QGIS API Documentation 3.27.0-Master (9c08adf5ef)
qgsmaplayerref.h
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1/***************************************************************************
2 qgsmaplayerref.h
3 --------------------------------------
4 Date : January 2017
5 Copyright : (C) 2017 by Martin Dobias
6 Email : wonder dot sk at gmail dot com
7 ***************************************************************************
8 * *
9 * This program is free software; you can redistribute it and/or modify *
10 * it under the terms of the GNU General Public License as published by *
11 * the Free Software Foundation; either version 2 of the License, or *
12 * (at your option) any later version. *
13 * *
14 ***************************************************************************/
15
16#ifndef QGSMAPLAYERREF_H
17#define QGSMAPLAYERREF_H
18
19#define SIP_NO_FILE
20
21#include <QPointer>
22
23#include "qgsmaplayer.h"
24#include "qgsdataprovider.h"
25#include "qgsproject.h"
26#include <utility>
27
33template<typename TYPE>
35{
36
42 {
43 Name = 1 << 2,
44 Provider = 1 << 3,
45 Source = 1 << 4,
47 };
48
49
55 _LayerRef( TYPE *l = nullptr )
56 : layer( l )
57 , layerId( l ? l->id() : QString() )
58 , source( l ? l->publicSource() : QString() )
59 , name( l ? l->name() : QString() )
60 , provider( l && l->dataProvider() ? l->dataProvider()->name() : QString() )
61 {}
62
67 _LayerRef( const QString &id, const QString &name = QString(), const QString &source = QString(), const QString &provider = QString() )
68 : layer()
69 , layerId( id )
70 , source( source )
71 , name( name )
73 {}
74
78 void setLayer( TYPE *l )
79 {
80 layer = l;
81 layerId = l ? l->id() : QString();
82 source = l ? l->publicSource() : QString();
83 name = l ? l->name() : QString();
84 provider = l && l->dataProvider() ? l->dataProvider()->name() : QString();
85 }
86
91 operator bool() const
92 {
93 return static_cast< bool >( layer.data() );
94 }
95
99 TYPE *operator->() const
100 {
101 return layer.data();
102 }
103
108 TYPE *get() const
109 {
110 return layer.data();
111 }
112
114 QPointer<TYPE> layer;
115
117 QString layerId;
118
120 QString source;
122 QString name;
124 QString provider;
125
132 {
133 if ( layer->publicSource() != source ||
134 layer->name() != name )
135 return false;
136
137 if ( layer->providerType() != provider )
138 return false;
139
140 return true;
141 }
142
150 TYPE *resolve( const QgsProject *project )
151 {
152 if ( project && !layerId.isEmpty() )
153 {
154 if ( TYPE *l = qobject_cast<TYPE *>( project->mapLayer( layerId ) ) )
155 {
156 setLayer( l );
157 return l;
158 }
159 }
160 return nullptr;
161 }
162
163 bool layerMatchesWeakly( QgsMapLayer *layer, MatchType matchType = MatchType::All ) const
164 {
165 // First match the name
166 if ( matchType & MatchType::Name && ( layer->name().isEmpty() || layer->name() != name ) )
167 {
168 return false;
169 }
170 else
171 {
172 // We have found a match by name, now check the other
173 // criteria
174 if ( matchType & MatchType::Provider && layer->providerType() != provider )
175 {
176 return false;
177 }
178 if ( matchType & MatchType::Source && layer->publicSource() != source )
179 {
180 return false;
181 }
182 // All tests passed
183 return true;
184 }
185 }
186
211 TYPE *resolveWeakly( const QgsProject *project, MatchType matchType = MatchType::All )
212 {
213 // first try matching by layer ID
214 if ( resolve( project ) )
215 return layer;
216
217 if ( project )
218 {
219 QList<QgsMapLayer *> layers;
220 // If matching by name ...
221 if ( matchType & MatchType::Name )
222 {
223 if ( name.isEmpty() )
224 {
225 return nullptr;
226 }
227 layers = project->mapLayersByName( name );
228 }
229 else // ... we need all layers
230 {
231 layers = project->mapLayers().values();
232 }
233 for ( auto it = layers.constBegin(); it != layers.constEnd(); ++it )
234 {
235 if ( TYPE *tl = qobject_cast< TYPE *>( *it ) )
236 {
237 if ( layerMatchesWeakly( tl, matchType ) )
238 {
239 setLayer( tl );
240 return tl;
241 }
242 }
243 }
244 }
245 return nullptr;
246 }
247
270 TYPE *resolveByIdOrNameOnly( const QgsProject *project )
271 {
272 // first try by matching by layer ID, or weakly by source, name and provider
273 if ( resolveWeakly( project ) )
274 return layer;
275
276 // fallback to checking by name only
277 if ( project && !name.isEmpty() )
278 {
279 const QList<QgsMapLayer *> layers = project->mapLayersByName( name );
280 for ( QgsMapLayer *l : layers )
281 {
282 if ( TYPE *tl = qobject_cast< TYPE *>( l ) )
283 {
284 setLayer( tl );
285 return tl;
286 }
287 }
288 }
289 return nullptr;
290 }
291
292
293};
294
296
297#endif // QGSMAPLAYERREF_H
Base class for all map layer types.
Definition: qgsmaplayer.h:73
Encapsulates a QGIS project, including sets of map layers and their styles, layouts,...
Definition: qgsproject.h:104
Q_INVOKABLE QgsMapLayer * mapLayer(const QString &layerId) const
Retrieve a pointer to a registered layer by layer ID.
QList< QgsMapLayer * > mapLayersByName(const QString &layerName) const
Retrieve a list of matching registered layers by layer name.
QMap< QString, QgsMapLayer * > mapLayers(const bool validOnly=false) const
Returns a map of all registered layers by layer ID.
_LayerRef< QgsMapLayer > QgsMapLayerRef
Internal structure to keep weak pointer to QgsMapLayer or layerId if the layer is not available yet.
TYPE * operator->() const
Forwards the to map layer.
TYPE * resolveWeakly(const QgsProject *project, MatchType matchType=MatchType::All)
Resolves the map layer by attempting to find a matching layer in a project using a weak match.
_LayerRef(const QString &id, const QString &name=QString(), const QString &source=QString(), const QString &provider=QString())
Constructor for a weak layer reference, using a combination of layer ID, name, public source and prov...
_LayerRef(TYPE *l=nullptr)
Constructor for a layer reference from an existing map layer.
MatchType
Flag for match type in weak resolution.
@ All
Match layer source.
@ Provider
Match layer name.
@ Source
Match layer provider name.
QString source
Weak reference to layer public source.
QString name
Weak reference to layer name.
bool layerMatchesWeakly(QgsMapLayer *layer, MatchType matchType=MatchType::All) const
TYPE * resolveByIdOrNameOnly(const QgsProject *project)
Resolves the map layer by attempting to find a matching layer in a project using a weak match.
TYPE * get() const
Returns a pointer to the layer, or nullptr if the reference has not yet been matched to a layer.
QString provider
Weak reference to layer provider.
bool layerMatchesSource(QgsMapLayer *layer) const
Returns true if a layer matches the weak references to layer public source, layer name and data provi...
QPointer< TYPE > layer
Weak pointer to map layer.
TYPE * resolve(const QgsProject *project)
Resolves the map layer by attempting to find a layer with matching ID within a project.
void setLayer(TYPE *l)
Sets the reference to point to a specified layer.
QString layerId
Original layer ID.