Beware that these classes are **not** re-entrant. That means that it is not possible to use them in a multi-thread context without proper mutual exclusion access control.
This project is a working example. You can build it using PlatformIO. It will draw a square and a straight line on the device display.
## Modifications done to the Arduino Inkplate Source code
As you can expect, the ESP-IDF framework is quit different than the Arduino framework. The porting effort of the Inkplate source code done here is not just a transformation to make it runs, but also getting it inline with the available packages available with the ESP-IDF. Many aspects must be transformed in this regard. Here is a list of the changes being done:
### Global changes
- Give the overall source code a transformation to use what is called *modern C++*, alligned with C++17
- All .h files are renamed .hpp
- macro definitions (`#define`) are reduced to a minimum
-`enum class` are used everywhere possible
- source code filenames are all in lowercase
- The module is used only to initialize the ESP-IDF drivers (SPI and FAT filesystem are used). The card can then be accessed through the standard C++/C capabilities. All filenames located on the card must be prefixed with `/sdcard`.
### Image (.hpp, .cpp)
- the `drawXXXXFromWeb(WiFiClient *s, ...)` methods are no longer available.
- the `bool drawXXXXFromSd(SdFile *p, ...)` methods are renamed `bool drawXXXXFromFile(File *p, ...)`.
## ESP-IDF configuration specifics
An InkPlate application requires some functionalities to be properly set up within the ESP-IDF. The following elements have been done for this project and can be used as a reference for other projects:
- **PSRAM memory management**: The PSRAM is an extension to the ESP32 memory that offers 4MB+4MB of additional RAM. The first 4MB is readily available to integrate into the dynamic memory allocation of the ESP-IDF SDK. To do so, some parameters located in the `sdkconfig` file must be set accordingly. This must be done using the menuconfig application that is part of the ESP-IDF. The following command will launch the application (the current folder must be the main folder of EPub-InkPlate):
$ idf.py menuconfig
The application will show a list of configuration aspects. To configure PSRAM:
- **FAT Filesystem Support**: If the application requires the usage of the micro SD card. This card must be formatted on a computer (Linux or Windows) with a FAT 32 partition. The InkPlate6Ctrl class requires this in its current configuration. The following parameters must be adjusted in `sdkconfig`:
- Select `Number of simultaneously open files protected by lock function` > `5`
- Select `Prefer external RAM when allocating FATFS buffer`
- **Flash memory partitioning (optional)**: the file `partitions.csv` contains the table of partitions definition for the 4MB flash memory, required to support the largest applications size in an OTA context. The partitions OTA_0 and OTA_1 have been set to be 1.3MB in size. In the `platformio.ini` file, the line `board_build.partitions=...` is directing the use of these partitions configuration.