Just received the following notification from Digi-Key:

You have purchased the following part number from Digi-Key within the last two years. The manufacturer has announced an update to the part status.
Part Affected
Manufacturer M5STACK TECHNOLOGY CO., LTD
Description M5PAPER ESP32 DEV KIT 4.7"E-INK
Manufacturer Part Number K049
Digi-Key Part Number 2221-K049-ND
Status Obsolete
Substitutes Please click here

Digging around leads to: https://media.digikey.com/pdf/PCNs/M5Stack/PCN20210513-01.pdf

Which contains: "The display driver chipset for K049 cannot be purchased and supplier from our vendor any more. We will look for new display driver as the alternative material. This version will stop for sale. "

I have written a reader for simpler formats (plain text with a bit of markdowny style syntax), I didn't find the TFT_eSPI interface to be limiting, except in not being able to handle multiple TTF fonts, which I was able to solve.

I think you'd need to have a specific problem that the provided library didn't handle to take the hassle of trying to get something else working.

@felmue I've updated the code, it should now compile with no warnings in PlatformIO.

@felmue I'll try to get PlatformIO set up and take a look, thanks,

@bwubs Just one, which you have to specify when compiling the app.

Source available here: https://github.com/murraypaul/M5Sudoku

M5Sudoku

Sudoku application for M5Paper

Can generate uniquely solveable Sudoku puzzles, targetting a given number of clues, to act as a difficulty setting.

At any point, can validate that the puzzle is still solvable.

Can mark squares as either a known value, or a set of possible values.

Can save and reload current state to EEPROM.

Will automatically shutdown and save state after 5 minutes of inactivity.

Notes:

• Selecting a square in the large grid will display it in the small grid on the right
• The selected square is highlighted in the large grid
• You can use the small grid to either set a single known value for the square, or select multiple possible values
• It may not be possible to generate a uniquely solveable puzzle of the given numbers of clues in the time requested
• In this situation, the puzzle with the lowest number of clues that still gives a unqiue solution will be returned
• The fewer target clues you ask for, the longer it will take to generate the puzzle
• The 'Validate' button will confirm that the puzzle is still uniquely solveable
• The 'Clue' button will fill in one randon unsolved square
• Over time the screen may get a bit muddy, due to the fast refresh option used on the EPD screen
• The 'Validate' button will also do a full screen slow refresh, which will clean up the display

The most likely issue is that the filename you pass doesn't start with '/', which is required by the SD library.

To view the logging output, assuming you are using the Arduino UI, first do Tools->Core Debug Level->Set to Debug or Verbose. Then do Tools->Serial Monitor.
You will see debug output from the M5Paper appear in the serial monitor window.

I have a M5Paper, not a Core2, but the APIs look very similar.
You can use something like bin2header (https://github.com/AntumDeluge/bin2header) to convert your jpg file to a C header file and include that in your project. It will start with something like:

static const unsigned char my_file_name_jpg[] = {...

You can then use the memory buffer form of drawJpg:

      void drawJpg(const uint8_t *jpg_data, size_t jpg_len, uint16_t x = 0,
                  uint16_t y = 0, uint16_t maxWidth = 0, uint16_t maxHeight = 0,
                  uint16_t offX = 0, uint16_t offY = 0,
                  jpeg_div_t scale = JPEG_DIV_NONE);

Like this:

drawJpg(my_file_name_jpg,sizeof(my_file_name_jpg),x,y,...)

(As the other poster said, this might not be the best way of doing it, but it is available.)

Application to monitor and control a Spotify client using the M5Paper.
Note: This is not itself a Spotify client, it cannot stream Spotify through the M5Paper.

Three screen layouts available, show below.
Initial Spotify authentication through a built-on webserver, then refresh token saved to EEPROM and should function independently.

Polls Spotify to update data at one of two compile-time configurable rates, depending on whether there is currently an active Spotify device found or not. Shuts down after configurable interval with no active client found if running on battery.

You need to create a (free) developer account and client app with Spotify, and approve access of this application to your Spotify account.

Requested scopes are:

• user-read-private
• user-read-currently-playing
• user-read-recently-played
• user-read-playback-state
• user-modify-playback-state

Code available at https://github.com/murraypaul/M5Spot.
Based on original M5Spot project by Cosmic Mac available at https://github.com/CosmicMac/M5Spot.

Icons by icons8.

My question is, if the behavior is required or an artifact of the integration with the driver?

I think this is required.
When actually transferring data to the screen, this is done 4 pixels at a time.

Shouldn't the library simply forbid creating a canvas that is not a multiple of 4?

Probably, yes.