ESP LV DECODER

[中文]

Allow the use of images in LVGL. Besides that it also allows the use of a custom format, called Split image, which can be decoded in more optimal way on embedded systems.

Referencing the implementation of SJPG.

Features

  • Supports both standard and custom split image formats, including JPG, PNG, and QOI.

  • Decoding standard image requires RAM equivalent to the full uncompressed image size (recommended for devices with more RAM).

  • Split image is a custom format based on standard image formats, specifically designed for LVGL.

  • File reads are implemented for both file storage and C-arrays.

  • Split images are decoded in segments, so zooming and rotating are not supported.

Usage

The esp_mmap_assets component is required. It automatically packages and converts images to your desired format during compilation.

Converting JPG to SJPG

spiffs_create_partition_assets(
     my_spiffs_partition
     my_folder
     FLASH_IN_PROJECT
     MMAP_FILE_SUPPORT_FORMAT ".jpg"
     MMAP_SUPPORT_SJPG
     MMAP_SPLIT_HEIGHT 16)

Converting PNG to SPNG

spiffs_create_partition_assets(
     my_spiffs_partition
     my_folder
     FLASH_IN_PROJECT
     MMAP_FILE_SUPPORT_FORMAT ".png"
     MMAP_SUPPORT_SPNG
     MMAP_SPLIT_HEIGHT 16)

Converting PNG、JPG to QOI

spiffs_create_partition_assets(
     my_spiffs_partition
     my_folder
     FLASH_IN_PROJECT
     MMAP_FILE_SUPPORT_FORMAT ".jpg,.png"
     MMAP_SUPPORT_QOI)

Converting PNG、JPG to SQOI

spiffs_create_partition_assets(
     my_spiffs_partition
     my_folder
     FLASH_IN_PROJECT
     MMAP_FILE_SUPPORT_FORMAT ".jpg,.png"
     MMAP_SUPPORT_QOI
     MMAP_SUPPORT_SQOI
     MMAP_SPLIT_HEIGHT 16)

Application Examples

Register Decoder

Register the decoder function after LVGL starts.

esp_lv_decoder_handle_t decoder_handle = NULL;
esp_lv_decoder_init(&decoder_handle); //Initialize this after lvgl starts

API Reference

Header File

Functions

esp_err_t esp_lv_decoder_init(esp_lv_decoder_handle_t *ret_handle)

Register the decoder functions in LVGL.

Parameters

ret_handle – Pointer to the handle where the decoder handle will be stored

Returns

  • ESP_OK on success

  • ESP_ERR_* error codes on failure

esp_err_t esp_lv_decoder_deinit(esp_lv_decoder_handle_t handle)

Deinitialize the decoder handle.

Parameters

handle – The handle to be deinitialized

Returns

  • ESP_OK on success

  • ESP_ERR_* error codes on failure

Type Definitions

typedef void *esp_lv_decoder_handle_t

Type of handle for the decoder.

Provide feedback about this document