lv_image_decoder.h

Typedefs

typedef _lv_image_src_t lv_image_src_t

typedef struct _lv_image_decoder_dsc_t lv_image_decoder_dsc_t

typedef struct _lv_image_decoder_args_t lv_image_decoder_args_t

Image decoder args. It determines how to decoder an image, e.g. whether to premultiply the alpha or not. It should be passed to lv_img_decoder_open() function. If NULL is provided, default args are used.

Default args: all field are zero or false.

typedef lv_result_t (*lv_image_decoder_info_f_t)(lv_image_decoder_t *decoder, const void *src, lv_image_header_t *header)

Get info from an image and store in the header

Param src:: the image source. Can be a pointer to a C array or a file name (Use lv_image_src_get_type to determine the type)
Param header:: store the info here
Return:: LV_RESULT_OK: info written correctly; LV_RESULT_INVALID: failed

typedef lv_result_t (*lv_image_decoder_open_f_t)(lv_image_decoder_t *decoder, lv_image_decoder_dsc_t *dsc)

Open an image for decoding. Prepare it as it is required to read it later

Param decoder:: pointer to the decoder the function associated with
Param dsc:: pointer to decoder descriptor. src, color are already initialized in it.

typedef lv_result_t (*lv_image_decoder_get_area_cb_t)(lv_image_decoder_t *decoder, lv_image_decoder_dsc_t *dsc, const lv_area_t *full_area, lv_area_t *decoded_area)

Decode len pixels starting from the given x, y coordinates and store them in buf. Required only if the "open" function can't return with the whole decoded pixel array.

Param decoder:: pointer to the decoder the function associated with
Param dsc:: pointer to decoder descriptor
Param x:: start x coordinate
Param y:: start y coordinate
Param len:: number of pixels to decode
Param buf:: a buffer to store the decoded pixels
Return:: LV_RESULT_OK: ok; LV_RESULT_INVALID: failed

typedef void (*lv_image_decoder_close_f_t)(lv_image_decoder_t *decoder, lv_image_decoder_dsc_t *dsc)

Close the pending decoding. Free resources etc.

Param decoder:: pointer to the decoder the function associated with
Param dsc:: pointer to decoder descriptor

typedef struct _lv_image_decoder_cache_data_t lv_image_cache_data_t

typedef struct _lv_image_decoder_header_cache_data_t lv_image_header_cache_data_t

Enums

enum _lv_image_src_t

Source of image.

Values:

enumerator LV_IMAGE_SRC_VARIABLE

enumerator LV_IMAGE_SRC_FILE: Binary/C variable

enumerator LV_IMAGE_SRC_SYMBOL: File in filesystem

enumerator LV_IMAGE_SRC_UNKNOWN: Symbol (lv_symbol_def.h)

Functions

void _lv_image_decoder_init(void): Initialize the image decoder module

void _lv_image_decoder_deinit(void): Deinitialize the image decoder module

lv_result_t lv_image_decoder_get_info(const void *src, lv_image_header_t *header)

Get information about an image. Try the created image decoder one by one. Once one is able to get info that info will be used.

Parameters:

src -- the image source. Can be 1) File name: E.g. "S:folder/img1.png" (The drivers needs to registered via lv_fs_drv_register()) 2) Variable: Pointer to an lv_image_dsc_t variable 3) Symbol: E.g. LV_SYMBOL_OK
header -- the image info will be stored here

Returns:

LV_RESULT_OK: success; LV_RESULT_INVALID: wasn't able to get info about the image

lv_result_t lv_image_decoder_open(lv_image_decoder_dsc_t *dsc, const void *src, const lv_image_decoder_args_t *args)

Open an image. Try the created image decoders one by one. Once one is able to open the image that decoder is saved in dsc

Parameters:

dsc -- describes a decoding session. Simply a pointer to an lv_image_decoder_dsc_t variable.
src -- the image source. Can be 1) File name: E.g. "S:folder/img1.png" (The drivers needs to registered via lv_fs_drv_register())) 2) Variable: Pointer to an lv_image_dsc_t variable 3) Symbol: E.g. LV_SYMBOL_OK
color -- The color of the image with LV_COLOR_FORMAT_ALPHA_...
args -- args about how the image should be opened.

Returns:

LV_RESULT_OK: opened the image. dsc->decoded and dsc->header are set. LV_RESULT_INVALID: none of the registered image decoders were able to open the image.

lv_result_t lv_image_decoder_get_area(lv_image_decoder_dsc_t *dsc, const lv_area_t *full_area, lv_area_t *decoded_area)

Decode an area of the opened image

Parameters:

dsc -- image decoder descriptor
full_area -- start X coordinate (from left)
decoded_area -- start Y coordinate (from top)

Returns:

LV_RESULT_OK: success; LV_RESULT_INVALID: an error occurred

void lv_image_decoder_close(lv_image_decoder_dsc_t *dsc)

Close a decoding session

Parameters:: dsc -- pointer to lv_image_decoder_dsc_t used in lv_image_decoder_open

lv_image_decoder_t *lv_image_decoder_create(void)

Create a new image decoder

Returns:: pointer to the new image decoder

void lv_image_decoder_delete(lv_image_decoder_t *decoder)

Delete an image decoder

Parameters:: decoder -- pointer to an image decoder

lv_image_decoder_t *lv_image_decoder_get_next(lv_image_decoder_t *decoder)

Get the next image decoder in the linked list of image decoders

Parameters:: decoder -- pointer to an image decoder or NULL to get the first one
Returns:: the next image decoder or NULL if no more image decoder exists

void lv_image_decoder_set_info_cb(lv_image_decoder_t *decoder, lv_image_decoder_info_f_t info_cb)

Set a callback to get information about the image

Parameters:

decoder -- pointer to an image decoder
info_cb -- a function to collect info about an image (fill an lv_image_header_t struct)

void lv_image_decoder_set_open_cb(lv_image_decoder_t *decoder, lv_image_decoder_open_f_t open_cb)

Set a callback to open an image

Parameters:

decoder -- pointer to an image decoder
open_cb -- a function to open an image

void lv_image_decoder_set_get_area_cb(lv_image_decoder_t *decoder, lv_image_decoder_get_area_cb_t read_line_cb)

Set a callback to a decoded line of an image

Parameters:

decoder -- pointer to an image decoder
read_line_cb -- a function to read a line of an image

void lv_image_decoder_set_close_cb(lv_image_decoder_t *decoder, lv_image_decoder_close_f_t close_cb)

Set a callback to close a decoding session. E.g. close files and free other resources.

Parameters:

decoder -- pointer to an image decoder
close_cb -- a function to close a decoding session

void lv_image_decoder_set_cache_free_cb(lv_image_decoder_t *decoder, lv_cache_free_cb_t cache_free_cb)

Set a custom method to free cache data. Normally this is not needed. If the custom decoder allocates additional memory other than dsc->decoded draw buffer, then you need to register your own method to free it. By default the cache entry is free'ed in image_decoder_cache_free_cb.

Parameters:

decoder -- pointer to the image decoder
cache_free_cb -- the custom callback to free cache data. Refer to image_decoder_cache_free_cb.

lv_draw_buf_t *lv_image_decoder_post_process(lv_image_decoder_dsc_t *dsc, lv_draw_buf_t *decoded)

Check the decoded image, make any modification if decoder args requires.

Note

A new draw buf will be allocated if provided decoded is not modifiable or stride mismatch etc.

Parameters:

dsc -- pointer to a decoder descriptor
decoded -- pointer to a decoded image to post process to meet dsc->args requirement.

Returns:

post processed draw buffer, when it differs with decoded, it's newly allocated.

struct _lv_image_decoder_args_t

#include <lv_image_decoder.h>

Image decoder args. It determines how to decoder an image, e.g. whether to premultiply the alpha or not. It should be passed to lv_img_decoder_open() function. If NULL is provided, default args are used.

Default args: all field are zero or false.

Public Members

bool stride_align

bool premultiply

bool no_cache

bool use_indexed

struct _lv_image_decoder_t

Public Members

lv_image_decoder_info_f_t info_cb

lv_image_decoder_open_f_t open_cb

lv_image_decoder_get_area_cb_t get_area_cb

lv_image_decoder_close_f_t close_cb

lv_cache_free_cb_t cache_free_cb

void *user_data

struct _lv_image_decoder_cache_data_t

Public Members

lv_cache_slot_size_t slot

const void *src

lv_image_src_t src_type

const lv_draw_buf_t *decoded

const lv_image_decoder_t *decoder

void *user_data

struct _lv_image_decoder_header_cache_data_t

Public Members

const void *src

lv_image_src_t src_type

lv_image_header_t header

lv_image_decoder_t *decoder

struct _lv_image_decoder_dsc_t

#include <lv_image_decoder.h>

Describe an image decoding session. Stores data about the decoding

Public Members

lv_image_decoder_t *decoder: The decoder which was able to open the image source

lv_image_decoder_args_t args

const void *src: The image source. A file path like "S:my_img.png" or pointer to an lv_image_dsc_t variable

lv_image_src_t src_type: Type of the source: file or variable. Can be set in open function if required

lv_image_header_t header: Info about the opened image: color format, size, etc. MUST be set in open function

const lv_draw_buf_t *decoded: Pointer to a draw buffer where the image's data (pixels) are stored in a decoded, plain format. MUST be set in open or get_area_cbfunction

const lv_color32_t *palette

uint32_t palette_size

uint32_t time_to_open: How much time did it take to open the image. [ms] If not set lv_image_cache will measure and set the time to open

const char *error_msg: A text to display instead of the image when the image can't be opened. Can be set in open function or set NULL.

lv_cache_t *cache

lv_cache_entry_t *cache_entry: Point to cache entry information

void *user_data: Store any custom data here is required