libnsbmp.c File Reference

#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <libnsbmp.h>
#include "utils/log.h"

Include dependency graph for libnsbmp.c:

Macros
#define	UNUSED(x)   ((x)=(x))
#define	BMP_FILE_HEADER_SIZE   14
#define	ICO_FILE_HEADER_SIZE   6
#define	ICO_DIR_ENTRY_SIZE   16
#define	BITMAPCOREHEADER   12

Functions
bmp_result	bmp_create (bmp_image *bmp, bmp_bitmap_callback_vt *bitmap_callbacks)
bmp_result	ico_collection_create (ico_collection *ico, bmp_bitmap_callback_vt *bitmap_callbacks)
bmp_result	bmp_analyse (bmp_image *bmp, size_t size, uint8_t *data)
bmp_result	ico_analyse (ico_collection *ico, size_t size, uint8_t *data)
bmp_result	bmp_decode (bmp_image *bmp)
bmp_result	bmp_decode_trans (bmp_image *bmp, uint32_t colour)
bmp_image *	ico_find (ico_collection *ico, uint16_t width, uint16_t height)
void	bmp_finalise (bmp_image *bmp)
void	ico_finalise (ico_collection *ico)

Detailed Description

BMP decoding implementation

This library decode windows bitmaps and icons from their disc images.

The image format is described in several documents: https://msdn.microsoft.com/en-us/library/dd183391(v=vs.85).aspx http://www.fileformat.info/format/bmp/egff.htm https://en.wikipedia.org/wiki/BMP_file_format

Despite the format being clearly defined many bitmaps found on the web are not compliant and this implementation attempts to cope with as many issues as possible rather than simply failing.

Macro Definition Documentation

BITMAPCOREHEADER

#define BITMAPCOREHEADER   12

BMP_FILE_HEADER_SIZE

#define BMP_FILE_HEADER_SIZE   14

ICO_DIR_ENTRY_SIZE

#define ICO_DIR_ENTRY_SIZE   16

ICO_FILE_HEADER_SIZE

#define ICO_FILE_HEADER_SIZE   6

UNUSED

#define UNUSED

(

x

)

((x)=(x))

Function Documentation

bmp_analyse()

bmp_result bmp_analyse	(	bmp_image *	bmp,
		size_t	size,
		uint8_t *	data
	)

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.

Parameters

bmp	the BMP image to analyse.
size	The size of data in cdata.
data	The bitmap source data.

Returns

BMP_OK on success or error code on faliure.

bmp_create()

bmp_result bmp_create	(	bmp_image *	bmp,
		bmp_bitmap_callback_vt *	callbacks
	)

Initialises bitmap ready for analysing the bitmap.

Parameters

bmp	The Bitmap to initialise
callbacks	The callbacks the library will call on operations.

Returns

BMP_OK on success or appropriate error code.

bmp_decode()

bmp_result bmp_decode

(

bmp_image *

bmp

)

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.

Parameters

bmp	the BMP image to decode

Returns

BMP_OK on success

bmp_decode_trans()

bmp_result bmp_decode_trans	(	bmp_image *	bmp,
		uint32_t	transparent_colour
	)

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.

Parameters

bmp	the BMP image to decode
colour	the colour to use as "transparent"

Returns

BMP_OK on success

bmp_finalise()

void bmp_finalise

(

bmp_image *

bmp

)

Finalise a BMP prior to destruction.

Parameters

bmp	the BMP image to finalise.

ico_analyse()

bmp_result ico_analyse	(	ico_collection *	ico,
		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().

Parameters

ico	the ICO image to analyse
size	The size of data in cdata.
data	The bitmap source data.

Returns

BMP_OK on success

ico_collection_create()

bmp_result ico_collection_create	(	ico_collection *	ico,
		bmp_bitmap_callback_vt *	callbacks
	)

Initialises icon ready for analysing the icon

Parameters

bmp	The Bitmap to initialise
callbacks	The callbacks the library will call on operations.

Returns

BMP_OK on success or appropriate error code.

ico_finalise()

void ico_finalise

(

ico_collection *

ico

)

Finalise an ICO prior to destruction.

Parameters

ico	the ICO image to finalise,

ico_find()

bmp_image * ico_find	(	ico_collection *	ico,
		uint16_t	width,
		uint16_t	height
	)

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.

Parameters

ico	the ICO collection to examine
width	the preferred width (0 to use ICO header width)
height	the preferred height (0 to use ICO header height)