qgsimagecache.cpp

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/***************************************************************************
                         qgsimagecache.cpp
                         -----------------
    begin                : December 2018
    copyright            : (C) 2018 by 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 "qgsimagecache.h"
 
#include "qgis.h"
#include "qgsimageoperation.h"
#include "qgslogger.h"
#include "qgsnetworkaccessmanager.h"
#include "qgsmessagelog.h"
#include "qgsnetworkcontentfetchertask.h"
#include "qgssettings.h"
 
#include <QApplication>
#include <QCoreApplication>
#include <QCursor>
#include <QDomDocument>
#include <QDomElement>
#include <QFile>
#include <QImage>
#include <QPainter>
#include <QPicture>
#include <QFileInfo>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QBuffer>
#include <QImageReader>
#include <QSvgRenderer>
 
 
QgsImageCacheEntry::QgsImageCacheEntry( const QString &path, QSize size, const bool keepAspectRatio, const double opacity, double dpi )
  : QgsAbstractContentCacheEntry( path )
  , size( size )
  , keepAspectRatio( keepAspectRatio )
  , opacity( opacity )
  , targetDpi( dpi )
{
}
 
bool QgsImageCacheEntry::isEqual( const QgsAbstractContentCacheEntry *other ) const
{
  const QgsImageCacheEntry *otherImage = dynamic_cast< const QgsImageCacheEntry * >( other );
  // cheapest checks first!
  if ( !otherImage || otherImage->keepAspectRatio != keepAspectRatio || otherImage->size != size || ( !size.isValid() && otherImage->targetDpi != targetDpi ) || otherImage->opacity != opacity || otherImage->path != path )
    return false;
 
  return true;
}
 
int QgsImageCacheEntry::dataSize() const
{
  int size = 0;
  if ( !image.isNull() )
  {
    size += image.sizeInBytes();
  }
  return size;
}
 
void QgsImageCacheEntry::dump() const
{
  QgsDebugMsgLevel( QStringLiteral( "path: %1, size %2x%3" ).arg( path ).arg( size.width() ).arg( size.height() ), 3 );
}
 
 
static const int DEFAULT_IMAGE_CACHE_MAX_BYTES = 104857600;
 
QgsImageCache::QgsImageCache( QObject *parent )
  : QgsAbstractContentCache< QgsImageCacheEntry >( parent, QObject::tr( "Image" ),  DEFAULT_IMAGE_CACHE_MAX_BYTES )
{
  int bytes = QgsSettings().value( QStringLiteral( "/qgis/maxImageCacheSize" ), 0 ).toInt();
  if ( bytes > 0 )
  {
    mMaxCacheSize = bytes;
  }
 
  mMissingSvg = QStringLiteral( "<svg width='10' height='10'><text x='5' y='10' font-size='10' text-anchor='middle'>?</text></svg>" ).toLatin1();
 
  const QString downloadingSvgPath = QgsApplication::defaultThemePath() + QStringLiteral( "downloading_svg.svg" );
  if ( QFile::exists( downloadingSvgPath ) )
  {
    QFile file( downloadingSvgPath );
    if ( file.open( QIODevice::ReadOnly ) )
    {
      mFetchingSvg = file.readAll();
    }
  }
 
  if ( mFetchingSvg.isEmpty() )
  {
    mFetchingSvg = QStringLiteral( "<svg width='10' height='10'><text x='5' y='10' font-size='10' text-anchor='middle'>?</text></svg>" ).toLatin1();
  }
 
  connect( this, &QgsAbstractContentCacheBase::remoteContentFetched, this, &QgsImageCache::remoteImageFetched );
}
 
QImage QgsImageCache::pathAsImage( const QString &f, const QSize size, const bool keepAspectRatio, const double opacity, bool &fitsInCache, bool blocking, double targetDpi, bool *isMissing )
{
  const QString file = f.trimmed();
  if ( isMissing )
    *isMissing = true;
 
  if ( file.isEmpty() )
    return QImage();
 
  const QMutexLocker locker( &mMutex );
 
  fitsInCache = true;
 
  QgsImageCacheEntry *currentEntry = findExistingEntry( new QgsImageCacheEntry( file, size, keepAspectRatio, opacity, targetDpi ) );
 
  QImage result;
 
  //if current entry image is null: create the image
  // checks to see if image will fit into cache
  //update stats for memory usage
  if ( currentEntry->image.isNull() )
  {
    long cachedDataSize = 0;
    bool isBroken = false;
    result = renderImage( file, size, keepAspectRatio, opacity, targetDpi, isBroken, blocking );
    cachedDataSize += result.sizeInBytes();
    if ( cachedDataSize > mMaxCacheSize / 2 )
    {
      fitsInCache = false;
      currentEntry->image = QImage();
    }
    else
    {
      mTotalSize += result.sizeInBytes();
      currentEntry->image = result;
    }
 
    if ( isMissing )
      *isMissing = isBroken;
    currentEntry->isMissingImage = isBroken;
 
    trimToMaximumSize();
  }
  else
  {
    result = currentEntry->image;
    if ( isMissing )
      *isMissing = currentEntry->isMissingImage;
  }
 
  return result;
}
 
QSize QgsImageCache::originalSize( const QString &path, bool blocking ) const
{
  if ( path.isEmpty() )
    return QSize();
 
  // direct read if path is a file -- maybe more efficient than going the bytearray route? (untested!)
  if ( !path.startsWith( QLatin1String( "base64:" ) ) && QFile::exists( path ) )
  {
    const QImageReader reader( path );
    if ( reader.size().isValid() )
      return reader.size();
    else
      return QImage( path ).size();
  }
  else
  {
    QByteArray ba = getContent( path, QByteArray( "broken" ), QByteArray( "fetching" ), blocking );
 
    if ( ba != "broken" && ba != "fetching" )
    {
      QBuffer buffer( &ba );
      buffer.open( QIODevice::ReadOnly );
 
      QImageReader reader( &buffer );
      // if QImageReader::size works, then it's more efficient as it doesn't
      // read the whole image (see Qt docs)
      const QSize s = reader.size();
      if ( s.isValid() )
        return s;
      const QImage im = reader.read();
      return im.isNull() ? QSize() : im.size();
    }
  }
  return QSize();
}
 
QImage QgsImageCache::renderImage( const QString &path, QSize size, const bool keepAspectRatio, const double opacity, double targetDpi, bool &isBroken, bool blocking ) const
{
  QImage im;
  isBroken = false;
 
  // direct read if path is a file -- maybe more efficient than going the bytearray route? (untested!)
  if ( !path.startsWith( QLatin1String( "base64:" ) ) && QFile::exists( path ) )
  {
    QImageReader reader( path );
    reader.setAutoTransform( true );
 
    if ( reader.format() == "pdf" )
    {
      if ( !size.isEmpty() )
      {
        // special handling for this format -- we need to pass the desired target size onto the image reader
        // so that it can correctly render the (vector) pdf content at the desired dpi. Otherwise it returns
        // a very low resolution image (the driver assumes points == pixels!)
        // For other image formats, we read the original image size only and defer resampling to later in this
        // function. That gives us more control over the resampling method used.
        reader.setScaledSize( size );
      }
      else
      {
        // driver assumes points == pixels, so driver image size is reported assuming 72 dpi.
        const QSize sizeAt72Dpi = reader.size();
        const QSize sizeAtTargetDpi = sizeAt72Dpi * targetDpi / 72;
        reader.setScaledSize( sizeAtTargetDpi );
      }
    }
 
    im = reader.read();
  }
  else
  {
    QByteArray ba = getContent( path, QByteArray( "broken" ), QByteArray( "fetching" ), blocking );
 
    if ( ba == "broken" )
    {
      isBroken = true;
 
      // if the size parameter is not valid, skip drawing of missing image symbol
      if ( !size.isValid() )
        return im;
 
      // if image size is set to respect aspect ratio, correct for broken image aspect ratio
      if ( size.width() == 0 )
        size.setWidth( size.height() );
      if ( size.height() == 0 )
        size.setHeight( size.width() );
      // render "broken" svg
      im = QImage( size, QImage::Format_ARGB32_Premultiplied );
      im.fill( 0 ); // transparent background
 
      QPainter p( &im );
      QSvgRenderer r( mMissingSvg );
 
      QSizeF s( r.viewBox().size() );
      s.scale( size.width(), size.height(), Qt::KeepAspectRatio );
      const QRectF rect( ( size.width() - s.width() ) / 2, ( size.height() - s.height() ) / 2, s.width(), s.height() );
      r.render( &p, rect );
    }
    else if ( ba == "fetching" )
    {
      // if image size is set to respect aspect ratio, correct for broken image aspect ratio
      if ( size.width() == 0 )
        size.setWidth( size.height() );
      if ( size.height() == 0 )
        size.setHeight( size.width() );
 
      // render "fetching" svg
      im = QImage( size, QImage::Format_ARGB32_Premultiplied );
      im.fill( 0 ); // transparent background
 
      QPainter p( &im );
      QSvgRenderer r( mFetchingSvg );
 
      QSizeF s( r.viewBox().size() );
      s.scale( size.width(), size.height(), Qt::KeepAspectRatio );
      const QRectF rect( ( size.width() - s.width() ) / 2, ( size.height() - s.height() ) / 2, s.width(), s.height() );
      r.render( &p, rect );
    }
    else
    {
      QBuffer buffer( &ba );
      buffer.open( QIODevice::ReadOnly );
 
      QImageReader reader( &buffer );
      reader.setAutoTransform( true );
 
      if ( reader.format() == "pdf" )
      {
        if ( !size.isEmpty() )
        {
          // special handling for this format -- we need to pass the desired target size onto the image reader
          // so that it can correctly render the (vector) pdf content at the desired dpi. Otherwise it returns
          // a very low resolution image (the driver assumes points == pixels!)
          // For other image formats, we read the original image size only and defer resampling to later in this
          // function. That gives us more control over the resampling method used.
          reader.setScaledSize( size );
        }
        else
        {
          // driver assumes points == pixels, so driver image size is reported assuming 72 dpi.
          const QSize sizeAt72Dpi = reader.size();
          const QSize sizeAtTargetDpi = sizeAt72Dpi * targetDpi / 72;
          reader.setScaledSize( sizeAtTargetDpi );
        }
      }
 
      im = reader.read();
    }
  }
 
  if ( !im.hasAlphaChannel() )
    im = im.convertToFormat( QImage::Format_ARGB32 );
 
  if ( opacity < 1.0 )
    QgsImageOperation::multiplyOpacity( im, opacity );
 
  // render image at desired size -- null size means original size
  if ( !size.isValid() || size.isNull() || im.size() == size )
    return im;
  // when original aspect ratio is respected and provided height value is 0, automatically compute height
  else if ( keepAspectRatio && size.height() == 0 )
    return im.scaledToWidth( size.width(), Qt::SmoothTransformation );
  // when original aspect ratio is respected and provided width value is 0, automatically compute width
  else if ( keepAspectRatio && size.width() == 0 )
    return im.scaledToHeight( size.height(), Qt::SmoothTransformation );
  else
    return im.scaled( size, keepAspectRatio ? Qt::KeepAspectRatio : Qt::IgnoreAspectRatio, Qt::SmoothTransformation );
}