private function _projectSourceOnCanvas(&$source, &$canvas) {
        $srcX = 0;
        $srcY = 0;
        list($projectionWidth, $projectionHeight) = $this->_getProjectionSize();
        list($destX, $destY) = $this->_getLeftUpperCoordinateOnCanvas(
            $projectionWidth,
            $projectionHeight
        );
        imagecopyresampled(
            $canvas,
            $source,
            $destX,
            $destY,
            $srcX,
            $srcY,
            $projectionWidth,
            $projectionHeight,
            $this->_params['sourceWidth'],
            $this->_params['sourceHeight']
        );
    }