C++ QgsSymbolRenderContext::feature方法代码示例

void QgsVectorFieldSymbolLayer::renderPoint( QPointF point, QgsSymbolRenderContext& context )
{
  if ( !mLineSymbol )
  {
    return;
  }

  const QgsRenderContext& ctx = context.renderContext();

  const QgsFeature* f = context.feature();
  if ( !f )
  {
    //preview
    QPolygonF line;
    line << QPointF( 0, 50 );
    line << QPointF( 100, 50 );
    mLineSymbol->renderPolyline( line, nullptr, context.renderContext() );
  }

  double xComponent = 0;
  double yComponent = 0;

  double xVal = 0;
  if ( f && mXIndex != -1 )
  {
    xVal = f->attribute( mXIndex ).toDouble();
  }
  double yVal = 0;
  if ( f && mYIndex != -1 )
  {
    yVal = f->attribute( mYIndex ).toDouble();
  }

  switch ( mVectorFieldType )
  {
    case Cartesian:
      xComponent = QgsSymbolLayerUtils::convertToPainterUnits( ctx, xVal, mDistanceUnit, mDistanceMapUnitScale );
      yComponent = QgsSymbolLayerUtils::convertToPainterUnits( ctx, yVal, mDistanceUnit, mDistanceMapUnitScale );
      break;
    case Polar:
      convertPolarToCartesian( xVal, yVal, xComponent, yComponent );
      xComponent = QgsSymbolLayerUtils::convertToPainterUnits( ctx, xComponent, mDistanceUnit, mDistanceMapUnitScale );
      yComponent = QgsSymbolLayerUtils::convertToPainterUnits( ctx, yComponent, mDistanceUnit, mDistanceMapUnitScale );
      break;
    case Height:
      xComponent = 0;
      yComponent = QgsSymbolLayerUtils::convertToPainterUnits( ctx, yVal, mDistanceUnit, mDistanceMapUnitScale );
      break;
    default:
      break;
  }

  xComponent *= mScale;
  yComponent *= mScale;

  QPolygonF line;
  line << point;
  line << QPointF( point.x() + xComponent, point.y() - yComponent );
  mLineSymbol->renderPolyline( line, f, context.renderContext() );
}

QVariant QgsSymbolLayer::evaluateDataDefinedProperty( const QString& property, const QgsSymbolRenderContext& context, const QVariant& defaultVal, bool* ok ) const
{
  if ( ok )
    *ok = false;

  QgsDataDefined* dd = getDataDefinedProperty( property );
  if ( !dd || !dd->isActive() )
    return defaultVal;

  if ( dd->useExpression() )
  {
    if ( dd->expression() )
    {
      QVariant result = dd->expression()->evaluate( &context.renderContext().expressionContext() );
      if ( result.isValid() )
      {
        if ( ok )
          *ok = true;
        return result;
      }
      else
        return defaultVal;
    }
    else
    {
      return defaultVal;
    }
  }
  else if ( context.feature() && !dd->field().isEmpty() && !mFields.isEmpty() )
  {
    int attributeIndex = mFields.lookupField( dd->field() );
    if ( attributeIndex >= 0 )
    {
      if ( ok )
        *ok = true;
      return context.feature()->attribute( attributeIndex );
    }
  }
  return defaultVal;
}

void QgsEllipseSymbolLayer::startRender( QgsSymbolRenderContext &context )
{
  QgsMarkerSymbolLayer::startRender( context ); // get anchor point expressions
  if ( !context.feature() || !dataDefinedProperties().hasActiveProperties() )
  {
    preparePath( mSymbolName, context );
  }
  mPen.setColor( mStrokeColor );
  mPen.setStyle( mStrokeStyle );
  mPen.setJoinStyle( mPenJoinStyle );
  mPen.setWidthF( context.renderContext().convertToPainterUnits( mStrokeWidth, mStrokeWidthUnit, mStrokeWidthMapUnitScale ) );
  mBrush.setColor( mColor );
}

void QgsEllipseSymbolLayer::calculateOffsetAndRotation( QgsSymbolRenderContext &context,
    double scaledWidth,
    double scaledHeight,
    bool &hasDataDefinedRotation,
    QPointF &offset,
    double &angle ) const
{
  double offsetX = 0;
  double offsetY = 0;
  markerOffset( context, scaledWidth, scaledHeight, mSymbolWidthUnit, mSymbolHeightUnit, offsetX, offsetY, mSymbolWidthMapUnitScale, mSymbolHeightMapUnitScale );
  offset = QPointF( offsetX, offsetY );

//priority for rotation: 1. data defined symbol level, 2. symbol layer rotation (mAngle)
  bool ok = true;
  angle = mAngle + mLineAngle;
  bool usingDataDefinedRotation = false;
  if ( mDataDefinedProperties.isActive( QgsSymbolLayer::PropertyAngle ) )
  {
    context.setOriginalValueVariable( angle );
    angle = mDataDefinedProperties.valueAsDouble( QgsSymbolLayer::PropertyAngle, context.renderContext().expressionContext(), 0 ) + mLineAngle;
    usingDataDefinedRotation = ok;
  }

  hasDataDefinedRotation = context.renderHints() & QgsSymbol::DynamicRotation || usingDataDefinedRotation;
  if ( hasDataDefinedRotation )
  {
    // For non-point markers, "dataDefinedRotation" means following the
    // shape (shape-data defined). For them, "field-data defined" does
    // not work at all. TODO: if "field-data defined" ever gets implemented
    // we'll need a way to distinguish here between the two, possibly
    // using another flag in renderHints()
    const QgsFeature *f = context.feature();
    if ( f )
    {
      const QgsGeometry g = f->geometry();
      if ( !g.isNull() && g.type() == QgsWkbTypes::PointGeometry )
      {
        const QgsMapToPixel &m2p = context.renderContext().mapToPixel();
        angle += m2p.mapRotation();
      }
    }
  }

  if ( angle )
    offset = _rotatedOffset( offset, angle );
}

void QgsEllipseSymbolLayer::renderPoint( QPointF point, QgsSymbolRenderContext &context )
{
  double scaledWidth = mSymbolWidth;
  double scaledHeight = mSymbolHeight;

  if ( mDataDefinedProperties.hasActiveProperties() )
  {
    bool ok;
    context.setOriginalValueVariable( mStrokeWidth );
    QVariant exprVal = mDataDefinedProperties.value( QgsSymbolLayer::PropertyStrokeWidth, context.renderContext().expressionContext() );
    if ( exprVal.isValid() )
    {
      double width = exprVal.toDouble( &ok );
      if ( ok )
      {
        width = context.renderContext().convertToPainterUnits( width, mStrokeWidthUnit, mStrokeWidthMapUnitScale );
        mPen.setWidthF( width );
      }
    }

    context.setOriginalValueVariable( QgsSymbolLayerUtils::encodePenStyle( mStrokeStyle ) );
    exprVal = mDataDefinedProperties.value( QgsSymbolLayer::PropertyStrokeStyle, context.renderContext().expressionContext() );
    if ( exprVal.isValid() )
    {
      mPen.setStyle( QgsSymbolLayerUtils::decodePenStyle( exprVal.toString() ) );
    }

    context.setOriginalValueVariable( QgsSymbolLayerUtils::encodePenJoinStyle( mPenJoinStyle ) );
    exprVal = mDataDefinedProperties.value( QgsSymbolLayer::PropertyJoinStyle, context.renderContext().expressionContext() );
    if ( exprVal.isValid() )
    {
      mPen.setJoinStyle( QgsSymbolLayerUtils::decodePenJoinStyle( exprVal.toString() ) );
    }

    context.setOriginalValueVariable( QgsSymbolLayerUtils::encodeColor( mColor ) );
    mBrush.setColor( mDataDefinedProperties.valueAsColor( QgsSymbolLayer::PropertyFillColor, context.renderContext().expressionContext(), mColor ) );

    context.setOriginalValueVariable( QgsSymbolLayerUtils::encodeColor( mStrokeColor ) );
    mPen.setColor( mDataDefinedProperties.valueAsColor( QgsSymbolLayer::PropertyStrokeColor, context.renderContext().expressionContext(), mStrokeColor ) );

    if ( mDataDefinedProperties.isActive( QgsSymbolLayer::PropertyWidth ) || mDataDefinedProperties.isActive( QgsSymbolLayer::PropertyHeight ) || mDataDefinedProperties.isActive( QgsSymbolLayer::PropertyName ) )
    {
      QString symbolName = mSymbolName;
      context.setOriginalValueVariable( mSymbolName );
      exprVal = mDataDefinedProperties.value( QgsSymbolLayer::PropertyName, context.renderContext().expressionContext() );
      if ( exprVal.isValid() )
      {
        symbolName = exprVal.toString();
      }
      preparePath( symbolName, context, &scaledWidth, &scaledHeight, context.feature() );
    }
  }

  //offset and rotation
  bool hasDataDefinedRotation = false;
  QPointF offset;
  double angle = 0;
  calculateOffsetAndRotation( context, scaledWidth, scaledHeight, hasDataDefinedRotation, offset, angle );

  QPainter *p = context.renderContext().painter();
  if ( !p )
  {
    return;
  }

  QMatrix transform;
  transform.translate( point.x() + offset.x(), point.y() + offset.y() );
  if ( !qgsDoubleNear( angle, 0.0 ) )
  {
    transform.rotate( angle );
  }

  p->setPen( mPen );
  p->setBrush( mBrush );
  p->drawPath( transform.map( mPainterPath ) );
}