86 lines
3.7 KiB
C++
86 lines
3.7 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2024 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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#ifndef MAPNIK_CAIRO_IMAGE_UTIL_HPP
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#define MAPNIK_CAIRO_IMAGE_UTIL_HPP
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// mapnik
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#include <mapnik/image.hpp>
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#include <mapnik/cairo/cairo_context.hpp> // for cairo_surface_ptr
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// stl
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#include <stdexcept>
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namespace mapnik {
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static inline void cairo_image_to_rgba8(mapnik::image_rgba8& data, cairo_surface_ptr const& surface)
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{
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if (cairo_image_surface_get_format(&*surface) != CAIRO_FORMAT_ARGB32)
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{
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throw std::runtime_error("Unable to convert this Cairo format to rgba8 image");
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}
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if (cairo_image_surface_get_width(&*surface) != static_cast<int>(data.width()) ||
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cairo_image_surface_get_height(&*surface) != static_cast<int>(data.height()))
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{
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throw std::runtime_error("Mismatch in dimensions: size of image must match side of cairo surface");
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}
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int stride = cairo_image_surface_get_stride(&*surface) / 4;
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const std::unique_ptr<unsigned int[]> out_row(new unsigned int[data.width()]);
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const unsigned int* in_row = (const unsigned int*)cairo_image_surface_get_data(&*surface);
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for (unsigned int row = 0; row < data.height(); row++, in_row += stride)
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{
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for (unsigned int column = 0; column < data.width(); column++)
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{
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unsigned int in = in_row[column];
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unsigned int a = (in >> 24) & 0xff;
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unsigned int r = (in >> 16) & 0xff;
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unsigned int g = (in >> 8) & 0xff;
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unsigned int b = (in >> 0) & 0xff;
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#define DE_ALPHA(x) \
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do \
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{ \
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if (a == 0) \
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x = 0; \
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else \
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x = x * 255 / a; \
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if (x > 255) \
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x = 255; \
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} while (0)
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DE_ALPHA(r);
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DE_ALPHA(g);
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DE_ALPHA(b);
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out_row[column] = color(r, g, b, a).rgba();
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}
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data.set_row(row, out_row.get(), data.width());
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}
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}
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} // namespace mapnik
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#endif // MAPNIK_CAIRO_IMAGE_UTIL_HPP
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