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/*
* Copyright 2006 Richard Wilson <richard.wilson@netsurf-browser.org>
* Copyright 2008 Sean Fox <dyntryx@gmail.com>
*
* This file is part of NetSurf's libnsbmp, http://www.netsurf-browser.org/
* Licenced under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*/
/**
* \file
* Bitmap file decoding interface.
*/
#ifndef libnsbmp_h_
#define libnsbmp_h_
#include <stdbool.h>
#include <stdint.h>
#include <stddef.h>
/* bmp flags */
#define BMP_NEW 0
/** image is opaque (as opposed to having an alpha mask) */
#define BMP_OPAQUE (1 << 0)
/** memory should be wiped */
#define BMP_CLEAR_MEMORY (1 << 1)
/**
* error return values
*/
typedef enum {
BMP_OK = 0,
BMP_INSUFFICIENT_MEMORY = 1,
BMP_INSUFFICIENT_DATA = 2,
BMP_DATA_ERROR = 3
} bmp_result;
/**
* encoding types
*/
typedef enum {
BMP_ENCODING_RGB = 0,
BMP_ENCODING_RLE8 = 1,
BMP_ENCODING_RLE4 = 2,
BMP_ENCODING_BITFIELDS = 3
} bmp_encoding;
/* API for Bitmap callbacks */
typedef void* (*bmp_bitmap_cb_create)(int width, int height, unsigned int state);
typedef void (*bmp_bitmap_cb_destroy)(void *bitmap);
typedef unsigned char* (*bmp_bitmap_cb_get_buffer)(void *bitmap);
typedef size_t (*bmp_bitmap_cb_get_bpp)(void *bitmap);
/**
* The Bitmap callbacks function table
*/
typedef struct bmp_bitmap_callback_vt_s {
/** Callback to allocate bitmap storage. */
bmp_bitmap_cb_create bitmap_create;
/** Called to free bitmap storage. */
bmp_bitmap_cb_destroy bitmap_destroy;
/** Return a pointer to the pixel data in a bitmap. */
bmp_bitmap_cb_get_buffer bitmap_get_buffer;
} bmp_bitmap_callback_vt;
/**
* bitmap image
*/
typedef struct bmp_image {
/** callbacks for bitmap functions */
bmp_bitmap_callback_vt bitmap_callbacks;
/** pointer to BMP data */
uint8_t *bmp_data;
/** width of BMP (valid after _analyse) */
uint32_t width;
/** heigth of BMP (valid after _analyse) */
uint32_t height;
/** whether the image has been decoded */
bool decoded;
/** decoded image */
void *bitmap;
/* Internal members are listed below */
/** total number of bytes of BMP data available */
uint32_t buffer_size;
/** pixel encoding type */
bmp_encoding encoding;
/** offset of bitmap data */
uint32_t bitmap_offset;
/** bits per pixel */
uint16_t bpp;
/** number of colours */
uint32_t colours;
/** colour table */
uint32_t *colour_table;
/** whether to use bmp's limited transparency */
bool limited_trans;
/** colour to display for "transparent" pixels when using limited
* transparency
*/
uint32_t trans_colour;
/** scanlines are top to bottom */
bool reversed;
/** image is part of an ICO, mask follows */
bool ico;
/** true if the bitmap does not contain an alpha channel */
bool opaque;
/** four bitwise mask */
uint32_t mask[4];
/** four bitwise shifts */
int32_t shift[4];
/** colour representing "transparency" in the bitmap */
uint32_t transparent_index;
} bmp_image;
typedef struct ico_image {
bmp_image bmp;
struct ico_image *next;
} ico_image;
/**
* icon image collection
*/
typedef struct ico_collection {
/** callbacks for bitmap functions */
bmp_bitmap_callback_vt bitmap_callbacks;
/** width of largest BMP */
uint16_t width;
/** heigth of largest BMP */
uint16_t height;
/* Internal members are listed below */
/** pointer to ICO data */
uint8_t *ico_data;
/** total number of bytes of ICO data available */
uint32_t buffer_size;
/** root of linked list of images */
ico_image *first;
} ico_collection;
/**
* Initialises bitmap ready for analysing the bitmap.
*
* \param bmp The Bitmap to initialise
* \param callbacks The callbacks the library will call on operations.
* \return BMP_OK on success or appropriate error code.
*/
bmp_result bmp_create(bmp_image *bmp, bmp_bitmap_callback_vt *callbacks);
/**
* Initialises icon ready for analysing the icon
*
* \param bmp The Bitmap to initialise
* \param callbacks The callbacks the library will call on operations.
* \return BMP_OK on success or appropriate error code.
*/
bmp_result ico_collection_create(ico_collection *ico,
bmp_bitmap_callback_vt *callbacks);
/**
* Analyse a BMP prior to decoding.
*
* This will scan the data provided and perform checks to ensure the data is a
* valid BMP and prepare the bitmap image structure ready for decode.
*
* This function must be called and resturn BMP_OK before bmp_decode() as it
* prepares the bmp internal state for the decode process.
*
* \param bmp the BMP image to analyse.
* \param size The size of data in cdata.
* \param data The bitmap source data.
* \return BMP_OK on success or error code on faliure.
*/
bmp_result bmp_analyse(bmp_image *bmp, size_t size, uint8_t *data);
/**
* Analyse an ICO prior to decoding.
*
* This function will scan the data provided and perform checks to ensure the
* data is a valid ICO.
*
* This function must be called before ico_find().
*
* \param ico the ICO image to analyse
* \param size The size of data in cdata.
* \param data The bitmap source data.
* \return BMP_OK on success
*/
bmp_result ico_analyse(ico_collection *ico, size_t size, uint8_t *data);
/**
* Decode a BMP
*
* This function decodes the BMP data such that bmp->bitmap is a valid
* image. The state of bmp->decoded is set to TRUE on exit such that it
* can easily be identified which BMPs are in a fully decoded state.
*
* \param bmp the BMP image to decode
* \return BMP_OK on success
*/
bmp_result bmp_decode(bmp_image *bmp);
/**
* Decode a BMP using "limited transparency"
*
* Bitmaps do not have native transparency support. However, there is a
* "trick" that is used in some instances in which the first pixel of the
* bitmap becomes the "transparency index". The decoding application can
* replace this index with whatever background colour it chooses to
* create the illusion of transparency.
*
* When to use transparency is at the discretion of the decoding
* application.
*
* \param bmp the BMP image to decode
* \param colour the colour to use as "transparent"
* \return BMP_OK on success
*/
bmp_result bmp_decode_trans(bmp_image *bmp, uint32_t transparent_colour);
/**
* Finds the closest BMP within an ICO collection
*
* This function finds the BMP with dimensions as close to a specified set
* as possible from the images in the collection.
*
* \param ico the ICO collection to examine
* \param width the preferred width (0 to use ICO header width)
* \param height the preferred height (0 to use ICO header height)
*/
bmp_image *ico_find(ico_collection *ico, uint16_t width, uint16_t height);
/**
* Finalise a BMP prior to destruction.
*
* \param bmp the BMP image to finalise.
*/
void bmp_finalise(bmp_image *bmp);
/**
* Finalise an ICO prior to destruction.
*
* \param ico the ICO image to finalise,
*/
void ico_finalise(ico_collection *ico);
#endif
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