bool layerMatchesSource( QgsMapLayer *layer ) const
{
if ( layer->publicSource() != source ||
layer->name() != name )
return false;

if ( layerProviderName( layer ) != provider )
return false;

return true;
}

/**
* Resolves the map layer by attempting to find a layer with matching ID
* within the map layer registry. If found, this reference will be updated to match
* the found layer and the layer will be returned. If no matching layer is
* found, a nullptr is returned.
* \see resolveWeakly()
*/
TYPE *resolve()
{
if ( !layerId.isEmpty() )
{
if ( TYPE *l = qobject_cast<TYPE *>( QgsMapLayerRegistry::instance()->mapLayer( layerId ) ) )
{
setLayer( l );
return l;
}
}
return nullptr;
}

/**
* Resolves the map layer by attempting to find a matching layer
* in the map layer registry using a weak match.
*
* First, the layer is attempted to match to registry layers using the
* layer's ID (calling this method implicitly calls resolve()).
*
* Failing a match by layer ID, the layer will be matched by using
* the weak references to layer public source, layer name and data
* provider contained in this layer reference.
*
* If a matching layer is found, this reference will be updated to match
* the found layer and the layer will be returned. If no matching layer is
* found, a nullptr is returned.
* \see resolve()
* \see layerMatchesSource()
*/
TYPE *resolveWeakly()
{
// first try matching by layer ID
if ( resolve() )
return layer;

if ( !name.isEmpty() )
{
Q_FOREACH ( QgsMapLayer *l, QgsMapLayerRegistry::instance()->mapLayersByName( name ) )
{
if ( TYPE *tl = qobject_cast< TYPE *>( l ) )
{
if ( layerMatchesSource( tl ) )
{
setLayer( tl );
return tl;
}
}
}
}
return nullptr;
}

private:

static QString layerProviderName( const QgsMapLayer *layer )
{
if ( !layer )
return QString();

switch ( layer->type() )
{
case QgsMapLayer::VectorLayer:
{
const QgsVectorLayer *vl = qobject_cast< const QgsVectorLayer *>( layer );
return vl->dataProvider()->name();
}

case QgsMapLayer::RasterLayer:
{
const QgsRasterLayer *rl = qobject_cast< const QgsRasterLayer *>( layer );
return rl->dataProvider()->name();
}
case QgsMapLayer::PluginLayer:
return QString();
}
return QString();

}
};

typedef _LayerRef<QgsMapLayer> QgsMapLayerRef;

#endif // QGSMAPLAYERREF_H
@@ -0,0 +1,10 @@
#ifndef QGSVECTORLAYERREF_H
#define QGSVECTORLAYERREF_H

#include "qgsmaplayerref.h"

#include "qgsvectorlayer.h"

typedef _LayerRef<QgsVectorLayer> QgsVectorLayerRef;

#endif // QGSVECTORLAYERREF_H
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