161 lines
5.8 KiB
C
161 lines
5.8 KiB
C
/*
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* uPNG -- derived from LodePNG version 20100808
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*
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* Copyright (c) 2005-2010 Lode Vandevenne
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* Copyright (c) 2010 Sean Middleditch
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* Copyright (c) 2021-2022 Andy Green <andy@warmcat.com>
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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*
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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*
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* 3. This notice may not be removed or altered from any source
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* distribution.
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*
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* The above notice is the ZLIB license, libpng also uses it.
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*
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* This version is based on upng project's fork of lodepng and rewritten for
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* lws, changing the whole approach to decode on demand to issue a line of
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* output at a time, statefully.
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*/
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typedef enum lws_upng_format_t {
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LWS_UPNG_BADFORMAT,
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LWS_UPNG_RGB8,
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LWS_UPNG_RGB16,
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LWS_UPNG_RGBA8,
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LWS_UPNG_RGBA16,
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LWS_UPNG_LUMINANCE1,
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LWS_UPNG_LUMINANCE2,
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LWS_UPNG_LUMINANCE4,
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LWS_UPNG_LUMINANCE8,
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LWS_UPNG_LUMINANCE_ALPHA1,
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LWS_UPNG_LUMINANCE_ALPHA2,
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LWS_UPNG_LUMINANCE_ALPHA4,
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LWS_UPNG_LUMINANCE_ALPHA8
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} lws_upng_format_t;
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struct inflator_ctx;
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typedef struct lws_upng_t lws_upng_t;
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/**
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* lws_upng_new() - Create new UPNG decode object
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*
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* Returns a new PNG decoding object, which should be destroyed with
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* lws_upng_free() when done with, or NULL if OOM.
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*/
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LWS_VISIBLE LWS_EXTERN lws_upng_t *
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lws_upng_new(void);
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/**
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* lws_upng_free() - Destroy a PNG decode object
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*
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* \param upng: Pointer to the decode object to destroy and set to NULL
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*
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* This also frees any sub-allocations in the object.
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*/
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LWS_VISIBLE LWS_EXTERN void
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lws_upng_free(lws_upng_t **upng);
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/**
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* lws_upng_emit_next_line() - deocde the next line
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*
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* \param upng: the decode object
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* \param ppix: pointer to a pointer set to the line's decoded pixel data
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* \param buf: pointer to a const uint8_t array of PNG input
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* \param size: pointer to the count of bytes available at *buf
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* \param hold_at_metadata: true if we should not advance to decode
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*
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* Make PNG input available to the decoder so it can issue the next line's
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* worth of pixels. If the call consumed any input, *buf and *size are
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* adjusted accordingly.
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*
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* The decoder is stateful so it is not sensitive to the chunk size for the
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* input.
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*
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* If \p hold_at_metadata is set, then the decoder will only go as far as
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* picking out the metadata like image dimensions, but not start the decode,
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* which requires the >30KB heap allocation. This lets you put off for as long
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* as possible committing to the decode allocation... this only helps overall
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* if you have flow controlled the incoming PNG data.
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*
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* Return will be one of LWS_SRET_WANT_INPUT is the decoder is stalled waiting
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* for more input to be provided, LWS_SRET_WANT_OUTPUT is the decoder stopped
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* because it had produced a whole line of output pixels (which can be found
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* starting at *ppix), LWS_SRET_OK is it completed and LWS_SRET_FATAL or larger
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* if the decode failed.
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*/
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LWS_VISIBLE LWS_EXTERN lws_stateful_ret_t
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lws_upng_emit_next_line(lws_upng_t *upng, const uint8_t **ppix,
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const uint8_t **buf, size_t *size,
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char hold_at_metadata);
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LWS_VISIBLE LWS_EXTERN unsigned int
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lws_upng_get_width(const lws_upng_t *upng);
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LWS_VISIBLE LWS_EXTERN unsigned int
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lws_upng_get_height(const lws_upng_t *upng);
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LWS_VISIBLE LWS_EXTERN unsigned int
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lws_upng_get_bpp(const lws_upng_t *upng);
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LWS_VISIBLE LWS_EXTERN unsigned int
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lws_upng_get_bitdepth(const lws_upng_t *upng);
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LWS_VISIBLE LWS_EXTERN unsigned int
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lws_upng_get_components(const lws_upng_t *upng);
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LWS_VISIBLE LWS_EXTERN unsigned int
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lws_upng_get_pixelsize(const lws_upng_t *upng);
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LWS_VISIBLE LWS_EXTERN lws_upng_format_t
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lws_upng_get_format(const lws_upng_t *upng);
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/**
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* lws_upng_inflator_create() - create a gzip inflator context
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*
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* \param outring: pointer set to the output ringbuffer on exit
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* \param outringlen: size of the output ringbuffer set on exit
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* \param opl: pointer to set to point to ctx outpos_linear
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* \param cl: pointer to set to point to ctx consumed_linear
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*
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* Creates an opaque gzip inflator object.
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*/
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LWS_VISIBLE LWS_EXTERN struct inflator_ctx *
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lws_upng_inflator_create(const uint8_t **outring, size_t *outringlen,
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size_t **opl, size_t **cl);
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/**
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* lws_upng_inflate_data() - inflate compressed data statefully
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*
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* \param inf: inflator context created with lws_upng_inflator_create()
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* \param buf: NULL to continue consumption of existing input, or new input
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* \param len: ignored if \p buf is NULL, else amount of new input at \p buf
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*
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* Tries to progress the inflation. If output is available, \p *opl will be
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* further along than before it was called. \p *cl should be set to \p opl
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* to consume the available output data.
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*
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* Output is into a ringfuffer, typically sized at 32KB. \p opl and \p cl
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* are "linear", that is extend beyond the ringbuffer. They should be modulo
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* outringlen (given when the inflator was created) when accessing outring.
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*/
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LWS_VISIBLE LWS_EXTERN lws_stateful_ret_t
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lws_upng_inflate_data(struct inflator_ctx *inf, const void *buf, size_t len);
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/**
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* lws_upng_inflator_destroy() - destroys the inflation context and ringbuffer
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*
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* \p inf: pointer to pointer to inflation context
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*
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* Frees the inflation context and its allocations, and sets \p *inf to NULL.
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*/
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LWS_VISIBLE LWS_EXTERN void
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lws_upng_inflator_destroy(struct inflator_ctx **inf);
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