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Add a simple PNG image encoder with Lua API (#11485)
* Add a simple PNG image encoder with Lua API Add ColorSpec to RGBA converter Make a safety wrapper for the encoder Create devtest examples Co-authored-by: hecktest <> Co-authored-by: sfan5 <sfan5@live.de>
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/* | ||
Minetest | ||
Copyright (C) 2021 hecks | ||
This program is free software; you can redistribute it and/or modify | ||
it under the terms of the GNU Lesser General Public License as published by | ||
the Free Software Foundation; either version 2.1 of the License, or | ||
(at your option) any later version. | ||
This program is distributed in the hope that it will be useful, | ||
but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
GNU Lesser General Public License for more details. | ||
You should have received a copy of the GNU Lesser General Public License along | ||
with this program; if not, write to the Free Software Foundation, Inc., | ||
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | ||
*/ | ||
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#include "png.h" | ||
#include <string> | ||
#include <sstream> | ||
#include <zlib.h> | ||
#include <cassert> | ||
#include "util/serialize.h" | ||
#include "serialization.h" | ||
#include "irrlichttypes.h" | ||
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static void writeChunk(std::ostringstream &target, const std::string &chunk_str) | ||
{ | ||
assert(chunk_str.size() >= 4); | ||
assert(chunk_str.size() - 4 < U32_MAX); | ||
writeU32(target, chunk_str.size() - 4); // Write length minus the identifier | ||
target << chunk_str; | ||
writeU32(target, crc32(0,(const u8*)chunk_str.data(), chunk_str.size())); | ||
} | ||
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std::string encodePNG(const u8 *data, u32 width, u32 height, s32 compression) | ||
{ | ||
auto file = std::ostringstream(std::ios::binary); | ||
file << "\x89PNG\r\n\x1a\n"; | ||
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{ | ||
auto IHDR = std::ostringstream(std::ios::binary); | ||
IHDR << "IHDR"; | ||
writeU32(IHDR, width); | ||
writeU32(IHDR, height); | ||
// 8 bpp, color type 6 (RGBA) | ||
IHDR.write("\x08\x06\x00\x00\x00", 5); | ||
writeChunk(file, IHDR.str()); | ||
} | ||
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{ | ||
auto IDAT = std::ostringstream(std::ios::binary); | ||
IDAT << "IDAT"; | ||
auto scanlines = std::ostringstream(std::ios::binary); | ||
for(u32 i = 0; i < height; i++) { | ||
scanlines.write("\x00", 1); // Null predictor | ||
scanlines.write((const char*) data + width * 4 * i, width * 4); | ||
} | ||
compressZlib(scanlines.str(), IDAT, compression); | ||
writeChunk(file, IDAT.str()); | ||
} | ||
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file.write("\x00\x00\x00\x00IEND\xae\x42\x60\x82", 12); | ||
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return file.str(); | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,27 @@ | ||
/* | ||
Minetest | ||
Copyright (C) 2021 hecks | ||
This program is free software; you can redistribute it and/or modify | ||
it under the terms of the GNU Lesser General Public License as published by | ||
the Free Software Foundation; either version 2.1 of the License, or | ||
(at your option) any later version. | ||
This program is distributed in the hope that it will be useful, | ||
but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
GNU Lesser General Public License for more details. | ||
You should have received a copy of the GNU Lesser General Public License along | ||
with this program; if not, write to the Free Software Foundation, Inc., | ||
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | ||
*/ | ||
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#pragma once | ||
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#include <string> | ||
#include "irrlichttypes.h" | ||
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/* Simple PNG encoder. Encodes an RGBA image with no predictors. | ||
Returns a binary string. */ | ||
std::string encodePNG(const u8 *data, u32 width, u32 height, s32 compression); |
Should be
error("Incorrect type for 'data', expected table or string, got " .. type(data))