inline void boost::gil::rescale_rows(const SrcView& src, const DstView& dst, const Filter& filter)
{
typedef typename SrcView::value_type src_pixel_t;
typedef typename gil::detail::create_accum_pixel_type<src_pixel_t>::type accum_pixel_t;
if (src.width() != dst.width())
{
throw std::runtime_error("rescale_rows: width of source and destination views must match");
}
detail::weight_table weights;
weights.reset(filter, src.height(), dst.height());
detail::weight_table::const_iterator const table_begin = weights.begin();
detail::weight_table::const_iterator const table_end = weights.end();
typedef typename DstView::coord_t coord_t;
coord_t const width = dst.width();
for (coord_t x=0; x<width; x++)
{
detail::rescale_line<accum_pixel_t>(
src.col_begin(x)
, dst.col_begin(x)
, table_begin
, table_end
);
}
}
inline void boost::gil::rescale(const SrcView& src, const DstView& dst, const Filter& filter)
{
typedef typename SrcView::value_type src_pixel_t;
typedef typename gil::detail::create_accum_pixel_type<src_pixel_t>::type accum_pixel_t;
// construct weights tables
detail::weight_table horizontal_weights;
horizontal_weights.reset(filter, src.width(), dst.width());
detail::weight_table vertical_weights;
vertical_weights.reset(filter, src.height(), dst.height());
// allocate intermediary pixels row
std::vector<accum_pixel_t> intermediate_row( src.width() );
typedef typename DstView::coord_t coord_t;
coord_t const src_width = src.width();
coord_t const dst_height = dst.height();
for (coord_t y=0; y<dst_height; y++)
{
// create the intermediate row by vertically sampling the source image pixels
detail::weight_table::const_iterator const vtable_begin = vertical_weights.begin() + y;
detail::weight_table::const_iterator const vtable_end = vtable_begin + 1;
for (coord_t x=0; x<src_width; x++)
{
detail::rescale_line<accum_pixel_t>(
src.col_begin(x)
, intermediate_row.begin() + x
, vtable_begin
, vtable_end
);
}
// scale horizontally the intermediate row into the destination row
detail::weight_table::const_iterator const htable_begin = horizontal_weights.begin();
detail::weight_table::const_iterator const htable_end = horizontal_weights.end();
detail::rescale_line<accum_pixel_t>(
intermediate_row.begin()
, dst.row_begin(y)
, htable_begin
, htable_end
);
}
}