ImageF.cpp

// SPDX-License-Identifier: LGPL-2.1-or-later
//
// SPDX-FileCopyrightText: 2013 Adrian Draghici <[email protected]>
 
#include "ImageF.h"
 
namespace Marble {
 
ImageF::ImageF()
{
}
 
uint ImageF::pixelF( const QImage& image, qreal x, qreal y )
{
 
    const QRgb& topLeftPixel = image.pixel( (int) x, (int) y );
 
    // Bilinear interpolation to determine the color of a subpixel
 
    int iX = int( x );
    int iY = int( y );
 
    qreal fY = y - iY;
 
    // Interpolation in y-direction
    if ( ( iY + 1 ) < image.height() ) {
 
        QRgb bottomLeftPixel  =  image.pixel( iX, iY + 1 );
 
        // Blending the color values of the top left and bottom left point
        qreal ml_red   = ( 1.0 - fY ) * qRed  ( topLeftPixel  ) + fY * qRed  ( bottomLeftPixel  );
        qreal ml_green = ( 1.0 - fY ) * qGreen( topLeftPixel  ) + fY * qGreen( bottomLeftPixel  );
        qreal ml_blue  = ( 1.0 - fY ) * qBlue ( topLeftPixel  ) + fY * qBlue ( bottomLeftPixel  );
 
        // Interpolation in x-direction
        if ( iX + 1 < image.width() ) {
 
            qreal fX = x - iX;
 
            QRgb topRightPixel    =  image.pixel( iX + 1, iY );
            QRgb bottomRightPixel =  image.pixel( iX + 1, iY + 1 );
 
            // Blending the color values of the top right and bottom right point
            qreal mr_red   = ( 1.0 - fY ) * qRed  ( topRightPixel ) + fY * qRed  ( bottomRightPixel );
            qreal mr_green = ( 1.0 - fY ) * qGreen( topRightPixel ) + fY * qGreen( bottomRightPixel );
            qreal mr_blue  = ( 1.0 - fY ) * qBlue ( topRightPixel ) + fY * qBlue ( bottomRightPixel );
 
            // Blending the color values of the resulting middle left and middle right points
            int mm_red   = int( ( ( 1.0 - fX ) * ml_red   + fX * mr_red   ) );
            int mm_green = int( ( ( 1.0 - fX ) * ml_green + fX * mr_green ) );
            int mm_blue  = int( ( ( 1.0 - fX ) * ml_blue  + fX * mr_blue  ) );
 
            return qRgb( mm_red, mm_green, mm_blue );
        }
        else {
            return qRgb( ml_red, ml_green, ml_blue );
        }
    }
    else {
        // Interpolation in x-direction
        if ( iX + 1 < image.width() ) {
 
            qreal fX = x - iX;
 
            if ( fX == 0.0 )
                return topLeftPixel;
 
            QRgb topRightPixel    =  image.pixel( iX + 1, iY );
 
            // Blending the color values of the top left and top right point
            int tm_red   = int( ( ( 1.0 - fX ) * qRed  ( topLeftPixel ) + fX * qRed  ( topRightPixel ) ) );
            int tm_green = int( ( ( 1.0 - fX ) * qGreen( topLeftPixel ) + fX * qGreen( topRightPixel ) ) );
            int tm_blue  = int( ( ( 1.0 - fX ) * qBlue ( topLeftPixel ) + fX * qBlue ( topRightPixel ) ) );
 
            return qRgb( tm_red, tm_green, tm_blue );
        }
    }
 
    return topLeftPixel;
}
 
}