124 lines
5.5 KiB
C++
124 lines
5.5 KiB
C++
/*
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BMP File Reader/Writer Implementation
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Anton Gerdelan
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Version: 3.1 18 March 2020.
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Licence: see bottom of file.
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C89 ( Implementation is C99 )
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Contributors:
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- Anton Gerdelan - Initial code.
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- Saija Sorsa - Fuzz testing.
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Instructions:
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- Just drop this header, and the matching .c file into your project.
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- To get debug printouts during parsing define APG_BMP_DEBUG_OUTPUT.
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Advantages:
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- The implementation is fast, simple, and supports more formats than most BMP reader libraries.
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- The reader function is fuzzed with AFL https://lcamtuf.coredump.cx/afl/.
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- The reader is robust to large files and malformed files, and will return any valid partial data in an image.
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- Reader supports 32bpp (with alpha channel), 24bpp, 8bpp, 4bpp, and 1bpp monochrome BMP images.
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- Reader handles indexed BMP images using a colour palette.
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- Writer supports 32bpp RGBA and 24bpp uncompressed RGB images.
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Current Limitations:
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- 16-bit images not supported (don't have any samples to test on).
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- No support for interleaved channel bit layouts eg RGB101010 RGB555 RGB565.
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- No support for compressed BMP images, although in practice these are not used.
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- Output images with alpha channel are written in BITMAPINFOHEADER format.
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For better alpha support in other apps the 124-bit v5 header could be used instead,
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at the cost of some backward compatibility and bloat.
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To Do:
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- FUZZING
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- create a unique fuzz test set for (8,4,1 BPP).
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- (maybe) FEATURE Flipping the image based on negative width and height in header, and/or function arguments.
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- (maybe) PERF ifdef intrinsics/asm for bitscan. Platform-specific code so won't include unless necessary.
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- (maybe) FEATURE Add parameter for padding output memory to eg 4-byte alignment or n channels.
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- (maybe) FEATURE Improved apps support in alpha channel writing (using v5 header).
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*/
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#ifndef APG_BMP_H_
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#define APG_BMP_H_
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#ifdef __cplusplus
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extern "C" {
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#endif /* CPP */
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/* Reads a bitmap from a file, allocates memory for the raw image data, and returns it.
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PARAMS
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* w,h, - Retrieves the width and height of the BMP in pixels.
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* n_chans - Retrieves the number of channels in the BMP.
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RETURNS
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* Tightly-packed pixel memory in RGBA order. The caller must call free() on the memory.
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* NULL on any error. Any allocated memory is freed before returning NULL. */
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unsigned char* apg_bmp_read( const char* filename, int* w, int* h, unsigned int* n_chans );
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/* Calls free() on memory created by apg_bmp_read */
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void apg_bmp_free( unsigned char* pixels_ptr );
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/* Writes a bitmap to a file.
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PARAMS
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* filename - e.g."my_bitmap.bmp". Must not be NULL.
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* pixels_ptr - Pointer to tightly-packed pixel memory in RGBA order. Must not be NULL. There must be abs(w)*abs(h)*n_chans bytes in the memory pointed to.
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* w,h, - Width and height of the image in pixels.
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* n_chans - The number of channels in the BMP. 3 or 4 supported for writing, which means RGB or RGBA memory, respectively.
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RETURNS
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* Zero on any error, non zero on success. */
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unsigned int apg_bmp_write( const char* filename, unsigned char* pixels_ptr, int w, int h, unsigned int n_chans );
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#ifdef __cplusplus
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}
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#endif /* CPP */
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#endif /*_APG_BMP_H_ */
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/*
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-------------------------------------------------------------------------------------
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This software is available under two licences - you may use it under either licence.
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-------------------------------------------------------------------------------------
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FIRST LICENCE OPTION
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> Apache License
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> Version 2.0, January 2004
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> http://www.apache.org/licenses/
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> Copyright 2019 Anton Gerdelan.
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> Licensed under the Apache License, Version 2.0 (the "License");
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> you may not use this file except in compliance with the License.
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> You may obtain a copy of the License at
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> http://www.apache.org/licenses/LICENSE-2.0
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> Unless required by applicable law or agreed to in writing, software
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> distributed under the License is distributed on an "AS IS" BASIS,
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> WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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> See the License for the specific language governing permissions and
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> limitations under the License.
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-------------------------------------------------------------------------------------
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SECOND LICENCE OPTION
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> This is free and unencumbered software released into the public domain.
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>
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> Anyone is free to copy, modify, publish, use, compile, sell, or
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> distribute this software, either in source code form or as a compiled
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> binary, for any purpose, commercial or non-commercial, and by any
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> means.
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>
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> In jurisdictions that recognize copyright laws, the author or authors
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> of this software dedicate any and all copyright interest in the
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> software to the public domain. We make this dedication for the benefit
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> of the public at large and to the detriment of our heirs and
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> successors. We intend this dedication to be an overt act of
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> relinquishment in perpetuity of all present and future rights to this
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> software under copyright law.
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>
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> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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> EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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> MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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> IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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> OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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> ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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> OTHER DEALINGS IN THE SOFTWARE.
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>
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> For more information, please refer to <http://unlicense.org>
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-------------------------------------------------------------------------------------
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*/
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