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Rework layer dependencies

A new class QgsMapLayerDependency allows to represent different kinds
of dependencies between layers.
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Hugo Mercier
Hugo Mercier committed Aug 31, 2016
1 parent 1a5a7c5 commit 0749ba43bae401c10885b1a4f5a30677750affd8
@@ -9,6 +9,7 @@ PyQgsSipCoverage
PyQgsSpatialiteProvider
PyQgsVirtualLayerDefinition
PyQgsVirtualLayerProvider
PyQgsLayerDependencies
qgis_composermapgridtest
qgis_composerutils
ProcessingGrass7AlgorithmsImageryTest
@@ -80,6 +80,7 @@
%Include qgslogger.sip
%Include qgsmaphittest.sip
%Include qgsmaplayer.sip
%Include qgsmaplayerdependency.sip
%Include qgsmaplayerlegend.sip
%Include qgsmaplayermodel.sip
%Include qgsmaplayerproxymodel.sip
@@ -678,20 +678,29 @@ class QgsMapLayer : QObject

/**
* Sets the list of layers that may modify data/geometries of this layer when modified.
* @see dataDependencies
* @see dependencies()
*
* @param layersIds IDs of the layers that this layer depends on
* @returns false if a dependency cycle has been detected (the change dependency set is not changed in that case)
*/
virtual bool setDataDependencies( const QSet<QString>& layersIds );

/**
* Gets the list of layers that may modify data/geometries of this layer when modified.
* @see setDataDependencies
* Sets the list of layers that may modify data/geometries of this layer when modified.
* @see dependencies()
*
* @param set of QgsMapLayerDependency. Only user-defined dependencies will be added
* @returns false if a dependency cycle has been detected (the change dependency set is not changed in that case)
*/
bool setDataDependencies( const QSet<QgsMapLayerDependency>& layers );

/**
* Gets the list of dependencies. This includes data dependencies set by the user (@see setDataDependencies)
* as well as dependencies given by the provider
*
* @returns IDs of the layers that this layer depends on
* @returns a set of QgsMapLayerDependency
*/
virtual QSet<QString> dataDependencies() const;
virtual QSet<QgsMapLayerDependency> dependencies() const;

signals:

@@ -785,5 +794,5 @@ class QgsMapLayer : QObject
void setError( const QgsError &error );

//! Checks if new change dependency candidates introduce a cycle
bool hasDataDependencyCycle( const QSet<QString>& layersIds ) const;
bool hasDataDependencyCycle( const QSet<QgsMapLayerDependency>& layersIds ) const;
};
@@ -0,0 +1,36 @@
class QgsMapLayerDependency
{
%TypeHeaderCode
#include "qgsmaplayerdependency.h"
%End
public:
//! Type of dependency
enum Type
{
PresenceDependency = 1, // The layer must be already present (in the registry) for this dependency to be resolved
DataDependency = 2 // The layer may be invalidated by data changes on another layer
};

//! Origin of the dependency
enum Origin
{
FromProvider = 0, // Dependency given by the provider, the user cannot change it
FromUser = 1 // Dependency given by the user
};

//! Standard constructor
QgsMapLayerDependency( QString layerId, Type type = DataDependency, Origin origin = FromUser );

//! Return the dependency type
Type type() const;

//! Return the dependency origin
Origin origin() const;

//! Return the ID of the layer this dependency depends on
QString layerId() const;

bool operator==( const QgsMapLayerDependency& other ) const;
};


@@ -368,7 +368,7 @@ class QgsVectorDataProvider : QgsDataProvider
/**
* Get the list of layer ids on which this layer depends. This in particular determines the order of layer loading.
*/
virtual QSet<QString> layerDependencies() const;
virtual QSet<QgsMapLayerDependency> dependencies() const;

signals:
/** Signals an error in this provider */
@@ -421,12 +421,6 @@ class QgsVectorLayer : QgsMapLayer

const QList<QgsVectorJoinInfo> vectorJoins() const;

/**
* Gets the list of layer ids on which this layer depends, as returned by the provider.
* This in particular determines the order of layer loading.
*/
virtual QSet<QString> layerDependencies() const;

/**
* Sets the list of layers that may modify data/geometries of this layer when modified.
* This is meant mainly to declare database triggers between layers.
@@ -439,12 +433,12 @@ class QgsVectorLayer : QgsMapLayer
bool setDataDependencies( const QSet<QString>& layersIds );

/**
* Gets the list of layers that may modify data/geometries of this layer when modified.
* @see setDataDependencies
* Gets the list of dependencies. This includes data dependencies set by the user (@see setDataDependencies)
* as well as dependencies given by the provider
*
* @returns IDs of the layers that this layer depends on
* @returns a set of QgsMapLayerDependency
*/
QSet<QString> dataDependencies() const;
virtual QSet<QgsMapLayerDependency> dependencies() const;

/**
* Add a new field which is calculated by the expression specified
@@ -302,7 +302,11 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(

mLayersDependenciesTreeGroup->setVisible( Qt::Unchecked );

QSet<QString> dependencySources = mLayer->dataDependencies();
QSet<QString> dependencySources;
Q_FOREACH ( const QgsMapLayerDependency& dep, mLayer->dependencies() )
{
dependencySources << dep.layerId();
}
Q_FOREACH ( QgsLayerTreeLayer* layer, mLayersDependenciesTreeGroup->findLayers() )
{
layer->setVisible( dependencySources.contains( layer->layerId() ) ? Qt::Checked : Qt::Unchecked );
@@ -1681,61 +1681,77 @@ void QgsMapLayer::setExtent( const QgsRectangle &r )
mExtent = r;
}

static QList<const QgsMapLayer*> _depOutEdges( const QgsMapLayer* vl, const QgsMapLayer* that, const QSet<QString>& layersIds )
static QList<const QgsMapLayer*> _depOutEdges( const QgsMapLayer* vl, const QgsMapLayer* that, const QSet<QgsMapLayerDependency>& layers )
{
QList<const QgsMapLayer*> lst;
if ( vl == that )
{
Q_FOREACH ( QString layerId, layersIds )
Q_FOREACH ( const QgsMapLayerDependency& dep, layers )
{
if ( const QgsMapLayer* l = QgsMapLayerRegistry::instance()->mapLayer( layerId ) )
if ( const QgsMapLayer* l = QgsMapLayerRegistry::instance()->mapLayer( dep.layerId() ) )
lst << l;
}
}
else
{
Q_FOREACH ( QString layerId, vl->dataDependencies() )
Q_FOREACH ( const QgsMapLayerDependency& dep, vl->dependencies() )
{
if ( const QgsMapLayer* l = QgsMapLayerRegistry::instance()->mapLayer( layerId ) )
if ( const QgsMapLayer* l = QgsMapLayerRegistry::instance()->mapLayer( dep.layerId() ) )
lst << l;
}
}
return lst;
}

static bool _depHasCycleDFS( const QgsMapLayer* n, QHash<const QgsMapLayer*, int>& mark, const QgsMapLayer* that, const QSet<QString>& layersIds )
static bool _depHasCycleDFS( const QgsMapLayer* n, QHash<const QgsMapLayer*, int>& mark, const QgsMapLayer* that, const QSet<QgsMapLayerDependency>& layers )
{
if ( mark.value( n ) == 1 ) // temporary
return true;
if ( mark.value( n ) == 0 ) // not visited
{
mark[n] = 1; // temporary
Q_FOREACH ( const QgsMapLayer* m, _depOutEdges( n, that, layersIds ) )
Q_FOREACH ( const QgsMapLayer* m, _depOutEdges( n, that, layers ) )
{
if ( _depHasCycleDFS( m, mark, that, layersIds ) )
if ( _depHasCycleDFS( m, mark, that, layers ) )
return true;
}
mark[n] = 2; // permanent
}
return false;
}

bool QgsMapLayer::hasDataDependencyCycle( const QSet<QString>& layersIds ) const
bool QgsMapLayer::hasDataDependencyCycle( const QSet<QgsMapLayerDependency>& layers ) const
{
QHash<const QgsMapLayer*, int> marks;
return _depHasCycleDFS( this, marks, this, layersIds );
return _depHasCycleDFS( this, marks, this, layers );
}

QSet<QgsMapLayerDependency> QgsMapLayer::dependencies() const
{
return mDataDependencies;
}

bool QgsMapLayer::setDataDependencies( const QSet<QString>& layersIds )
{
if ( hasDataDependencyCycle( layersIds ) )
QSet<QgsMapLayerDependency> deps;
Q_FOREACH ( QString layerId, layersIds )
{
deps << QgsMapLayerDependency( layerId );
}
if ( hasDataDependencyCycle( deps ) )
return false;

mDataDependencies = layersIds;
mDataDependencies = deps;

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@m-kuhn

m-kuhn Aug 31, 2016

Member

It would also be good to send a signal when this is set so the rest of the world can subscribe to notifications.

I always do setters like this:

if ( dependencies == mDependencies )
  return;

// additional checks

mDependencies = dependencies;
emit dependenciesChanged();

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@mhugo

mhugo Aug 31, 2016

I'll add that, thanks

return true;
}

QSet<QString> QgsMapLayer::dataDependencies() const
bool QgsMapLayer::setDataDependencies( const QSet<QgsMapLayerDependency>& layers )
{
return mDataDependencies;
QSet<QString> deps;
Q_FOREACH ( const QgsMapLayerDependency& dep, layers )
{
if ( dep.origin() == QgsMapLayerDependency::FromUser && dep.type() == QgsMapLayerDependency::DataDependency )
deps << dep.layerId();
}
return setDataDependencies( deps );
}
@@ -32,6 +32,7 @@
#include "qgsrectangle.h"
#include "qgscoordinatereferencesystem.h"
#include "qgsrendercontext.h"
#include "qgsmaplayerdependency.h"

class QgsMapLayerLegend;
class QgsMapLayerRenderer;
@@ -700,20 +701,29 @@ class CORE_EXPORT QgsMapLayer : public QObject

/**
* Sets the list of layers that may modify data/geometries of this layer when modified.
* @see dataDependencies
* @see dependencies()
*
* @param layersIds IDs of the layers that this layer depends on
* @returns false if a dependency cycle has been detected (the change dependency set is not changed in that case)
*/
virtual bool setDataDependencies( const QSet<QString>& layersIds );

/**
* Gets the list of layers that may modify data/geometries of this layer when modified.
* @see setDataDependencies
* Sets the list of layers that may modify data/geometries of this layer when modified.
* @see dependencies()
*
* @param layers set of QgsMapLayerDependency. Only user-defined dependencies will be added
* @returns false if a dependency cycle has been detected (the change dependency set is not changed in that case)
*/
bool setDataDependencies( const QSet<QgsMapLayerDependency>& layers );

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@m-kuhn

m-kuhn Aug 31, 2016

Member

Can the getters and setters be named analogue?
setDependencies() / dependencies()
or
setDataDependencies() / dataDependencies()

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@mhugo

mhugo Aug 31, 2016

It is named like this on purpose ... Layers dependencies are "read only" (given by the provider) and cannot be modified by the user

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@m-kuhn

m-kuhn Aug 31, 2016

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Shouldn't there also be a getter for dataDependencies() besides dependencies() then?

So manipulation can be:

d = l.dataDependencies()
d.append(new_dependency)
l.setDataDependencies(d)

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@mhugo

mhugo Aug 31, 2016

Right, it is better, thanks !


/**
* Gets the list of dependencies. This includes data dependencies set by the user (@see setDataDependencies)
* as well as dependencies given by the provider
*
* @returns IDs of the layers that this layer depends on
* @returns a set of QgsMapLayerDependency
*/
virtual QSet<QString> dataDependencies() const;
virtual QSet<QgsMapLayerDependency> dependencies() const;

signals:

@@ -854,10 +864,10 @@ class CORE_EXPORT QgsMapLayer : public QObject
QgsError mError;

//! List of layers that may modify this layer on modification
QSet<QString> mDataDependencies;
QSet<QgsMapLayerDependency> mDataDependencies;

//! Checks whether a new set of data dependencies will introduce a cycle
bool hasDataDependencyCycle( const QSet<QString>& layersIds ) const;
bool hasDataDependencyCycle( const QSet<QgsMapLayerDependency>& layers ) const;

private:
/**
@@ -0,0 +1,85 @@

/***************************************************************************
qgsmaplayerdependency.h - description
-------------------
begin : September 2016
copyright : (C) 2016 by Hugo Mercier
email : hugo dot mercier at oslandia 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 QGSMAPLAYERDEPENDENCY_H
#define QGSMAPLAYERDEPENDENCY_H

#include <QString>

/** \ingroup core
* This class models dependencies with or between map layers.
* A dependency is defined by a layer ID, a type and an origin.
* The two combinations of type/origin that are currently supported are:
* - PresenceDependency && FromProvider: virtual layers for instance which may depend on other layers already loaded to work
* - DataDependency && FromUser: dependencies given by the user, mainly to represent database triggers
*
* @note added in QGIS 3.0
*/
class CORE_EXPORT QgsMapLayerDependency
{
public:
//! Type of dependency
enum Type
{
PresenceDependency = 1, //< The layer must be already present (in the registry) for this dependency to be resolved
DataDependency = 2 //< The layer may be invalidated by data changes on another layer
};

//! Origin of the dependency
enum Origin
{
FromProvider = 0, //< Dependency given by the provider, the user cannot change it
FromUser = 1 //< Dependency given by the user
};

//! Standard constructor
QgsMapLayerDependency( QString layerId, Type type = DataDependency, Origin origin = FromUser ) :
mType( type ),
mOrigin( origin ),
mLayerId( layerId )
{}

//! Return the dependency type
Type type() const { return mType; }

//! Return the dependency origin
Origin origin() const { return mOrigin; }

//! Return the ID of the layer this dependency depends on
QString layerId() const { return mLayerId; }

//! Comparison operator
bool operator==( const QgsMapLayerDependency& other ) const
{
return layerId() == other.layerId() && origin() == other.origin() && type() == other.type();
}
private:
Type mType;
Origin mOrigin;
QString mLayerId;
};

/**
* global qHash function for QgsMapLayerDependency, so that it can be used in a QSet
*/
inline uint qHash( const QgsMapLayerDependency& dep )
{
return qHash( dep.layerId() ) + dep.origin() + dep.type();
}

#endif
@@ -893,7 +893,7 @@ bool QgsProject::read()
QMap<QString, QgsMapLayer*> existingMaps = QgsMapLayerRegistry::instance()->mapLayers();
for ( QMap<QString, QgsMapLayer*>::iterator it = existingMaps.begin(); it != existingMaps.end(); it++ )
{
it.value()->setDataDependencies( it.value()->dataDependencies() );
it.value()->setDataDependencies( it.value()->dependencies() );
}

// read the project: used by map canvas and legend
@@ -997,7 +997,7 @@ void QgsProject::onMapLayersAdded( const QList<QgsMapLayer*>& layers )
// check if we have to update connections for layers with dependencies
for ( QMap<QString, QgsMapLayer*>::iterator it = existingMaps.begin(); it != existingMaps.end(); it++ )
{
QSet<QString> deps = it.value()->dataDependencies();
QSet<QgsMapLayerDependency> deps = it.value()->dependencies();
if ( deps.contains( layer->id() ) )
{
// reconnect to change signals

1 comment on commit 0749ba4

@m-kuhn

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@m-kuhn m-kuhn commented on 0749ba4 Aug 31, 2016

Nice feature, I'm sure I'll want to use it soon :)

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