qgsrasterdrawer.cpp

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/***************************************************************************
                         qgsrasterdrawer.cpp
                         ---------------------
    begin                : June 2012
    copyright            : (C) 2012 by Radim Blazek
    email                : radim dot blazek at gmail.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 "qgsrasterdrawer.h"
 
#include "qgslogger.h"
#include "qgsmaptopixel.h"
#include "qgsrasterblock.h"
#include "qgsrasterinterface.h"
#include "qgsrasteriterator.h"
#include "qgsrasterviewport.h"
#include "qgsrendercontext.h"
 
#include <QImage>
#include <QPainter>
#include <QPdfWriter>
#include <QString>
 
using namespace Qt::StringLiterals;
 
QgsRasterDrawer::QgsRasterDrawer( QgsRasterIterator *iterator, double dpiTarget )
  : mIterator( iterator )
  , mDpiTarget( dpiTarget )
{}
 
QgsRasterDrawer::QgsRasterDrawer( QgsRasterIterator *iterator )
  : mIterator( iterator )
{}
 
void QgsRasterDrawer::draw( QgsRenderContext &context, QgsRasterViewPort *viewPort, QgsRasterBlockFeedback *feedback )
{
  mDpiScaleFactor = context.dpiTarget() >= 0.0 ? context.dpiTarget() / ( context.scaleFactor() * 25.4 ) : 1.0;
  mDevicePixelRatio = context.devicePixelRatio();
 
  draw( context.painter(), viewPort, &context.mapToPixel(), feedback );
}
 
void QgsRasterDrawer::draw( QPainter *p, QgsRasterViewPort *viewPort, const QgsMapToPixel *qgsMapToPixel, QgsRasterBlockFeedback *feedback )
{
  QgsDebugMsgLevel( u"Entered"_s, 4 );
  if ( !p || !mIterator || !viewPort || !qgsMapToPixel )
  {
    return;
  }
 
  if ( mDpiTarget >= 0 )
  {
    mDpiScaleFactor = mDpiTarget / p->device()->logicalDpiX();
  }
 
  // last pipe filter has only 1 band
  const int bandNumber = 1;
  mIterator
    ->startRasterRead( bandNumber, std::floor( static_cast<double>( viewPort->mWidth ) * mDevicePixelRatio ), std::floor( static_cast<double>( viewPort->mHeight ) * mDevicePixelRatio ), viewPort->mDrawnExtent, feedback );
 
  //number of cols/rows in output pixels
  int nCols = 0;
  int nRows = 0;
  //shift to top left point for the raster part
  int topLeftCol = 0;
  int topLeftRow = 0;
 
  // We know that the output data type of last pipe filter is QImage data
 
  std::unique_ptr< QgsRasterBlock > block;
 
  // readNextRasterPart calcs and resets  nCols, nRows, topLeftCol, topLeftRow
  while ( mIterator->readNextRasterPart( bandNumber, nCols, nRows, block, topLeftCol, topLeftRow ) )
  {
    if ( !block )
    {
      QgsDebugError( u"Cannot get block"_s );
      continue;
    }
 
    QImage img = block->image();
 
    // Because of bug in Acrobat Reader we must use "white" transparent color instead
    // of "black" for PDF. See #9101.
    QPdfWriter *pdfWriter = dynamic_cast<QPdfWriter *>( p->device() );
    if ( pdfWriter )
    {
      QgsDebugMsgLevel( u"PdfFormat"_s, 4 );
 
      img = img.convertToFormat( QImage::Format_ARGB32 );
      const QRgb transparentBlack = qRgba( 0, 0, 0, 0 );
      const QRgb transparentWhite = qRgba( 255, 255, 255, 0 );
      for ( int x = 0; x < img.width(); x++ )
      {
        for ( int y = 0; y < img.height(); y++ )
        {
          if ( img.pixel( x, y ) == transparentBlack )
          {
            img.setPixel( x, y, transparentWhite );
          }
        }
      }
    }
 
    if ( feedback && feedback->renderPartialOutput() )
    {
      // there could have been partial preview written before
      // so overwrite anything with the resulting image.
      // (we are guaranteed to have a temporary image for this layer, see QgsMapRendererJob::needTemporaryImage)
      p->setCompositionMode( QPainter::CompositionMode_Source );
    }
 
    drawImage( p, viewPort, img, topLeftCol, topLeftRow, qgsMapToPixel );
 
    if ( feedback && feedback->renderPartialOutput() )
    {
      // go back to the default composition mode
      p->setCompositionMode( QPainter::CompositionMode_SourceOver );
    }
 
    // OK this does not matter much anyway as the tile size quite big so most of the time
    // there would be just one tile for the whole display area, but it won't hurt...
    if ( feedback && feedback->isCanceled() )
      break;
  }
}
 
void QgsRasterDrawer::drawImage( QPainter *p, QgsRasterViewPort *viewPort, const QImage &img, int topLeftCol, int topLeftRow, const QgsMapToPixel *qgsMapToPixel ) const
{
  if ( !p || !viewPort )
  {
    return;
  }
 
  // top left position in device coords
  const QPoint tlPoint
    = QPoint( std::floor( viewPort->mTopLeftPoint.x() + topLeftCol / mDpiScaleFactor / mDevicePixelRatio ), std::floor( viewPort->mTopLeftPoint.y() + topLeftRow / mDpiScaleFactor / mDevicePixelRatio ) );
  const QgsScopedQPainterState painterState( p );
 
  // Improve rendering of rasters on high DPI screens with Qt's auto scaling enabled
  if ( !qgsDoubleNear( mDevicePixelRatio, 1.0 ) || !qgsDoubleNear( mDpiScaleFactor, 1.0 ) )
  {
    p->setRenderHint( QPainter::SmoothPixmapTransform, true );
  }
 
  // Blending problem was reported with PDF output if background color has alpha < 255
  // in #7766, it seems to be a bug in Qt, setting a brush with alpha 255 is a workaround
  // which should not harm anything
  p->setBrush( QBrush( QColor( Qt::white ), Qt::NoBrush ) );
  if ( qgsMapToPixel )
  {
    const int w = qgsMapToPixel->mapWidth();
    const int h = qgsMapToPixel->mapHeight();
    const double rotation = qgsMapToPixel->mapRotation();
    if ( rotation )
    {
      // both viewPort and image sizes are dependent on scale
      const double cx = w / 2.0;
      const double cy = h / 2.0;
      p->translate( cx, cy );
      p->rotate( rotation );
      p->translate( -cx, -cy );
    }
  }
 
  p->drawImage( QRect( tlPoint.x(), tlPoint.y(), std::ceil( img.width() / mDpiScaleFactor / mDevicePixelRatio ), std::ceil( img.height() / mDpiScaleFactor / mDevicePixelRatio ) ), img );
 
#if 0
  // For debugging:
  QRectF br = QRectF( tlPoint, img.size() / mDpiScaleFactor / devicePixelRatio );
  QPointF c = br.center();
  double rad = std::max( br.width(), br.height() ) / 10;
  p->drawRoundedRect( br, rad, rad );
  p->drawLine( QLineF( br.x(), br.y(), br.x() + br.width(), br.y() + br.height() ) );
  p->drawLine( QLineF( br.x() + br.width(), br.y(), br.x(), br.y() + br.height() ) );
 
  double nw = br.width() * 0.5;
  double nh = br.height() * 0.5;
  br = QRectF( c - QPointF( nw / 2, nh / 2 ), QSize( nw, nh ) );
  p->drawRoundedRect( br, rad, rad );
 
  nw = br.width() * 0.5;
  nh = br.height() * 0.5;
  br = QRectF( c - QPointF( nw / 2, nh / 2 ), QSize( nw, nh ) );
  p->drawRoundedRect( br, rad, rad );
#endif
}