snap to first point of new line

rblazek · rblazek · commit aa87d5cb9c15 · 2006-05-11T09:00:33.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@5437 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/plugins/grass/qgsgrassedit.cpp b/src/plugins/grass/qgsgrassedit.cpp
@@ -1140,6 +1140,49 @@ void QgsGrassEdit::snap (  QgsPoint & point )
   point.setY(y);
 }
 
+void QgsGrassEdit::snap (  QgsPoint & point, double startX, double startY )
+{
+  double x = point.x();
+  double y = point.y();
+
+  double thresh = threshold();
+
+  // Start
+  double startDist = hypot ( x-startX, y-startY);
+  bool startIn = false;
+  if ( startDist <= thresh ) startIn = true;
+
+  // Nearest node
+  double nodeX, nodeY;     
+  double nodeDist;
+  bool nodeIn = false;
+  int node = mProvider->findNode ( x, y, thresh );
+
+  if ( node > 0 ) 
+  {
+       mProvider->nodeCoor ( node, &nodeX, &nodeY );
+       nodeDist = hypot ( x-nodeX, y-nodeY);
+       nodeIn = true;
+  }
+  std::cerr << "startIn = " << startIn << std::endl;
+  std::cerr << "nodeIn = " << nodeIn << std::endl;
+  std::cerr << "startDist = " << startDist << std::endl;
+  std::cerr << "nodeDist = " << nodeDist << std::endl;
+
+  // Choose
+  if ( (startIn && !nodeIn) || (startIn && nodeIn && startDist < nodeDist)  ) 
+  {
+      x = startX; y = startY;
+  }
+  else if ( (!startIn && nodeIn) || (startIn && nodeIn && startDist > nodeDist) ) 
+  {
+      x = nodeX; y = nodeY;
+  } 
+
+  point.setX(x);
+  point.setY(y);
+}
+
 void QgsGrassEdit::newPoint(void) { startTool(QgsGrassEdit::NEW_POINT); }
 void QgsGrassEdit::newLine(void) { 
   std::cerr << "QgsGrassEdit::newLine" << std::endl;
diff --git a/src/plugins/grass/qgsgrassedit.h b/src/plugins/grass/qgsgrassedit.h
@@ -395,6 +395,8 @@ public slots:
     /** Snap to nearest node in current threshold */
     void snap ( QgsPoint & point );
     void snap ( double *x, double *y);
+    /** Snap point line  considering line starting point */
+    void snap ( QgsPoint & point, double startX, double startY);
 
     /** Attributes */
     QgsGrassAttributes *mAttributes;
diff --git a/src/plugins/grass/qgsgrassedittools.cpp b/src/plugins/grass/qgsgrassedittools.cpp
@@ -151,8 +151,20 @@ void QgsGrassEditNewLine::mouseClick(QgsPoint & point, Qt::ButtonState button)
 {
   switch ( button ) {
     case Qt::LeftButton:
-      e->snap ( point ); 
+      if ( e->mEditPoints->n_points > 2 )
+      {
+          e->snap ( point, e->mEditPoints->x[0], e->mEditPoints->y[0] ); 
+      }
+      else
+      {
+          e->snap ( point ); 
+      }
       Vect_append_point ( e->mEditPoints, point.x(), point.y(), 0.0 );
+
+      // Draw
+      Vect_reset_line ( e->mPoints );
+      Vect_append_points ( e->mPoints, e->mEditPoints, GV_FORWARD );
+      e->displayDynamic ( e->mPoints );
       break;
     case Qt::MidButton:
       if ( e->mEditPoints->n_points > 0 ) {
