qgsrasteriterator.cpp

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/***************************************************************************
    qgsrasteriterator.cpp
    ---------------------
    begin                : July 2012
    copyright            : (C) 2012 by Marco Hugentobler
    email                : marco dot hugentobler at sourcepole dot ch
 ***************************************************************************
 *                                                                         *
 *   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 "qgsrasteriterator.h"
#include "qgsrasterinterface.h"
#include "qgsrasterdataprovider.h"
 
QgsRasterIterator::QgsRasterIterator( QgsRasterInterface *input, int tileOverlapPixels )
  : mInput( input )
  , mTileOverlapPixels( tileOverlapPixels )
  , mMaximumTileWidth( DEFAULT_MAXIMUM_TILE_WIDTH )
  , mMaximumTileHeight( DEFAULT_MAXIMUM_TILE_HEIGHT )
{
  for ( QgsRasterInterface *ri = input; ri; ri = ri->input() )
  {
    QgsRasterDataProvider *rdp = dynamic_cast<QgsRasterDataProvider *>( ri );
    if ( rdp )
    {
      mMaximumTileWidth = rdp->stepWidth() - 2 * mTileOverlapPixels;
      mMaximumTileHeight = rdp->stepHeight() - 2 * mTileOverlapPixels;
      break;
    }
  }
}
 
QgsRectangle QgsRasterIterator::subRegion( const QgsRectangle &rasterExtent, int rasterWidth, int rasterHeight, const QgsRectangle &subRegion, int &subRegionWidth, int &subRegionHeight, int &subRegionLeft, int &subRegionTop )
{
  const double xRes = rasterExtent.width() / rasterWidth;
  const double yRes = rasterExtent.height() / rasterHeight;
 
  int top = 0;
  int bottom = rasterHeight - 1;
  int left = 0;
  int right = rasterWidth - 1;
 
  if ( subRegion.yMaximum() < rasterExtent.yMaximum() )
  {
    top = static_cast< int >( std::floor( ( rasterExtent.yMaximum() - subRegion.yMaximum() ) / yRes ) );
  }
  if ( subRegion.yMinimum() > rasterExtent.yMinimum() )
  {
    bottom = static_cast< int >( std::ceil( ( rasterExtent.yMaximum() - subRegion.yMinimum() ) / yRes ) - 1 );
  }
 
  if ( subRegion.xMinimum() > rasterExtent.xMinimum() )
  {
    left = static_cast< int >( std::floor( ( subRegion.xMinimum() - rasterExtent.xMinimum() ) / xRes ) );
  }
  if ( subRegion.xMaximum() < rasterExtent.xMaximum() )
  {
    right = static_cast< int >( std::ceil( ( subRegion.xMaximum() - rasterExtent.xMinimum() ) / xRes ) - 1 );
  }
 
  subRegionWidth = right - left + 1;
  subRegionHeight = bottom - top + 1;
  subRegionLeft = left;
  subRegionTop = top;
 
  return QgsRectangle( rasterExtent.xMinimum() + ( left * xRes ),
                       rasterExtent.yMaximum() - ( ( top + subRegionHeight ) * yRes ),
                       rasterExtent.xMinimum() + ( ( left + subRegionWidth ) * xRes ),
                       rasterExtent.yMaximum() - ( top * yRes ) );
}
 
void QgsRasterIterator::startRasterRead( int bandNumber, qgssize nCols, qgssize nRows, const QgsRectangle &extent, QgsRasterBlockFeedback *feedback )
{
  if ( !mInput )
  {
    return;
  }
 
  mExtent = extent;
  mFeedback = feedback;
 
  //remove any previous part on that band
  removePartInfo( bandNumber );
 
  //split raster into small portions if necessary
  RasterPartInfo pInfo;
  pInfo.nCols = nCols;
  pInfo.nRows = nRows;
  pInfo.currentCol = 0;
  pInfo.currentRow = 0;
  mRasterPartInfos.insert( bandNumber, pInfo );
}
 
bool QgsRasterIterator::next( int bandNumber, int &columns, int &rows, int &topLeftColumn, int &topLeftRow, QgsRectangle &blockExtent )
{
  int outTileColumns = 0;
  int outTileRows = 0;
  int outTileTopLeftColumn = 0;
  int outTileTopLeftRow = 0;
  return readNextRasterPartInternal( bandNumber, columns, rows, nullptr, topLeftColumn, topLeftRow, &blockExtent, outTileColumns, outTileRows, outTileTopLeftColumn, outTileTopLeftRow );
}
 
bool QgsRasterIterator::readNextRasterPart( int bandNumber,
    int &nCols, int &nRows,
    QgsRasterBlock **block,
    int &topLeftCol, int &topLeftRow )
{
  *block = nullptr;
  std::unique_ptr< QgsRasterBlock > nextBlock;
  const bool result = readNextRasterPart( bandNumber, nCols, nRows, nextBlock, topLeftCol, topLeftRow );
  if ( result )
    *block = nextBlock.release();
  return result;
}
 
bool QgsRasterIterator::readNextRasterPart( int bandNumber, int &nCols, int &nRows, std::unique_ptr<QgsRasterBlock> &block, int &topLeftCol, int &topLeftRow, QgsRectangle *blockExtent, int *tileColumns, int *tileRows, int *tileTopLeftColumn, int *tileTopLeftRow )
{
  int outTileColumns = 0;
  int outTileRows = 0;
  int outTileTopLeftColumn = 0;
  int outTileTopLeftRow = 0;
  const bool res = readNextRasterPartInternal( bandNumber, nCols, nRows, &block, topLeftCol, topLeftRow, blockExtent, outTileColumns, outTileRows, outTileTopLeftColumn, outTileTopLeftRow );
 
  if ( tileColumns )
    *tileColumns = outTileColumns;
  if ( tileRows )
    *tileRows = outTileRows;
  if ( tileTopLeftColumn )
    *tileTopLeftColumn = outTileTopLeftColumn;
  if ( tileTopLeftRow )
    *tileTopLeftRow = outTileTopLeftRow;
 
  return res;
}
 
bool QgsRasterIterator::readNextRasterPartInternal( int bandNumber, int &nCols, int &nRows, std::unique_ptr<QgsRasterBlock> *block, int &topLeftCol, int &topLeftRow, QgsRectangle *blockExtent, int &tileColumns, int &tileRows, int &tileTopLeftColumn, int &tileTopLeftRow )
{
  QgsDebugMsgLevel( QStringLiteral( "Entered" ), 4 );
  if ( block )
    block->reset();
  //get partinfo
  const QMap<int, RasterPartInfo>::iterator partIt = mRasterPartInfos.find( bandNumber );
  if ( partIt == mRasterPartInfos.end() )
  {
    return false;
  }
 
  RasterPartInfo &pInfo = partIt.value();
 
  // If we started with zero cols or zero rows, just return (avoids divide by zero below)
  if ( 0 == pInfo.nCols || 0 == pInfo.nRows )
  {
    return false;
  }
 
  //remove last data block
 
  //already at end
  if ( pInfo.currentCol == pInfo.nCols && pInfo.currentRow == pInfo.nRows )
  {
    return false;
  }
 
  //read data block
 
  tileTopLeftColumn = pInfo.currentCol;
  tileTopLeftRow = pInfo.currentRow;
  tileColumns = static_cast< int >( std::min( static_cast< qgssize >( mMaximumTileWidth ), pInfo.nCols - tileTopLeftColumn ) );
  tileRows = static_cast< int >( std::min( static_cast< qgssize >( mMaximumTileHeight ), pInfo.nRows - tileTopLeftRow ) );
  const qgssize tileRight = tileTopLeftColumn + tileColumns;
  const qgssize tileBottom = tileTopLeftRow + tileRows;
 
  const qgssize blockLeft = tileTopLeftColumn >= mTileOverlapPixels ? ( tileTopLeftColumn - mTileOverlapPixels ) : 0;
  const qgssize blockTop = tileTopLeftRow >= mTileOverlapPixels ? ( tileTopLeftRow - mTileOverlapPixels ) : 0;
  const qgssize blockRight = std::min< qgssize >( tileRight + mTileOverlapPixels, pInfo.nCols );
  const qgssize blockBottom = std::min< qgssize >( tileBottom + mTileOverlapPixels, pInfo.nRows );
 
  nCols = blockRight - blockLeft;
  nRows = blockBottom - blockTop;
 
  QgsDebugMsgLevel( QStringLiteral( "nCols = %1 nRows = %2" ).arg( nCols ).arg( nRows ), 4 );
 
  //get subrectangle
  const QgsRectangle viewPortExtent = mExtent;
  const double xmin = viewPortExtent.xMinimum() + blockLeft / static_cast< double >( pInfo.nCols ) * viewPortExtent.width();
  const double xmax = blockLeft + nCols == pInfo.nCols ? viewPortExtent.xMaximum() :  // avoid extra FP math if not necessary
                      viewPortExtent.xMinimum() + ( blockLeft + nCols ) / static_cast< double >( pInfo.nCols ) * viewPortExtent.width();
  const double ymin = blockTop + nRows == pInfo.nRows ? viewPortExtent.yMinimum() :  // avoid extra FP math if not necessary
                      viewPortExtent.yMaximum() - ( blockTop + nRows ) / static_cast< double >( pInfo.nRows ) * viewPortExtent.height();
  const double ymax = viewPortExtent.yMaximum() - blockTop / static_cast< double >( pInfo.nRows ) * viewPortExtent.height();
  const QgsRectangle blockRect( xmin, ymin, xmax, ymax );
 
  if ( blockExtent )
    *blockExtent = blockRect;
 
  if ( block )
    block->reset( mInput->block( bandNumber, blockRect, nCols, nRows, mFeedback ) );
  topLeftCol = blockLeft;
  topLeftRow = blockTop;
 
  pInfo.currentCol = tileRight;
  if ( pInfo.currentCol == pInfo.nCols && tileBottom == pInfo.nRows ) //end of raster
  {
    pInfo.currentRow = pInfo.nRows;
  }
  else if ( pInfo.currentCol == pInfo.nCols ) //start new row
  {
    pInfo.currentCol = 0;
    pInfo.currentRow = tileBottom;
  }
 
  return true;
}
 
void QgsRasterIterator::stopRasterRead( int bandNumber )
{
  removePartInfo( bandNumber );
}
 
void QgsRasterIterator::removePartInfo( int bandNumber )
{
  const auto partIt = mRasterPartInfos.constFind( bandNumber );
  if ( partIt != mRasterPartInfos.constEnd() )
  {
    mRasterPartInfos.remove( bandNumber );
  }
}