diff options
Diffstat (limited to 'liblss16.h')
| -rw-r--r-- | liblss16.h | 150 |
1 files changed, 147 insertions, 3 deletions
@@ -104,6 +104,51 @@ enum liblss16_decode_error { /** + * Image encoding state + */ +enum liblss16_encode_state { + /** + * Still encoding + */ + LIBLSS16_ENCODE_RUNNING, + + /** + * Encodig done + */ + LIBLSS16_ENCODE_DONE, + + /** + * Error occured while encoding + */ + LIBLSS16_ENCODE_ERROR +}; + + +/** + * Error values for image encoding + */ +enum liblss16_encode_error { + /** + * The image has zero width, zero height, + * or the height exceeds 32767 + */ + LIBLSS16_ENCODE_BAD_IMAGE_SIZE, + + /** + * User specified that colour were encoded in + * 6 bits, however at least one colour value + * had at least one of it it high bits set + */ + LIBLSS16_ENCODE_BAD_COLOUR, + + /** + * Colour index above 15 specified for a pixel + */ + LIBLSS16_ENCODE_BAD_COLOUR_INDEX +}; + + +/** * sRGB colour values, with transfer function applied, * encoded in values in [0, 255] */ @@ -126,9 +171,9 @@ struct liblss16_colour { /** - * Decode state + * Image header */ -struct liblss16_decoder { +struct liblss16_header { /** * The width of the raster */ @@ -143,7 +188,17 @@ struct liblss16_decoder { * Image colour map */ struct liblss16_colour colour_map[16]; +}; + +/** + * Decode state + */ +struct liblss16_decoder { + /** + * Image header + */ + struct liblss16_header image; /** * For internal use @@ -161,6 +216,23 @@ struct liblss16_decoder { /** + * Encode state + * + * Should be considered opaque + */ +struct liblss16_encoder { + struct liblss16_header header; + uint16_t x_rem; + uint16_t y_rem; + uint16_t repetition; + uint8_t header_position; + uint8_t previous; + uint8_t nbuffered; + uint8_t buffered[6]; +}; + + +/** * Initialise a decoder * * @param decoder The decoder @@ -169,6 +241,8 @@ void liblss16_decoder_init(struct liblss16_decoder *decoder); /** + * Decode an LSS16 file + * * @param decoder Decoder state, must have been initialised with * `liblss16_decoder_init` before the first call * @param data Data to decode image from (may be partial) @@ -179,7 +253,8 @@ void liblss16_decoder_init(struct liblss16_decoder *decoder); * for the pixels in the image. They are returned * primarily from to the top down and secondarily * from left to right. - * @param pixels_size The number of elements that may be stored in `pixels` + * @param pixels_size The number of elements that may be stored in `pixels`, + * must be at least 1 * @param npixels_out Output parameter for the number of elements stored * in `pixels`. Always set. * @param error_out Output parameter for the error; only set if @@ -213,4 +288,73 @@ __attribute__((__const__)) const char *liblss16_decode_strerror(enum liblss16_decode_error error); +/** + * Initialise an encoder + * + * @param encoder The encoder + * @param header Image information + * @param rgb6 If non-zero, colour values in `header->colour_map` are + * encoded in 6 bits (the limitation of the LSS16 format) + * rather than 8 bits + * @param error_out Output parameter for the error; only set when -1 is + * returned; may be `NULL` + * @return 0 on success, -1 on failure + */ +int liblss16_encoder_init(struct liblss16_encoder *encoder, const struct liblss16_header *header, + int rgb6, enum liblss16_encode_error *error_out); + + +/** + * Encode an LSS16 file + * + * @param encoder Encoder state, must have been initialised with + * `liblss16_encoder_init` before the first call + * @param buffer Output buffer for the image data + * @param size Size of `buffer` + * @param written_out The number of bytes written to `size`, must be at least 1 + * @param pixels Buffer with pixels to encode; the pixels are to preencoded + * (before the function is called) with the colour index of + * each pixel. Pixels are input primarily from to the top + * down and secondarily from left to right. + * @param npixels The number of provided pixels + * @param nconsumed_out Output parameter for the number of pixels consumed into + * to state of the encoder + * @param error_out Output parameter for the error; only set if + * `LIBLSS16_ENCODE_ERROR` is returned; may be `NULL` + * @return The processing state: normally `LIBLSS16_ENCODE_RUNNING`, + * but `LIBLSS16_ENCODE_DONE` when the image has been + * fully encoded, and `LIBLSS16_ENCODE_ERROR` on error + */ +enum liblss16_encode_state liblss16_encode_from_colour_index( + struct liblss16_encoder *encoder, void *buffer, size_t size, + size_t *written_out, const uint8_t *pixels, size_t npixels, + size_t *nconsumed_out, enum liblss16_encode_error *error_out); + + +/** + * Get error description for an error code + * + * @param error The error code + * @return The error description + */ +#if defined(__GNUC__) +__attribute__((__const__)) +#endif +const char *liblss16_encode_strerror(enum liblss16_encode_error error); + + +/** + * Optimise and image + * + * @param header The image metadata + * @param pixel Buffer with pixels; the pixels are to encoded with the + * colour index of each pixel. Pixels are encoded primarily + * from to the top down and secondarily from left to right. + * + * Both `pixels` and `header->colour_map` may be rewritten + * (to an equivalent image with at least as good compression with LSS16) + */ +void liblss16_optimise(struct liblss16_header *header, uint8_t *pixels); + + #endif |