QGIS API Documentation  3.23.0-Master (22c16f2067)
qgsmapcanvastracer.cpp
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1 /***************************************************************************
2  qgsmapcanvastracer.cpp
3  ---------------------
4  begin : January 2016
5  copyright : (C) 2016 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 #include "qgsmapcanvastracer.h"
16 
17 #include "qgsapplication.h"
18 #include "qgsmapcanvas.h"
19 #include "qgsproject.h"
20 #include "qgsmessagebar.h"
21 #include "qgsmessagebaritem.h"
22 #include "qgssnappingutils.h"
23 #include "qgsvectorlayer.h"
24 #include "qgssnappingconfig.h"
25 #include "qgssettingsregistrycore.h"
26 #include "qgsrendercontext.h"
27 
28 #include <QAction>
29 
30 #include <QGlobalStatic>
31 
32 typedef QHash<QgsMapCanvas *, QgsMapCanvasTracer *> TracerCanvasHash;
34 
36  : mCanvas( canvas )
37  , mMessageBar( messageBar )
38 
39 {
40  sTracers()->insert( canvas, this );
41 
42  // when things change we just invalidate the graph - and set up new parameters again only when necessary
47  connect( canvas, &QgsMapCanvas::currentLayerChanged, this, &QgsMapCanvasTracer::onCurrentLayerChanged );
49  connect( canvas, &QObject::destroyed, this, [this]() { mCanvas = nullptr; } );
50 
51  // arbitrarily chosen limit that should allow for fairly fast initialization
52  // of the underlying graph structure
53  setMaxFeatureCount( QgsSettingsRegistryCore::settingsDigitizingTracingMaxFeatureCount.value() );
54 }
55 
57 {
58  sTracers->remove( mCanvas );
59 }
60 
62 {
63  return sTracers->value( canvas, nullptr );
64 }
65 
67 {
68  Q_UNUSED( addingVertex )
69 
70  if ( !mMessageBar )
71  return;
72 
73  // remove previous message (if any)
74  mMessageBar->popWidget( mLastMessage );
75  mLastMessage = nullptr;
76 
77  QString message;
78  switch ( err )
79  {
80  case ErrTooManyFeatures:
81  message = tr( "Disabled - there are too many features displayed. Try zooming in or disable some layers." );
82  break;
83  case ErrNone:
84  default:
85  break;
86  }
87 
88  if ( message.isEmpty() && hasTopologyProblem() )
89  {
90  message = tr( "Tracing may not work correctly. Please check topology of the input layers." );
91  }
92 
93  if ( message.isEmpty() )
94  return;
95 
96  mLastMessage = new QgsMessageBarItem( tr( "Tracing" ), message, Qgis::MessageLevel::Warning, QgsMessageBar::defaultMessageTimeout( Qgis::MessageLevel::Info ) );
97  mMessageBar->pushItem( mLastMessage );
98 }
99 
101 {
104  setRenderContext( &ctx );
105  setExtent( mCanvas->extent() );
106 
107  QList<QgsVectorLayer *> layers;
108  const QList<QgsMapLayer *> visibleLayers = mCanvas->mapSettings().layers( true );
109 
110  switch ( mCanvas->snappingUtils()->config().mode() )
111  {
112  default:
114  {
115  QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( mCanvas->currentLayer() );
116  if ( vl && visibleLayers.contains( vl ) )
117  layers << vl;
118  }
119  break;
121  {
122  const auto constVisibleLayers = visibleLayers;
123  for ( QgsMapLayer *layer : constVisibleLayers )
124  {
125  QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( layer );
126  if ( vl )
127  layers << vl;
128  }
129  }
130  break;
132  {
133  const auto constLayers = mCanvas->snappingUtils()->layers();
134  for ( const QgsSnappingUtils::LayerConfig &cfg : constLayers )
135  {
136  if ( visibleLayers.contains( cfg.layer ) )
137  layers << cfg.layer;
138  }
139  }
140  break;
141  }
142 
143  setLayers( layers );
144 }
145 
146 void QgsMapCanvasTracer::onCurrentLayerChanged()
147 {
148  // no need to bother if we are not snapping
149  if ( mCanvas->snappingUtils()->config().mode() == QgsSnappingConfig::ActiveLayer )
150  invalidateGraph();
151 }
Extension of QgsTracer that provides extra functionality:
QgsMapCanvasTracer(QgsMapCanvas *canvas, QgsMessageBar *messageBar=nullptr)
Create tracer associated with a particular map canvas, optionally message bar for reporting.
void reportError(PathError err, bool addingVertex)
Report a path finding error to the user.
static QgsMapCanvasTracer * tracerForCanvas(QgsMapCanvas *canvas)
Retrieve instance of this class associated with given canvas (if any).
void configure() override
Sets configuration from current snapping settings and canvas settings.
Map canvas is a class for displaying all GIS data types on a canvas.
Definition: qgsmapcanvas.h:88
void extentsChanged()
Emitted when the extents of the map change.
void currentLayerChanged(QgsMapLayer *layer)
Emitted when the current layer is changed.
QgsSnappingUtils * snappingUtils() const
Returns snapping utility class that is associated with map canvas.
void destinationCrsChanged()
Emitted when map CRS has changed.
void transformContextChanged()
Emitted when the canvas transform context is changed.
void layersChanged()
Emitted when a new set of layers has been received.
const QgsMapSettings & mapSettings() const
Gets access to properties used for map rendering.
QgsRectangle extent() const
Returns the current zoom extent of the map canvas.
QgsMapLayer * currentLayer()
returns current layer (set by legend widget)
Base class for all map layer types.
Definition: qgsmaplayer.h:73
QList< QgsMapLayer * > layers(bool expandGroupLayers=false) const
Returns the list of layers which will be rendered in the map.
QgsCoordinateReferenceSystem destinationCrs() const
Returns the destination coordinate reference system for the map render.
QgsCoordinateTransformContext transformContext() const
Returns the coordinate transform context, which stores various information regarding which datum tran...
Represents an item shown within a QgsMessageBar widget.
A bar for displaying non-blocking messages to the user.
Definition: qgsmessagebar.h:61
static int defaultMessageTimeout(Qgis::MessageLevel level=Qgis::MessageLevel::NoLevel)
Returns the default timeout in seconds for timed messages of the specified level.
bool popWidget(QgsMessageBarItem *item)
Remove the specified item from the bar, and display the next most recent one in the stack.
void pushItem(QgsMessageBarItem *item)
Display a message item on the bar, after hiding the currently visible one and putting it in a stack.
Contains information about the context of a rendering operation.
static QgsRenderContext fromMapSettings(const QgsMapSettings &mapSettings)
create initialized QgsRenderContext instance from given QgsMapSettings
@ ActiveLayer
On the active layer.
@ AdvancedConfiguration
On a per layer configuration basis.
@ AllLayers
On all vector layers.
SnappingMode mode() const
Returns the mode (all layers, active layer, per layer settings)
QList< QgsSnappingUtils::LayerConfig > layers() const
Query layers used for snapping.
void configChanged(const QgsSnappingConfig &snappingConfig)
Emitted when the snapping settings object changes.
QgsSnappingConfig config
void setMaxFeatureCount(int count)
Gets maximum possible number of features in graph. If the number is exceeded, graph is not created.
Definition: qgstracer.h:116
void setRenderContext(const QgsRenderContext *renderContext)
Sets the renderContext used for tracing only on visible features.
Definition: qgstracer.cpp:641
bool hasTopologyProblem() const
Whether there was an error during graph creation due to noding exception, indicating some input data ...
Definition: qgstracer.h:134
void setExtent(const QgsRectangle &extent)
Sets extent to which graph's features will be limited (empty extent means no limit)
Definition: qgstracer.cpp:647
PathError
Possible errors that may happen when calling findShortestPath()
Definition: qgstracer.h:138
@ ErrNone
No error.
Definition: qgstracer.h:139
@ ErrTooManyFeatures
Max feature count threshold was reached while reading features.
Definition: qgstracer.h:140
void setLayers(const QList< QgsVectorLayer * > &layers)
Sets layers used for tracing.
Definition: qgstracer.cpp:602
QList< QgsVectorLayer * > layers() const
Gets layers used for tracing.
Definition: qgstracer.h:56
void invalidateGraph()
Destroy the existing graph structure if any (de-initialize)
Definition: qgstracer.cpp:687
void setDestinationCrs(const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context)
Sets the crs and transform context used for tracing.
Definition: qgstracer.cpp:634
Represents a vector layer which manages a vector based data sets.
QHash< QgsMapCanvas *, QgsMapCanvasTracer * > TracerCanvasHash
Q_GLOBAL_STATIC(TracerCanvasHash, sTracers)
Configures how a certain layer should be handled in a snapping operation.