Merge pull request #5195 from wonder-sk/tracing-with-offset

Tracing with offset

Author: wonder-sk

python/core/qgstracer.sip

@@ -60,6 +60,33 @@ Get extent to which graph's features will be limited (empty extent means no limi
     void setExtent( const QgsRectangle &extent );
 %Docstring
 Set extent to which graph's features will be limited (empty extent means no limit)
+%End
+
+    double offset() const;
+%Docstring
+ Get offset in map units that should be applied to the traced paths returned from findShortestPath().
+ Positive offset for right side, negative offset for left side.
+.. versionadded:: 3.0
+ :rtype: float
+%End
+
+    void setOffset( double offset );
+%Docstring
+ Set offset in map units that should be applied to the traced paths returned from findShortestPath().
+ Positive offset for right side, negative offset for left side.
+.. versionadded:: 3.0
+%End
+
+    void offsetParameters( int &quadSegments /Out/, int &joinStyle /Out/, double &miterLimit /Out/ );
+%Docstring
+ Get extra parameters for offset curve algorithm (used when offset is non-zero)
+.. versionadded:: 3.0
+%End
+
+    void setOffsetParameters( int quadSegments, int joinStyle, double miterLimit );
+%Docstring
+ Set extra parameters for offset curve algorithm (used when offset is non-zero)
+.. versionadded:: 3.0
 %End
 
     int maxFeatureCount() const;

python/gui/qgsmaptooladvanceddigitizing.sip

@@ -108,6 +108,8 @@ Catch the mouse move event, filters it, transforms it to map coordinates and sen
 .. versionadded:: 3.0
 %End
 
+  public:
+
     virtual void cadCanvasPressEvent( QgsMapMouseEvent *e );
 %Docstring
  Override this method when subclassing this class.

src/app/qgisapp.cpp

@@ -1246,6 +1246,7 @@ QgisApp::QgisApp()
   mLayerTreeView = new QgsLayerTreeView( this );
   mUndoWidget = new QgsUndoWidget( nullptr, mMapCanvas );
   mInfoBar = new QgsMessageBar( centralWidget() );
+  mAdvancedDigitizingDockWidget = new QgsAdvancedDigitizingDockWidget( mMapCanvas, this );
   // More tests may need more members to be initialized
 }
 
@@ -2285,6 +2286,8 @@ void QgisApp::createToolBars()
 
   mTracer = new QgsMapCanvasTracer( mMapCanvas, messageBar() );
   mTracer->setActionEnableTracing( mSnappingWidget->enableTracingAction() );
+  connect( mSnappingWidget->tracingOffsetSpinBox(), static_cast< void ( QgsDoubleSpinBox::* )( double ) >( &QgsDoubleSpinBox::valueChanged ),
+  this, [ = ]( double v ) { mTracer->setOffset( v ); } );
 
   QList<QAction *> toolbarMenuActions;
   // Set action names so that they can be used in customization

src/app/qgssnappingwidget.cpp

@@ -16,15 +16,17 @@
 
 #include <QAction>
 #include <QComboBox>
-#include <QDoubleSpinBox>
 #include <QFont>
 #include <QHBoxLayout>
 #include <QHeaderView>
+#include <QLabel>
 #include <QMenu>
 #include <QToolBar>
 #include <QToolButton>
+#include <QWidgetAction>
 
 #include "qgsapplication.h"
+#include "qgsdoublespinbox.h"
 #include "qgslayertreegroup.h"
 #include "qgslayertree.h"
 #include "qgslayertreeview.h"
@@ -148,6 +150,22 @@ QgsSnappingWidget::QgsSnappingWidget( QgsProject *project, QgsMapCanvas *canvas,
   mEnableTracingAction->setShortcut( tr( "T", "Enable Tracing" ) );
   mEnableTracingAction->setObjectName( QStringLiteral( "EnableTracingAction" ) );
 
+  mTracingOffsetSpinBox = new QgsDoubleSpinBox;
+  mTracingOffsetSpinBox->setRange( -1000000, 1000000 );
+  mTracingOffsetSpinBox->setDecimals( 6 );
+  mTracingOffsetSpinBox->setClearValue( 0 );
+  mTracingOffsetSpinBox->setClearValueMode( QgsDoubleSpinBox::CustomValue );
+  QMenu *tracingMenu = new QMenu( this );
+  QWidgetAction *widgetAction = new QWidgetAction( tracingMenu );
+  QVBoxLayout *tracingWidgetLayout = new QVBoxLayout;
+  tracingWidgetLayout->addWidget( new QLabel( "Offset" ) );
+  tracingWidgetLayout->addWidget( mTracingOffsetSpinBox );
+  QWidget *tracingWidget = new QWidget;
+  tracingWidget->setLayout( tracingWidgetLayout );
+  widgetAction->setDefaultWidget( tracingWidget );
+  tracingMenu->addAction( widgetAction );
+  mEnableTracingAction->setMenu( tracingMenu );
+
   // layout
   if ( mDisplayMode == ToolBar )
   {

src/app/qgssnappingwidget.h

@@ -24,6 +24,7 @@ class QFont;
 class QToolButton;
 class QTreeView;
 
+class QgsDoubleSpinBox;
 class QgsLayerTreeGroup;
 class QgsLayerTreeNode;
 class QgsLayerTreeView;
@@ -74,6 +75,9 @@ class APP_EXPORT QgsSnappingWidget : public QWidget
      */
     QAction *enableTracingAction() { return mEnableTracingAction; }
 
+    //! Returns spin box used to set offset for tracing
+    QgsDoubleSpinBox *tracingOffsetSpinBox() { return mTracingOffsetSpinBox; }
+
   signals:
     void snappingConfigChanged();
 
@@ -136,6 +140,7 @@ class APP_EXPORT QgsSnappingWidget : public QWidget
     QAction *mTopologicalEditingAction = nullptr;
     QAction *mIntersectionSnappingAction = nullptr;
     QAction *mEnableTracingAction = nullptr;
+    QgsDoubleSpinBox *mTracingOffsetSpinBox = nullptr;
     QTreeView *mLayerTreeView = nullptr;
 
     void cleanGroup( QgsLayerTreeNode *node );

src/core/qgstracer.cpp

@@ -615,6 +615,25 @@ void QgsTracer::setExtent( const QgsRectangle &extent )
   invalidateGraph();
 }
 
+void QgsTracer::setOffset( double offset )
+{
+  mOffset = offset;
+}
+
+void QgsTracer::offsetParameters( int &quadSegments, int &joinStyle, double &miterLimit )
+{
+  quadSegments = mOffsetSegments;
+  joinStyle = mOffsetJoinStyle;
+  miterLimit = mOffsetMiterLimit;
+}
+
+void QgsTracer::setOffsetParameters( int quadSegments, int joinStyle, double miterLimit )
+{
+  mOffsetSegments = quadSegments;
+  mOffsetJoinStyle = joinStyle;
+  mOffsetMiterLimit = miterLimit;
+}
+
 bool QgsTracer::init()
 {
   if ( mGraph )
@@ -695,6 +714,30 @@ QVector<QgsPointXY> QgsTracer::findShortestPath( const QgsPointXY &p1, const Qgs
 
   resetGraph( *mGraph );
 
+  if ( !points.isEmpty() && mOffset != 0 )
+  {
+    QList<QgsPointXY> pointsInput( points.toList() );
+    QgsLineString linestring( pointsInput );
+    std::unique_ptr<QgsGeometryEngine> linestringEngine( QgsGeometry::createGeometryEngine( &linestring ) );
+    std::unique_ptr<QgsAbstractGeometry> linestringOffset( linestringEngine->offsetCurve( mOffset, mOffsetSegments, mOffsetJoinStyle, mOffsetMiterLimit ) );
+    if ( QgsLineString *ls2 = qgsgeometry_cast<QgsLineString *>( linestringOffset.get() ) )
+    {
+      points.clear();
+      for ( int i = 0; i < ls2->numPoints(); ++i )
+        points << QgsPointXY( ls2->pointN( i ) );
+
+      // sometimes (with negative offset?) the resulting curve is reversed
+      if ( points.count() >= 2 )
+      {
+        QgsPointXY res1 = points.first(), res2 = points.last();
+        double diffNormal = res1.distance( p1 ) + res2.distance( p2 );
+        double diffReversed = res1.distance( p2 ) + res2.distance( p1 );
+        if ( diffReversed < diffNormal )
+          std::reverse( points.begin(), points.end() );
+      }
+    }
+  }
+
   if ( error )
     *error = points.isEmpty() ? ErrNoPath : ErrNone;
 

src/core/qgstracer.h

@@ -63,6 +63,32 @@ class CORE_EXPORT QgsTracer : public QObject
     //! Set extent to which graph's features will be limited (empty extent means no limit)
     void setExtent( const QgsRectangle &extent );
 
+    /**
+     * Get offset in map units that should be applied to the traced paths returned from findShortestPath().
+     * Positive offset for right side, negative offset for left side.
+     * \since QGIS 3.0
+     */
+    double offset() const { return mOffset; }
+
+    /**
+     * Set offset in map units that should be applied to the traced paths returned from findShortestPath().
+     * Positive offset for right side, negative offset for left side.
+     * \since QGIS 3.0
+     */
+    void setOffset( double offset );
+
+    /**
+     * Get extra parameters for offset curve algorithm (used when offset is non-zero)
+     * \since QGIS 3.0
+     */
+    void offsetParameters( int &quadSegments SIP_OUT, int &joinStyle SIP_OUT, double &miterLimit SIP_OUT );
+
+    /**
+     * Set extra parameters for offset curve algorithm (used when offset is non-zero)
+     * \since QGIS 3.0
+     */
+    void setOffsetParameters( int quadSegments, int joinStyle, double miterLimit );
+
     //! Get maximum possible number of features in graph. If the number is exceeded, graph is not created.
     int maxFeatureCount() const { return mMaxFeatureCount; }
     //! Get maximum possible number of features in graph. If the number is exceeded, graph is not created.
@@ -138,6 +164,15 @@ class CORE_EXPORT QgsTracer : public QObject
     //! Extent for graph building (empty extent means no limit)
     QgsRectangle mExtent;
 
+    //! Offset in map units that should be applied to the traced paths
+    double mOffset = 0;
+    //! Offset parameter: Number of segments (approximation of circle quarter) when using round join style
+    int mOffsetSegments = 8;
+    //! Offset parameter: Join style (1 = round, 2 = miter, 3 = bevel)
+    int mOffsetJoinStyle = 2;
+    //! Offset parameter: Limit for miter join style
+    double mOffsetMiterLimit = 5.;
+
     /**
      * Limit of how many features can be in the graph (0 means no limit).
      * This is to avoid possibly long graph preparation for complicated layers

src/gui/qgsmaptooladvanceddigitizing.h

@@ -106,6 +106,8 @@ class GUI_EXPORT QgsMapToolAdvancedDigitizing : public QgsMapToolEdit
      */
     void setAutoSnapEnabled( bool enabled ) { mAutoSnapEnabled = enabled; }
 
+  public:
+
     /**
      * Override this method when subclassing this class.
      * This will receive adapted events from the cad system whenever a

src/gui/qgsmaptoolcapture.cpp

@@ -142,6 +142,12 @@ QgsPointXY QgsMapToolCapture::tracingStartPoint()
     QgsMapLayer *layer = mCanvas->currentLayer();
     if ( !layer )
       return QgsPointXY();
+
+    // if we have starting point from previous trace, then preferably use that one
+    // (useful when tracing with offset)
+    if ( mTracingStartPoint != QgsPointXY() )
+      return mTracingStartPoint;
+
     QgsPoint v = mCaptureCurve.endPoint();
     return toMapCoordinates( layer, QgsPointXY( v.x(), v.y() ) );
   }
@@ -179,6 +185,26 @@ bool QgsMapToolCapture::tracingMouseMove( QgsMapMouseEvent *e )
   if ( mCaptureMode == CapturePolygon )
     mTempRubberBand->addPoint( *mRubberBand->getPoint( 0, 0 ), false );
 
+  // if there is offset, we need to fix the rubber bands to make sure they are aligned correctly.
+  // There are two cases we need to sort out:
+  // 1. the last point of mRubberBand may need to be moved off the traced curve to respect the offset
+  // 2. extra first point of mTempRubberBand may be needed if there is gap between where mRubberBand ends and trace starts
+  if ( mRubberBand->numberOfVertices() != 0 )
+  {
+    QgsPointXY lastPoint = *mRubberBand->getPoint( 0, mRubberBand->numberOfVertices() - 1 );
+    if ( lastPoint == pt0 && points[0] != lastPoint )
+    {
+      // if rubber band had just one point, for some strange reason it contains the point twice
+      // we only want to move the last point if there are multiple points already
+      if ( mRubberBand->numberOfVertices() > 2 || ( mRubberBand->numberOfVertices() == 2 && *mRubberBand->getPoint( 0, 0 ) != *mRubberBand->getPoint( 0, 1 ) ) )
+        mRubberBand->movePoint( points[0] );
+    }
+    else
+    {
+      mTempRubberBand->addPoint( lastPoint, false );
+    }
+  }
+
   //  update rubberband
   for ( int i = 0; i < points.count(); ++i )
     mTempRubberBand->addPoint( points.at( i ), i == points.count() - 1 );
@@ -225,22 +251,53 @@ bool QgsMapToolCapture::tracingAddVertex( const QgsPointXY &point )
   if ( points.isEmpty() )
     return false; // ignore the vertex - can't find path to the end point!
 
+  if ( !mCaptureCurve.isEmpty() )
+  {
+    QgsPoint lp; // in layer coords
+    if ( nextPoint( QgsPoint( pt0 ), lp ) != 0 )
+      return false;
+    QgsPoint last;
+    QgsVertexId::VertexType type;
+    mCaptureCurve.pointAt( mCaptureCurve.numPoints() - 1, last, type );
+    if ( last == lp )
+    {
+      // remove the last point in the curve if it is the same as our first point
+      if ( mCaptureCurve.numPoints() != 2 )
+        mCaptureCurve.deleteVertex( QgsVertexId( 0, 0, mCaptureCurve.numPoints() - 1 ) );
+      else
+      {
+        // there is a strange behavior in deleteVertex() that with just two points
+        // the whole curve is cleared - so we need to do this little dance to work it around
+        QgsPoint first = mCaptureCurve.startPoint();
+        mCaptureCurve.clear();
+        mCaptureCurve.addVertex( first );
+      }
+      // for unknown reasons, rubber band has 2 points even if only one point has been added - handle that case
+      if ( mRubberBand->numberOfVertices() == 2 && *mRubberBand->getPoint( 0, 0 ) == *mRubberBand->getPoint( 0, 1 ) )
+        mRubberBand->removeLastPoint();
+      mRubberBand->removeLastPoint();
+      mSnappingMatches.removeLast();
+    }
+  }
+
   // transform points
   QgsPointSequence layerPoints;
   QgsPoint lp; // in layer coords
-  for ( int i = 1; i < points.count(); ++i )
+  for ( int i = 0; i < points.count(); ++i )
   {
     if ( nextPoint( QgsPoint( points[i] ), lp ) != 0 )
       return false;
     layerPoints << lp;
   }
 
-  for ( int i = 1; i < points.count(); ++i )
+  for ( int i = 0; i < points.count(); ++i )
   {
-    if ( points[i] == points[i - 1] )
+    if ( i == 0 && !mCaptureCurve.isEmpty() && mCaptureCurve.endPoint() == layerPoints[0] )
+      continue;  // avoid duplicate of the first vertex
+    if ( i > 0 && points[i] == points[i - 1] )
       continue; // avoid duplicate vertices if there are any
     mRubberBand->addPoint( points[i], i == points.count() - 1 );
-    mCaptureCurve.addVertex( layerPoints[i - 1] );
+    mCaptureCurve.addVertex( layerPoints[i] );
     mSnappingMatches.append( QgsPointLocator::Match() );
   }
 
@@ -291,9 +348,7 @@ void QgsMapToolCapture::cadCanvasMoveEvent( QgsMapMouseEvent *e )
 
     if ( !hasTrace )
     {
-      if ( mCaptureCurve.numPoints() > 0 &&
-           ( ( mCaptureMode == CaptureLine && mTempRubberBand->numberOfVertices() != 2 ) ||
-             ( mCaptureMode == CapturePolygon && mTempRubberBand->numberOfVertices() != 3 ) ) )
+      if ( mCaptureCurve.numPoints() > 0 )
       {
         // fix temporary rubber band after tracing which may have added multiple points
         mTempRubberBand->reset( mCaptureMode == CapturePolygon ? QgsWkbTypes::PolygonGeometry : QgsWkbTypes::LineGeometry );
@@ -303,6 +358,10 @@ void QgsMapToolCapture::cadCanvasMoveEvent( QgsMapMouseEvent *e )
         QgsPointXY mapPt = toMapCoordinates( qobject_cast<QgsVectorLayer *>( mCanvas->currentLayer() ), QgsPointXY( pt.x(), pt.y() ) );
         mTempRubberBand->addPoint( mapPt );
         mTempRubberBand->addPoint( point );
+
+        // fix existing rubber band after tracing - the last point may have been moved if using offset
+        if ( mRubberBand->numberOfVertices() )
+          mRubberBand->movePoint( mapPt );
       }
       else
         mTempRubberBand->movePoint( point );
@@ -419,6 +478,10 @@ int QgsMapToolCapture::addVertex( const QgsPointXY &point, const QgsPointLocator
     traceCreated = tracingAddVertex( point );
   }
 
+  // keep new tracing start point if we created a trace. This is useful when tracing with
+  // offset so that the user stays "snapped"
+  mTracingStartPoint = traceCreated ? point : QgsPointXY();
+
   if ( !traceCreated )
   {
     // ordinary digitizing
@@ -499,6 +562,8 @@ QList<QgsPointLocator::Match> QgsMapToolCapture::snappingMatches() const
 
 void QgsMapToolCapture::undo()
 {
+  mTracingStartPoint = QgsPointXY();
+
   if ( mRubberBand )
   {
     int rubberBandSize = mRubberBand->numberOfVertices();
@@ -585,6 +650,8 @@ void QgsMapToolCapture::stopCapturing()
 
   mGeomErrors.clear();
 
+  mTracingStartPoint = QgsPointXY();
+
 #ifdef Q_OS_WIN
   Q_FOREACH ( QWidget *w, qApp->topLevelWidgets() )
   {