256 lines
7.4 KiB
C
256 lines
7.4 KiB
C
/*
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* Copyright 2006 Richard Wilson <richard.wilson@netsurf-browser.org>
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* Copyright 2008 Sean Fox <dyntryx@gmail.com>
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*
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* This file is part of NetSurf's libnsbmp, http://www.netsurf-browser.org/
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* Licenced under the MIT License,
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* http://www.opensource.org/licenses/mit-license.php
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*/
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/**
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* \file
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* Bitmap file decoding interface.
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*/
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#ifndef libnsbmp_h_
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#define libnsbmp_h_
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//#include <stdbool.h>
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#include <stdint.h>
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#include <stddef.h>
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/* bmp flags */
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#define BMP_NEW 0
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/** image is opaque (as opposed to having an alpha mask) */
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#define BMP_OPAQUE (1 << 0)
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/** memory should be wiped */
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#define BMP_CLEAR_MEMORY (1 << 1)
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/**
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* error return values
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*/
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typedef enum {
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BMP_OK = 0,
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BMP_INSUFFICIENT_MEMORY = 1,
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BMP_INSUFFICIENT_DATA = 2,
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BMP_DATA_ERROR = 3
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} bmp_result;
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/**
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* encoding types
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*/
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typedef enum {
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BMP_ENCODING_RGB = 0,
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BMP_ENCODING_RLE8 = 1,
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BMP_ENCODING_RLE4 = 2,
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BMP_ENCODING_BITFIELDS = 3
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} bmp_encoding;
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/* API for Bitmap callbacks */
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typedef void* (*bmp_bitmap_cb_create)(int width, int height, unsigned int state);
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typedef void (*bmp_bitmap_cb_destroy)(void *bitmap);
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typedef unsigned char* (*bmp_bitmap_cb_get_buffer)(void *bitmap);
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typedef size_t (*bmp_bitmap_cb_get_bpp)(void *bitmap);
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/**
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* The Bitmap callbacks function table
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*/
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typedef struct bmp_bitmap_callback_vt_s {
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/** Callback to allocate bitmap storage. */
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bmp_bitmap_cb_create bitmap_create;
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/** Called to free bitmap storage. */
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bmp_bitmap_cb_destroy bitmap_destroy;
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/** Return a pointer to the pixel data in a bitmap. */
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bmp_bitmap_cb_get_buffer bitmap_get_buffer;
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/** Find the width of a pixel row in bytes. */
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bmp_bitmap_cb_get_bpp bitmap_get_bpp;
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} bmp_bitmap_callback_vt;
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/**
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* bitmap image
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*/
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typedef struct bmp_image {
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/** callbacks for bitmap functions */
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bmp_bitmap_callback_vt bitmap_callbacks;
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/** pointer to BMP data */
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uint8_t *bmp_data;
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/** width of BMP (valid after _analyse) */
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uint32_t width;
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/** heigth of BMP (valid after _analyse) */
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uint32_t height;
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/** whether the image has been decoded */
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bool decoded;
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/** decoded image */
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void *bitmap;
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/* Internal members are listed below */
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/** total number of bytes of BMP data available */
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uint32_t buffer_size;
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/** pixel encoding type */
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bmp_encoding encoding;
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/** offset of bitmap data */
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uint32_t bitmap_offset;
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/** bits per pixel */
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uint16_t bpp;
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/** x_pels_per_meter */
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int32_t x_pels_per_meter;
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/** y_pels_per_meter */
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int32_t y_pels_per_meter;
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/** 222 */
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/** number of colours */
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uint32_t colours;
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/** colour table */
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uint32_t *colour_table;
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/** whether to use bmp's limited transparency */
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bool limited_trans;
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/** colour to display for "transparent" pixels when using limited
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* transparency
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*/
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uint32_t trans_colour;
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/** scanlines are top to bottom */
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bool reversed;
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/** image is part of an ICO, mask follows */
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bool ico;
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/** true if the bitmap does not contain an alpha channel */
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bool opaque;
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/** four bitwise mask */
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uint32_t mask[4];
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/** four bitwise shifts */
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int32_t shift[4];
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/** colour representing "transparency" in the bitmap */
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uint32_t transparent_index;
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} bmp_image;
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typedef struct ico_image {
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bmp_image bmp;
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struct ico_image *next;
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} ico_image;
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/**
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* icon image collection
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*/
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typedef struct ico_collection {
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/** callbacks for bitmap functions */
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bmp_bitmap_callback_vt bitmap_callbacks;
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/** width of largest BMP */
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uint16_t width;
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/** heigth of largest BMP */
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uint16_t height;
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/* Internal members are listed below */
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/** pointer to ICO data */
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uint8_t *ico_data;
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/** total number of bytes of ICO data available */
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uint32_t buffer_size;
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/** root of linked list of images */
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ico_image *first;
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} ico_collection;
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/**
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* Initialises bitmap ready for analysing the bitmap.
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*
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* \param bmp The Bitmap to initialise
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* \param callbacks The callbacks the library will call on operations.
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* \return BMP_OK on success or appropriate error code.
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*/
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bmp_result bmp_create(bmp_image *bmp, bmp_bitmap_callback_vt *callbacks);
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/**
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* Initialises icon ready for analysing the icon
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*
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* \param bmp The Bitmap to initialise
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* \param callbacks The callbacks the library will call on operations.
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* \return BMP_OK on success or appropriate error code.
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*/
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bmp_result ico_collection_create(ico_collection *ico,
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bmp_bitmap_callback_vt *callbacks);
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/**
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* Analyse a BMP prior to decoding.
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*
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* This will scan the data provided and perform checks to ensure the data is a
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* valid BMP and prepare the bitmap image structure ready for decode.
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*
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* This function must be called and resturn BMP_OK before bmp_decode() as it
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* prepares the bmp internal state for the decode process.
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*
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* \param bmp the BMP image to analyse.
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* \param size The size of data in cdata.
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* \param data The bitmap source data.
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* \return BMP_OK on success or error code on faliure.
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*/
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bmp_result bmp_analyse(bmp_image *bmp, size_t size, uint8_t *data);
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/**
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* Analyse an ICO prior to decoding.
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*
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* This function will scan the data provided and perform checks to ensure the
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* data is a valid ICO.
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*
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* This function must be called before ico_find().
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*
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* \param ico the ICO image to analyse
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* \param size The size of data in cdata.
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* \param data The bitmap source data.
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* \return BMP_OK on success
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*/
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bmp_result ico_analyse(ico_collection *ico, size_t size, uint8_t *data);
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/**
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* Decode a BMP
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*
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* This function decodes the BMP data such that bmp->bitmap is a valid
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* image. The state of bmp->decoded is set to TRUE on exit such that it
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* can easily be identified which BMPs are in a fully decoded state.
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*
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* \param bmp the BMP image to decode
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* \return BMP_OK on success
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*/
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bmp_result bmp_decode(bmp_image *bmp);
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/**
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* Decode a BMP using "limited transparency"
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*
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* Bitmaps do not have native transparency support. However, there is a
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* "trick" that is used in some instances in which the first pixel of the
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* bitmap becomes the "transparency index". The decoding application can
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* replace this index with whatever background colour it chooses to
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* create the illusion of transparency.
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*
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* When to use transparency is at the discretion of the decoding
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* application.
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*
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* \param bmp the BMP image to decode
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* \param colour the colour to use as "transparent"
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* \return BMP_OK on success
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*/
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bmp_result bmp_decode_trans(bmp_image *bmp, uint32_t transparent_colour);
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/**
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* Finds the closest BMP within an ICO collection
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*
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* This function finds the BMP with dimensions as close to a specified set
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* as possible from the images in the collection.
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*
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* \param ico the ICO collection to examine
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* \param width the preferred width (0 to use ICO header width)
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* \param height the preferred height (0 to use ICO header height)
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*/
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bmp_image *ico_find(ico_collection *ico, uint16_t width, uint16_t height);
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/**
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* Finalise a BMP prior to destruction.
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*
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* \param bmp the BMP image to finalise.
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*/
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void bmp_finalise(bmp_image *bmp);
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/**
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* Finalise an ICO prior to destruction.
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*
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* \param ico the ICO image to finalise,
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*/
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void ico_finalise(ico_collection *ico);
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#endif
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