[tracer] Fix issues with rubber bands

qgis · Jan 10, 2016 · 70c5fe5 · 70c5fe5
1 parent bbe3598
commit 70c5fe5
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Showing 4 changed files with 79 additions and 28 deletions.
diff --git a/src/core/qgstracer.cpp b/src/core/qgstracer.cpp
@@ -265,7 +265,7 @@ int point2vertex( const QgsTracerGraph& g, const QgsPoint& pt )
 }
 
 
-int point2edge( const QgsTracerGraph& g, const QgsPoint& pt, int& lineVertexAfter, double epsilon )
+int point2edge( const QgsTracerGraph& g, const QgsPoint& pt, int& lineVertexAfter, double epsilon = 1e-6 )
 {
   int vertexAfter;
 
@@ -305,11 +305,9 @@ void split_linestring( const QgsPolyline& points, const QgsPoint& pt, int lineVe
 
 int join_vertex_to_graph( QgsTracerGraph& g, const QgsPoint& pt )
 {
-  const double epsilon = 1e-6;
-
   // find edge where the point is
   int lineVertexAfter;
-  int eIdx = point2edge( g, pt, lineVertexAfter, epsilon );
+  int eIdx = point2edge( g, pt, lineVertexAfter );
 
   //qDebug("e: %d", eIdx);
 
@@ -625,3 +623,15 @@ QVector<QgsPoint> QgsTracer::findShortestPath( const QgsPoint& p1, const QgsPoin
 
   return points;
 }
+
+bool QgsTracer::isPointSnapped( const QgsPoint& pt )
+{
+  init();  // does nothing if the graph exists already
+
+  if ( point2vertex( *mGraph, pt ) != -1 )
+    return true;
+
+  int lineVertexAfter;
+  int e = point2edge( *mGraph, pt, lineVertexAfter );
+  return e != -1;
+}
diff --git a/src/core/qgstracer.h b/src/core/qgstracer.h
@@ -63,6 +63,9 @@ class CORE_EXPORT QgsTracer : public QObject
     //! if the two points are not connected.
     QVector<QgsPoint> findShortestPath( const QgsPoint& p1, const QgsPoint& p2 );
 
+    //! Find out whether the point is snapped to a vertex or edge (i.e. it can be used for tracing start/stop)
+    bool isPointSnapped( const QgsPoint& pt );
+
   private:
     void initGraph();
     void invalidateGraph();

diff --git a/src/gui/qgsmaptoolcapture.cpp b/src/gui/qgsmaptoolcapture.cpp
@@ -148,47 +148,70 @@ void QgsMapToolCapture::tracingMouseMove( QgsMapMouseEvent* e )
   if ( !e->isSnapped() )
     return;
 
-  QgsPointV2 v;
-  QgsVertexId::VertexType vt;
-  mCaptureCurve.pointAt( mCaptureCurve.numPoints() - 1, v, vt );
+  QgsPointV2 v = mCaptureCurve.endPoint();
 
   QgsMapCanvasTracer* tracer = QgsMapCanvasTracer::tracerForCanvas( mCanvas );
   if ( !tracer )
     return;  // this should not happen!
 
+  mTempRubberBand->reset( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line );
+
   QVector<QgsPoint> points = tracer->findShortestPath( QgsPoint( v.x(), v.y() ), e->mapPoint() );
   if ( points.isEmpty() )
     return;
 
+  if ( mCaptureMode == CapturePolygon )
+    mTempRubberBand->addPoint( *mRubberBand->getPoint( 0, 0 ), false );
+
   //  update rubberband
-  mTempRubberBand->reset( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line );
   for ( int i = 0; i < points.count(); ++i )
     mTempRubberBand->addPoint( points.at( i ), i == points.count() - 1 );
 }
 
 
-void QgsMapToolCapture::tracingAddVertex( const QgsPoint& point )
+bool QgsMapToolCapture::tracingAddVertex( const QgsPoint& point )
 {
   QgsMapCanvasTracer* tracer = QgsMapCanvasTracer::tracerForCanvas( mCanvas );
   if ( !tracer )
-    return;  // this should not happen!
+    return false;  // this should not happen!
 
-  QgsPointV2 v;
-  QgsVertexId::VertexType vt;
-  mCaptureCurve.pointAt( mCaptureCurve.numPoints() - 1, v, vt );
+  if ( mCaptureCurve.numPoints() == 0 )
+  {
+    // only accept first point if it is snapped to the graph (to vertex or edge)
+    bool res = tracer->isPointSnapped( point );
+    if ( res )
+    {
+      QgsPoint layerPoint;
+      nextPoint( point, layerPoint ); // assuming the transform went fine earlier
+
+      mRubberBand->addPoint( point );
+      mCaptureCurve.addVertex( QgsPointV2( layerPoint.x(), layerPoint.y() ) );
+    }
+    return res;
+  }
+
+  QgsPointV2 v = mCaptureCurve.endPoint();
 
   QVector<QgsPoint> points = tracer->findShortestPath( QgsPoint( v.x(), v.y() ), point );
   if ( points.isEmpty() )
-    return; // ignore the vertex - can't find path to the end point!
+    return false; // ignore the vertex - can't find path to the end point!
 
+  // transform points
+  QList<QgsPointV2> layerPoints;
   QgsPoint lp; // in layer coords
   for ( int i = 1; i < points.count(); ++i )
   {
     if ( nextPoint( points[i], lp ) != 0 )
-      continue; // TODO: should completely abort
+      return false;
+    layerPoints << QgsPointV2( lp.x(), lp.y() );
+  }
+
+  for ( int i = 1; i < points.count(); ++i )
+  {
     mRubberBand->addPoint( points[i], i == points.count() - 1 );
-    mCaptureCurve.addVertex( QgsPointV2( lp.x(), lp.y() ) );
+    mCaptureCurve.addVertex( layerPoints[i-1] );
   }
+  return true;
 }
 
 
@@ -232,7 +255,20 @@ void QgsMapToolCapture::cadCanvasMoveEvent( QgsMapMouseEvent * e )
     }
     else
     {
-      mTempRubberBand->movePoint( point );
+      if ( mCaptureCurve.numPoints() > 0 &&
+           (( mCaptureMode == CaptureLine && mTempRubberBand->numberOfVertices() != 2 ) ||
+            ( mCaptureMode == CapturePolygon && mTempRubberBand->numberOfVertices() != 3 ) ) )
+      {
+        // fix temporary rubber band after tracing which may have added multiple points
+        mTempRubberBand->reset( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line );
+        if ( mCaptureMode == CapturePolygon )
+          mTempRubberBand->addPoint( *mRubberBand->getPoint( 0, 0 ), false );
+        QgsPointV2 pt = mCaptureCurve.endPoint();
+        mTempRubberBand->addPoint( QgsPoint( pt.x(), pt.y() ) );
+        mTempRubberBand->addPoint( point );
+      }
+      else
+        mTempRubberBand->movePoint( point );
     }
   }
 } // mouseMoveEvent
@@ -287,26 +323,28 @@ int QgsMapToolCapture::addVertex( const QgsPoint& point )
     mRubberBand = createRubberBand( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line );
   }
 
-  if ( tracingEnabled() && mCaptureCurve.numPoints() != 0 )
+  if ( !mTempRubberBand )
   {
-    tracingAddVertex( point );
+    mTempRubberBand = createRubberBand( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line, true );
   }
   else
   {
-    // ordinary digitizing
-    mRubberBand->addPoint( point );
-    mCaptureCurve.addVertex( QgsPointV2( layerPoint.x(), layerPoint.y() ) );
+    mTempRubberBand->reset( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line );
   }
 
-  // re-initialize temporary rubber band for further digitizing
-
-  if ( !mTempRubberBand )
+  if ( tracingEnabled() )
   {
-    mTempRubberBand = createRubberBand( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line, true );
+    if ( !tracingAddVertex( point ) )
+    {
+      emit messageEmitted( tr( "Tracing: The point needs to be snapped to a geometry" ), QgsMessageBar::WARNING );
+      return 1;  // early exit if the point cannot be accepted
+    }
   }
   else
   {
-    mTempRubberBand->reset( mCaptureMode == CapturePolygon ? QGis::Polygon : QGis::Line );
+    // ordinary digitizing
+    mRubberBand->addPoint( point );
+    mCaptureCurve.addVertex( QgsPointV2( layerPoint.x(), layerPoint.y() ) );
   }
 
   if ( mCaptureMode == CaptureLine )

diff --git a/src/gui/qgsmaptoolcapture.h b/src/gui/qgsmaptoolcapture.h
@@ -146,7 +146,7 @@ class GUI_EXPORT QgsMapToolCapture : public QgsMapToolAdvancedDigitizing
     //! handle of mouse movement when tracing enabled and capturing has started
     void tracingMouseMove( QgsMapMouseEvent* e );
     //! handle of addition of clicked point (with the rest of the trace) when tracing enabled
-    void tracingAddVertex( const QgsPoint& point );
+    bool tracingAddVertex( const QgsPoint& point );
 
   private:
     /** Flag to indicate a map canvas capture operation is taking place */