Direct sd card image reading support for lvgl

[youkorr]

Feature Request: Direct SD Card Image Reading Support for LVGL

Summary

Add support for direct image reading from SD card in the image section to work seamlessly with LVGL on ESP32-S3 and ESP32-P4 platforms.

Description

Currently, images in ESPHome are stored in the ESP32’s flash memory, which quickly becomes a limitation when working with:

• Background wallpapers for LVGL displays
• Radio station cover art
• Dynamic image content
• Large image libraries

Proposed Feature

Enable the image component to read images directly from an SD card without consuming flash memory space on the ESP32.

Target Platforms

• ESP32-S3
• ESP32-P4

Use Cases

1. Dynamic wallpapers: Store multiple background images on SD card and switch between them
2. Radio station covers: Display album art/station logos loaded from SD card
3. Image galleries: Browse through images stored externally
4. Memory optimization: Keep flash memory available for code and essential data

Technical Requirements

• Integration with existing LVGL image handling
• Support for common image formats (PNG, JPEG, BMP)
• Efficient memory management (load on demand)
• Optional caching mechanism for frequently accessed images
• Fallback to flash-stored images when SD card is unavailable

Proposed Configuration Example

image:

  defaults:
    byte_order: little_endian
    transparency: alpha_channel
    type: rgb565
  image:
    - file: "/sd/wallpapers/background1.png"
      id: bg_image_1
      resize: 320x240
      
    - file: "/sd/radio_covers/station_logo.jpg"
      id: radio_cover
      resize: 64x64

display:
  - platform: ili9xxx  # or other LVGL-compatible display
    # ... other config
    pages:
      - id: main_page
        widgets:
          - image:
              align: CENTER
              src: bg_image_1

Benefits

• Significantly reduces flash memory usage
• Enables dynamic image content
• Supports larger image libraries
• Maintains compatibility with existing LVGL functionality
• Allows for easier content updates via SD card

Additional Considerations

• Error handling for missing SD card or corrupted files
• Performance optimization for image loading
• Integration with existing file system components
• Documentation and examples for implementation

This feature would greatly enhance the capabilities of LVGL-based projects on ESP32 platforms while addressing the critical limitation of flash memory space for image storage.