qgspainteffect.cpp

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/***************************************************************************
                              qgspainteffect.cpp
                             -------------------
    begin                : December 2014
    copyright            : (C) 2014 Nyall Dawson
    email                : nyall dot dawson at gmail dot com
 ***************************************************************************/
 
/***************************************************************************
 *                                                                         *
 *   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 "qgspainteffect.h"
 
#include "qgsimageoperation.h"
#include "qgspainting.h"
#include "qgsrendercontext.h"
#include "qgssymbollayerutils.h"
 
#include <QPicture>
#include <QString>
 
using namespace Qt::StringLiterals;
 
QgsPaintEffect::QgsPaintEffect( const QgsPaintEffect &other )
  : mEnabled( other.enabled() )
  , mDrawMode( other.drawMode() )
{}
 
QgsPaintEffect::~QgsPaintEffect()
{
  // ensure painter is destroyed before picture it may be drawing on, just in case
  mEffectPainter.reset();
}
 
Qgis::PaintEffectFlags QgsPaintEffect::flags() const
{
  return Qgis::PaintEffectFlags();
}
 
void QgsPaintEffect::setEnabled( const bool enabled )
{
  mEnabled = enabled;
}
 
void QgsPaintEffect::setDrawMode( const QgsPaintEffect::DrawMode drawMode )
{
  mDrawMode = drawMode;
}
 
bool QgsPaintEffect::saveProperties( QDomDocument &doc, QDomElement &element ) const
{
  if ( element.isNull() )
  {
    return false;
  }
  QDomElement effectElement = doc.createElement( u"effect"_s );
  effectElement.setAttribute( u"type"_s, type() );
  QgsSymbolLayerUtils::saveProperties( properties(), doc, effectElement );
  element.appendChild( effectElement );
  return true;
}
 
bool QgsPaintEffect::readProperties( const QDomElement &element )
{
  if ( element.isNull() )
  {
    return false;
  }
 
  const QVariantMap props = QgsSymbolLayerUtils::parseProperties( element );
  readProperties( props );
  return true;
}
 
void QgsPaintEffect::render( const QPicture &picture, QgsRenderContext &context )
{
  //set source picture
  mPicture = picture;
  mSourceImage = QImage();
 
  draw( context );
}
 
void QgsPaintEffect::begin( QgsRenderContext &context )
{
  //temporarily replace painter and direct paint operations for context to a QPicture
  mPrevPainter = context.painter();
 
  mTempPicture = std::make_unique< QPicture >();
 
  mEffectPainter = std::make_unique< QPainter >();
  mEffectPainter->begin( mTempPicture.get() );
 
  context.setPainterFlagsUsingContext( mEffectPainter.get() );
  context.setPainter( mEffectPainter.get() );
}
 
void QgsPaintEffect::end( QgsRenderContext &context )
{
  if ( !mEffectPainter )
    return;
 
  mEffectPainter->end();
  mEffectPainter.reset();
 
  //restore previous painter for context
  context.setPainter( mPrevPainter );
  mPrevPainter = nullptr;
 
  // clear any existing pen/brush - sometimes these are not correctly restored when restoring a painter
  // with a QPicture destination - see #15696
  context.painter()->setPen( Qt::NoPen );
  context.painter()->setBrush( Qt::NoBrush );
 
  //draw using effect
  render( *mTempPicture, context );
 
  //clean up
  mTempPicture.reset();
}
 
void QgsPaintEffect::drawSource( QPainter &painter )
{
  if ( requiresQPainterDpiFix )
  {
    QgsPainting::drawPicture( &painter, QPointF( 0, 0 ), mPicture );
  }
  else
  {
    painter.drawPicture( 0, 0, mPicture );
  }
}
 
QImage QgsPaintEffect::sourceAsImage( QgsRenderContext &context )
{
  //have we already created a source image? if so, return it
  if ( !mSourceImage.isNull() )
  {
    return mSourceImage;
  }
 
  if ( mPicture.isNull() )
    return QImage();
 
  //else create it
  //TODO - test with premultiplied image for speed
  const QRectF bounds = imageBoundingRect( context );
  mSourceImage = QImage( static_cast< int >( std::ceil( bounds.width() ) ), static_cast< int >( std::ceil( bounds.height() ) ), QImage::Format_ARGB32 );
  mSourceImage.fill( Qt::transparent );
  QPainter imagePainter( &mSourceImage );
  imagePainter.setRenderHint( QPainter::Antialiasing );
  imagePainter.translate( -bounds.left(), -bounds.top() );
  imagePainter.drawPicture( 0, 0, mPicture );
  imagePainter.end();
  return mSourceImage;
}
 
QPointF QgsPaintEffect::imageOffset( const QgsRenderContext &context ) const
{
  return imageBoundingRect( context ).topLeft();
}
 
QRectF QgsPaintEffect::boundingRect( const QRectF &rect, const QgsRenderContext &context ) const
{
  Q_UNUSED( context )
  return rect;
}
 
void QgsPaintEffect::fixQPictureDpi( QPainter *painter ) const
{
  QgsPainting::applyScaleFixForQPictureDpi( painter );
}
 
QRectF QgsPaintEffect::imageBoundingRect( const QgsRenderContext &context ) const
{
  return boundingRect( mPicture.boundingRect(), context );
}
 
 
//
// QgsDrawSourceEffect
//
 
QgsPaintEffect *QgsDrawSourceEffect::create( const QVariantMap &map )
{
  QgsDrawSourceEffect *effect = new QgsDrawSourceEffect();
  effect->readProperties( map );
  return effect;
}
 
Qgis::PaintEffectFlags QgsDrawSourceEffect::flags() const
{
  Qgis::PaintEffectFlags res;
  if ( mBlendMode != QPainter::CompositionMode_SourceOver || !qgsDoubleNear( mOpacity, 1.0 ) )
  {
    res.setFlag( Qgis::PaintEffectFlag::RequiresRasterization );
  }
  return res;
}
 
void QgsDrawSourceEffect::draw( QgsRenderContext &context )
{
  if ( !enabled() || !context.painter() )
    return;
 
  QPainter *painter = context.painter();
 
  if ( mBlendMode == QPainter::CompositionMode_SourceOver && qgsDoubleNear( mOpacity, 1.0 ) )
  {
    //just draw unmodified source
    drawSource( *painter );
  }
  else
  {
    //rasterize source and apply modifications
    QImage image = sourceAsImage( context ).copy();
    QgsImageOperation::multiplyOpacity( image, mOpacity, context.feedback() );
    const QgsScopedQPainterState painterState( painter );
    painter->setCompositionMode( mBlendMode );
    painter->drawImage( imageOffset( context ), image );
  }
}
 
QgsDrawSourceEffect *QgsDrawSourceEffect::clone() const
{
  return new QgsDrawSourceEffect( *this );
}
 
QVariantMap QgsDrawSourceEffect::properties() const
{
  QVariantMap props;
  props.insert( u"enabled"_s, mEnabled ? "1" : "0" );
  props.insert( u"draw_mode"_s, QString::number( int( mDrawMode ) ) );
  props.insert( u"blend_mode"_s, QString::number( int( mBlendMode ) ) );
  props.insert( u"opacity"_s, QString::number( mOpacity ) );
  return props;
}
 
void QgsDrawSourceEffect::readProperties( const QVariantMap &props )
{
  bool ok;
  const QPainter::CompositionMode mode = static_cast< QPainter::CompositionMode >( props.value( u"blend_mode"_s ).toInt( &ok ) );
  if ( ok )
  {
    mBlendMode = mode;
  }
  if ( props.contains( u"transparency"_s ) )
  {
    const double transparency = props.value( u"transparency"_s ).toDouble( &ok );
    if ( ok )
    {
      mOpacity = 1.0 - transparency;
    }
  }
  else
  {
    const double opacity = props.value( u"opacity"_s ).toDouble( &ok );
    if ( ok )
    {
      mOpacity = opacity;
    }
  }
  mEnabled = props.value( u"enabled"_s, u"1"_s ).toInt();
  mDrawMode = static_cast< QgsPaintEffect::DrawMode >( props.value( u"draw_mode"_s, u"2"_s ).toInt() );
}
 
 
//
// QgsEffectPainter
//
 
QgsEffectPainter::QgsEffectPainter( QgsRenderContext &renderContext )
  : mRenderContext( renderContext )
 
{
  mPainter = renderContext.painter();
  mPainter->save();
}
 
QgsEffectPainter::QgsEffectPainter( QgsRenderContext &renderContext, QgsPaintEffect *effect )
  : mRenderContext( renderContext )
  , mEffect( effect )
{
  mPainter = mRenderContext.painter();
  mPainter->save();
  mEffect->begin( mRenderContext );
}
 
void QgsEffectPainter::setEffect( QgsPaintEffect *effect )
{
  Q_ASSERT( !mEffect );
 
  mEffect = effect;
  mEffect->begin( mRenderContext );
}
 
QgsEffectPainter::~QgsEffectPainter()
{
  Q_ASSERT( mEffect );
 
  mEffect->end( mRenderContext );
  mPainter->restore();
}