qgshighlight.cpp

Go to the documentation of this file.

/***************************************************************************
    qgshighlight.cpp - widget to highlight features on the map
     --------------------------------------
    Date                 : 02-03-2011
    Copyright            : (C) 2011 by Juergen E. Fischer, norBIT GmbH
    Email                : jef at norbit dot de
 ***************************************************************************
 *                                                                         *
 *   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 <QImage>
 
#include "qgsmarkersymbollayer.h"
#include "qgslinesymbollayer.h"
 
#include "qgscoordinatetransform.h"
#include "qgsfillsymbollayer.h"
#include "qgsgeometry.h"
#include "qgshighlight.h"
#include "qgsmapcanvas.h"
#include "qgsmaplayer.h"
#include "qgsrendercontext.h"
#include "qgssymbollayer.h"
#include "qgssymbol.h"
#include "qgsvectorlayer.h"
#include "qgsrenderer.h"
#include "qgsexpressioncontextutils.h"
#include "qgspointcloudlayer.h"
#include "qgssinglesymbolrenderer.h"
#include "qgspointcloudlayerrenderer.h"
 
/* Few notes about highlighting (RB):
 - The highlight fill must always be partially transparent because above highlighted layer
   may be another layer which must remain partially visible.
 - Because single highlight color does not work well with layers using similar layer color
   there were considered various possibilities but no optimal solution was found.
   What does not work:
   - lighter/darker color: it would work more or less for fully opaque highlight, but
     overlaying transparent lighter color over original has small visual effect.
   - complemetary color: mixing transparent (128) complement color with original color
     results in grey for all colors
   - contrast line style/ fill pattern: impression is not highligh but just different style
   - line buffer with contrast (or 2 contrast) color: the same as with patterns, no highlight impression
   - fill with highlight or contrast color but opaque and using pattern
     (e.g. Qt::Dense7Pattern): again no highlight impression
*/
 
QgsHighlight::QgsHighlight( QgsMapCanvas *mapCanvas, const QgsGeometry &geom, QgsMapLayer *layer )
  : QgsMapCanvasItem( mapCanvas )
  , mGeometry( geom )
  , mLayer( layer )
 
{
  init();
}
 
QgsHighlight::QgsHighlight( QgsMapCanvas *mapCanvas, const QgsFeature &feature, QgsVectorLayer *layer )
  : QgsMapCanvasItem( mapCanvas )
  , mLayer( layer )
  , mFeature( feature )
{
  init();
}
 
void QgsHighlight::init()
{
  mOriginalGeometry = mGeometry.isNull() ? mFeature.geometry() : mGeometry;
  setColor( QColor( Qt::lightGray ) );
 
  connect( mMapCanvas, &QgsMapCanvas::destinationCrsChanged, this, &QgsHighlight::updateTransformedGeometry );
  updateTransformedGeometry();
 
  if ( mGeometry.type() == QgsWkbTypes::PointGeometry )
  {
    mRenderContext = createRenderContext();
  }
}
 
void QgsHighlight::updateTransformedGeometry()
{
  const QgsCoordinateTransform ct = mMapCanvas->mapSettings().layerTransform( mLayer );
 
  // we don't auto-transform if we are highlighting a feature -- the renderer will take care
  // of that for us
  if ( ct.isValid() && !mGeometry.isNull() )
  {
    // reset to original geometry and transform
    mGeometry = mOriginalGeometry;
    try
    {
      mGeometry.transform( ct );
    }
    catch ( QgsCsException & )
    {
      QgsDebugMsg( QStringLiteral( "Could not transform highlight geometry to canvas CRS" ) );
    }
  }
  updateRect();
  update();
}
 
QgsHighlight::~QgsHighlight() = default;
 
void QgsHighlight::setColor( const QColor &color )
{
  mColor = color;
  mPen.setColor( color );
  QColor fillColor( color.red(), color.green(), color.blue(), 63 );
  mBrush.setColor( fillColor );
  mBrush.setStyle( Qt::SolidPattern );
}
 
void QgsHighlight::setFillColor( const QColor &fillColor )
{
  mFillColor = fillColor;
  mBrush.setColor( fillColor );
  mBrush.setStyle( Qt::SolidPattern );
}
 
std::unique_ptr<QgsFeatureRenderer> QgsHighlight::createRenderer( QgsRenderContext &context, const QColor &color, const QColor &fillColor )
{
  std::unique_ptr<QgsFeatureRenderer> renderer;
  QgsVectorLayer *layer = qobject_cast<QgsVectorLayer *>( mLayer );
  if ( layer && layer->renderer() )
  {
    renderer.reset( layer->renderer()->clone() );
  }
  if ( renderer )
  {
    const QgsSymbolList symbols = renderer->symbols( context );
    for ( QgsSymbol *symbol : symbols )
    {
      if ( !symbol )
        continue;
      setSymbol( symbol, context, color, fillColor );
    }
  }
  return renderer;
}
 
void QgsHighlight::setSymbol( QgsSymbol *symbol, const QgsRenderContext &context,   const QColor &color, const QColor &fillColor )
{
  if ( !symbol )
    return;
 
  for ( int i = symbol->symbolLayerCount() - 1; i >= 0;  i-- )
  {
    QgsSymbolLayer *symbolLayer = symbol->symbolLayer( i );
    if ( !symbolLayer )
      continue;
 
    if ( symbolLayer->subSymbol() )
    {
      setSymbol( symbolLayer->subSymbol(), context, color, fillColor );
    }
    else
    {
      symbolLayer->setColor( color ); // line symbology layers
      symbolLayer->setStrokeColor( color ); // marker and fill symbology layers
      symbolLayer->setFillColor( fillColor ); // marker and fill symbology layers
 
      // Data defined widths overwrite what we set here (widths do not work with data defined)
      QgsSimpleMarkerSymbolLayer *simpleMarker = dynamic_cast<QgsSimpleMarkerSymbolLayer *>( symbolLayer );
      if ( simpleMarker )
      {
        simpleMarker->setStrokeWidth( getSymbolWidth( context, simpleMarker->strokeWidth(), simpleMarker->strokeWidthUnit() ) );
      }
      QgsSimpleLineSymbolLayer *simpleLine = dynamic_cast<QgsSimpleLineSymbolLayer *>( symbolLayer );
      if ( simpleLine )
      {
        simpleLine->setWidth( getSymbolWidth( context, simpleLine->width(), simpleLine->widthUnit() ) );
      }
      QgsSimpleFillSymbolLayer *simpleFill = dynamic_cast<QgsSimpleFillSymbolLayer *>( symbolLayer );
      if ( simpleFill )
      {
        simpleFill->setStrokeWidth( getSymbolWidth( context, simpleFill->strokeWidth(), simpleFill->outputUnit() ) );
      }
      symbolLayer->setDataDefinedProperty( QgsSymbolLayer::PropertyFillColor, QgsProperty() );
      symbolLayer->setDataDefinedProperty( QgsSymbolLayer::PropertyStrokeColor, QgsProperty() );
    }
  }
}
 
double QgsHighlight::getSymbolWidth( const QgsRenderContext &context, double width, QgsUnitTypes::RenderUnit unit )
{
  // if necessary scale mm to map units
  double scale = 1.;
  if ( unit == QgsUnitTypes::RenderMapUnits )
  {
    scale = context.convertToPainterUnits( 1, QgsUnitTypes::RenderMillimeters ) / context.convertToPainterUnits( 1, QgsUnitTypes::RenderMapUnits );
  }
  width = std::max( width + 2 * mBuffer * scale, mMinWidth * scale );
  return width;
}
 
void QgsHighlight::setWidth( int width )
{
  mWidth = width;
  mPen.setWidth( width );
}
 
void QgsHighlight::paintPoint( QgsRenderContext &context, const QgsPoint *point, double size, QgsUnitTypes::RenderUnit sizeUnit, PointSymbol symbol )
{
  if ( !point )
    return;
 
  const double radius = context.convertToPainterUnits( size, sizeUnit );
  const double xMin = toCanvasCoordinates( *point ).x() - radius - pos().x();
  const double yMin = toCanvasCoordinates( *point ).y() - radius - pos().y();
 
  switch ( symbol )
  {
    case QgsHighlight::Square:
    {
      const double xMax = xMin + 2 * radius;
      const double yMax = yMin + 2 * radius;
      QPolygonF r( QVector<QPointF> { QPointF( xMin, yMin ),
                                      QPointF( xMax, yMin ),
                                      QPointF( xMax, yMax ),
                                      QPointF( xMin, yMax ),
                                      QPointF( xMin, yMin )
                                    } );
      context.painter()->drawPolygon( r );
      break;
    }
 
    case QgsHighlight::Circle:
    {
      context.painter()->drawEllipse( QRectF( xMin, yMin, radius * 2, radius * 2 ) );
      break;
    }
  }
}
 
void QgsHighlight::paintLine( QPainter *p, QgsPolylineXY line )
{
  QPolygonF polygon( line.size() );
 
  for ( int i = 0; i < line.size(); i++ )
  {
    polygon[i] = toCanvasCoordinates( line[i] ) - pos();
  }
 
  p->drawPolyline( polygon );
}
 
void QgsHighlight::paintPolygon( QPainter *p, const QgsPolygonXY &polygon )
{
  // OddEven fill rule by default
  QPainterPath path;
 
  p->setPen( mPen );
  p->setBrush( mBrush );
 
  for ( const auto &sourceRing : polygon )
  {
    if ( sourceRing.empty() )
      continue;
 
    QPolygonF ring;
    ring.reserve( sourceRing.size() + 1 );
 
    QPointF lastVertex;
    for ( const auto &sourceVertex : sourceRing )
    {
      //adding point only if it is more than a pixel apart from the previous one
      const QPointF curVertex = toCanvasCoordinates( sourceVertex ) - pos();
      if ( ring.isEmpty() || std::abs( ring.back().x() - curVertex.x() ) > 1 || std::abs( ring.back().y() - curVertex.y() ) > 1 )
      {
        ring.push_back( curVertex );
      }
      lastVertex = curVertex;
    }
 
    ring.push_back( ring.at( 0 ) );
 
    path.addPolygon( ring );
  }
 
  p->drawPath( path );
}
 
QgsRenderContext QgsHighlight::createRenderContext()
{
  QgsMapSettings mapSettings = mMapCanvas->mapSettings();
  QgsRenderContext context = QgsRenderContext::fromMapSettings( mapSettings );
  context.expressionContext() << QgsExpressionContextUtils::layerScope( mLayer );
  return context;
}
 
void QgsHighlight::updatePosition()
{
  if ( !isVisible() )
    return;
 
  if ( mGeometry.type() == QgsWkbTypes::PointGeometry )
  {
    mRenderContext = createRenderContext();
  }
 
  updateRect();
}
 
void QgsHighlight::paint( QPainter *p )
{
  if ( mFeature.hasGeometry() )
  {
    QgsVectorLayer *vlayer = qobject_cast<QgsVectorLayer *>( mLayer );
    if ( !vlayer )
      return;
 
    QgsRenderContext context = createRenderContext();
    const QgsCoordinateTransform layerToCanvasTransform = mMapCanvas->mapSettings().layerTransform( mLayer );
    context.setCoordinateTransform( layerToCanvasTransform );
    QgsRectangle mapExtentInLayerCrs = mMapCanvas->mapSettings().visibleExtent();
    if ( layerToCanvasTransform.isValid() )
    {
      QgsCoordinateTransform approxTransform = layerToCanvasTransform;
      approxTransform.setBallparkTransformsAreAppropriate( true );
      try
      {
        mapExtentInLayerCrs = approxTransform.transformBoundingBox( mapExtentInLayerCrs, Qgis::TransformDirection::Reverse );
      }
      catch ( QgsCsException & )
      {
        QgsDebugMsg( QStringLiteral( "Error transforming canvas extent to layer CRS" ) );
      }
    }
    if ( !mapExtentInLayerCrs.isFinite() )
    {
      return;
    }
    context.setExtent( mapExtentInLayerCrs );
 
    // Because lower level outlines must be covered by upper level fill color
    // we render first with temporary opaque color, which is then replaced
    // by final transparent fill color.
    QColor tmpColor( 255, 0, 0, 255 );
    QColor tmpFillColor( 0, 255, 0, 255 );
 
    std::unique_ptr< QgsFeatureRenderer > renderer = createRenderer( context, tmpColor, tmpFillColor );
    if ( renderer )
    {
 
      QSize imageSize( mMapCanvas->mapSettings().outputSize() );
      QImage image = QImage( imageSize.width(), imageSize.height(), QImage::Format_ARGB32 );
      image.fill( 0 );
      QPainter imagePainter( &image );
      imagePainter.setRenderHint( QPainter::Antialiasing, true );
 
      context.setPainter( &imagePainter );
      renderer->startRender( context, mFeature.fields() );
      context.expressionContext().setFeature( mFeature );
      renderer->renderFeature( mFeature, context );
      renderer->stopRender( context );
 
      imagePainter.end();
 
      // true output color
      int penRed = mPen.color().red();
      int penGreen = mPen.color().green();
      int penBlue = mPen.color().blue();
      // coefficient to subtract alpha using green (temporary fill)
      double k = ( 255. - mBrush.color().alpha() ) / 255.;
      QRgb *line = nullptr;
      const int height = image.height();
      const int width = image.width();
      for ( int r = 0; r < height; r++ )
      {
        line = reinterpret_cast<QRgb *>( image.scanLine( r ) );
        for ( int c = 0; c < width; c++ )
        {
          int alpha = qAlpha( line[c] );
          if ( alpha > 0 )
          {
            int green = qGreen( line[c] );
            line[c] = qRgba( penRed, penGreen, penBlue, std::clamp( static_cast< int >( alpha - ( green * k ) ), 0, 255 ) );
          }
        }
      }
 
      p->drawImage( 0, 0, image );
    }
  }
  else if ( !mGeometry.isNull() )
  {
    p->setPen( mPen );
    p->setBrush( mBrush );
 
    switch ( mGeometry.type() )
    {
      case QgsWkbTypes::PointGeometry:
      {
        setRenderContextVariables( p, mRenderContext );
 
        // default to 1.5 mm radius square points
        double pointSizeRadius = 1.5;
        QgsUnitTypes::RenderUnit sizeUnit = QgsUnitTypes::RenderMillimeters;
        PointSymbol symbol = Square;
 
        // but for point clouds, use actual sizes (+a little margin!)
        if ( QgsPointCloudLayer *pcLayer = qobject_cast<QgsPointCloudLayer *>( mLayer ) )
        {
          if ( QgsPointCloudRenderer *pcRenderer = pcLayer->renderer() )
          {
            pointSizeRadius = 1.2 * 0.5 * mRenderContext.convertToPainterUnits( pcRenderer->pointSize(), pcRenderer->pointSizeUnit(), pcRenderer->pointSizeMapUnitScale() );
            sizeUnit = QgsUnitTypes::RenderPixels;
            switch ( pcRenderer->pointSymbol() )
            {
              case Qgis::PointCloudSymbol::Circle:
                symbol = Circle;
                break;
              case Qgis::PointCloudSymbol::Square:
                symbol = Square;
                break;
            }
          }
        }
 
        for ( auto it = mGeometry.const_parts_begin(); it != mGeometry.const_parts_end(); ++it )
        {
          paintPoint( mRenderContext, qgsgeometry_cast< const QgsPoint *>( *it ), pointSizeRadius, sizeUnit, symbol );
        }
      }
      break;
 
      case QgsWkbTypes::LineGeometry:
      {
        if ( !mGeometry.isMultipart() )
        {
          paintLine( p, mGeometry.asPolyline() );
        }
        else
        {
          QgsMultiPolylineXY m = mGeometry.asMultiPolyline();
 
          for ( int i = 0; i < m.size(); i++ )
          {
            paintLine( p, m[i] );
          }
        }
        break;
      }
 
      case QgsWkbTypes::PolygonGeometry:
      {
        if ( !mGeometry.isMultipart() )
        {
          paintPolygon( p, mGeometry.asPolygon() );
        }
        else
        {
          QgsMultiPolygonXY m = mGeometry.asMultiPolygon();
          for ( int i = 0; i < m.size(); i++ )
          {
            paintPolygon( p, m[i] );
          }
        }
        break;
      }
 
      case QgsWkbTypes::UnknownGeometry:
      case QgsWkbTypes::NullGeometry:
        return;
    }
  }
}
 
void QgsHighlight::updateRect()
{
  if ( qobject_cast<QgsPointCloudLayer *>( mLayer ) || mFeature.hasGeometry() )
  {
    // We are currently using full map canvas extent for two reasons:
    // 1) currently there is no method in QgsFeatureRenderer to get rendered feature
    //    bounding box
    // 2) using different extent would result in shifted fill patterns
 
    // This is an hack to pass QgsMapCanvasItem::setRect what it
    // expects (encoding of position and size of the item)
    const QgsMapToPixel &m2p = mMapCanvas->mapSettings().mapToPixel();
    QgsPointXY topLeft = m2p.toMapCoordinates( 0, 0 );
    double res = m2p.mapUnitsPerPixel();
    QSizeF imageSize = mMapCanvas->mapSettings().outputSize();
    QgsRectangle rect( topLeft.x(), topLeft.y(), topLeft.x() + imageSize.width()*res, topLeft.y() - imageSize.height()*res );
    setRect( rect );
 
    setVisible( true );
  }
  else if ( !mGeometry.isNull() )
  {
    QgsRectangle r = mGeometry.boundingBox();
 
    if ( r.isEmpty() )
    {
      double d = mMapCanvas->extent().width() * 0.005;
      r.setXMinimum( r.xMinimum() - d );
      r.setYMinimum( r.yMinimum() - d );
      r.setXMaximum( r.xMaximum() + d );
      r.setYMaximum( r.yMaximum() + d );
    }
 
    setRect( r );
    setVisible( true );
  }
  else
  {
    setRect( QgsRectangle() );
  }
}