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/***************************************************************************
qgssnapper.cpp
--------------
begin : June 7, 2007
copyright : (C) 2007 by Marco Hugentobler
email : marco dot hugentobler at karto dot baug dot ethz dot ch
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include "qgssnapper.h"
#include "qgsmaprenderer.h"
#include "qgsmaptopixel.h"
#include "qgsvectorlayer.h"
#include <QMultiMap>
#include <QPoint>
#include <cmath>
QgsSnapper::QgsSnapper( QgsMapRenderer* mapRenderer ): mMapRenderer( mapRenderer )
{
}
QgsSnapper::QgsSnapper()
{
}
QgsSnapper::~QgsSnapper()
{
}
int QgsSnapper::snapPoint( const QPoint& startPoint, QList<QgsSnappingResult>& snappingResult, const QList<QgsPoint>& excludePoints )
{
snappingResult.clear();
QMultiMap<double, QgsSnappingResult> snappingResultList;//all snapping results
QMultiMap<double, QgsSnappingResult> currentResultList; //snapping results of examined layer
//start point in (output) map coordinates
QgsPoint mapCoordPoint = mMapRenderer->coordinateTransform()->toMapCoordinates( startPoint.x(), startPoint.y() );
QgsPoint layerCoordPoint; //start point in layer coordinates
QgsSnappingResult newResult;
QList<QgsSnapper::SnapLayer>::iterator snapLayerIt;
for ( snapLayerIt = mSnapLayers.begin(); snapLayerIt != mSnapLayers.end(); ++snapLayerIt )
{
//transform point from map coordinates to layer coordinates
layerCoordPoint = mMapRenderer->mapToLayerCoordinates( snapLayerIt->mLayer, mapCoordPoint );
double tolerance = QgsTolerance::toleranceInMapUnits( snapLayerIt->mTolerance, snapLayerIt->mLayer, mMapRenderer, snapLayerIt->mUnitType );
if ( snapLayerIt->mLayer->snapWithContext( layerCoordPoint, tolerance,
currentResultList, snapLayerIt->mSnapTo ) != 0 )
{
//error
}
//transform each result from layer crs to map crs (including distance)
QMultiMap<double, QgsSnappingResult>::iterator currentResultIt;
for ( currentResultIt = currentResultList.begin(); currentResultIt != currentResultList.end(); ++currentResultIt )
{
//for each snapping result: transform start point, snap point and other points into map coordinates to find out distance
//store results in snapping result list
newResult = currentResultIt.value();
newResult.snappedVertex = mMapRenderer->layerToMapCoordinates( snapLayerIt->mLayer, currentResultIt.value().snappedVertex );
newResult.beforeVertex = mMapRenderer->layerToMapCoordinates( snapLayerIt->mLayer, currentResultIt.value().beforeVertex );
newResult.afterVertex = mMapRenderer->layerToMapCoordinates( snapLayerIt->mLayer, currentResultIt.value().afterVertex );
snappingResultList.insert( sqrt( newResult.snappedVertex.sqrDist( mapCoordPoint ) ), newResult );
}
}
//excluded specific points from result
cleanResultList( snappingResultList, excludePoints );
//evaluate results according to snap mode
QMultiMap<double, QgsSnappingResult>::iterator evalIt = snappingResultList.begin();
if ( evalIt == snappingResultList.end() )
{
return 0;
}
if ( mSnapMode == QgsSnapper::SnapWithOneResult )
{
//return only closest result
snappingResult.push_back( evalIt.value() );
}
else if ( mSnapMode == QgsSnapper::SnapWithResultsForSamePosition )
{
//take all snapping Results within a certain tolerance because rounding differences may occur
double tolerance = 0.000001;
double minDistance = evalIt.key();
for ( evalIt = snappingResultList.begin(); evalIt != snappingResultList.end(); ++evalIt )
{
if ( evalIt.key() > ( minDistance + tolerance ) )
{
break;
}
snappingResult.push_back( evalIt.value() );
}
}
else //take all results
{
for ( ; evalIt != snappingResultList.end(); ++evalIt )
{
snappingResult.push_back( evalIt.value() );
}
}
return 0;
}
void QgsSnapper::setSnapLayers( const QList<QgsSnapper::SnapLayer>& snapLayers )
{
mSnapLayers = snapLayers;
}
void QgsSnapper::setSnapMode( QgsSnapper::SnappingMode snapMode )
{
mSnapMode = snapMode;
}
void QgsSnapper::cleanResultList( QMultiMap<double, QgsSnappingResult>& list, const QList<QgsPoint>& excludeList ) const
{
QgsPoint currentResultPoint;
QgsSnappingResult currentSnappingResult;
QList<double> keysToRemove;
QMultiMap<double, QgsSnappingResult>::iterator result_it = list.begin();
for ( ; result_it != list.end(); ++result_it )
{
currentSnappingResult = result_it.value();
if ( currentSnappingResult.snappedVertexNr != -1 )
{
currentResultPoint = currentSnappingResult.snappedVertex;
if ( excludeList.contains( currentResultPoint ) )
{
keysToRemove.push_back( result_it.key() );
}
}
}
QList<double>::const_iterator remove_it = keysToRemove.constBegin();
for ( ; remove_it != keysToRemove.constEnd(); ++remove_it )
{
list.remove( *remove_it );
}
}
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