An Arduino IDE compatible graphics and fonts library for ESP8266 and ESP32 processors with a driver for ILI9341, ILI9163, ST7735 and S6D02A1 based TFT displays that support SPI.
The library also supports TFT displays designed for the Raspberry Pi that are based on a ILI9486 driver chip with a 480 x 320 pixel screen. This display must be of the Waveshare design and use a 16 bit serial interface based on the 74HC04, 74HC4040 and 2 x 74HC4094 logic chips. A modification to these displays is possible (see mod image in Tools folder) to make many graphics functions much faster (e.g. 23ms to clear the screen, 1.2ms to draw a 72 pixel high numeral).
A new "Sprite" class has been added, this enables flicker free updates of complex graphics. Direct writes to the TFT with graphics functions are still available, so existing sketches do not need to be changed.
A Sprite is notionally an invisible graphics screen that is kept in the processors RAM. Graphics can be drawn into the Sprite just as they can be drawn directly to the screen. Once the Sprite is completed it can be plotted onto the screen in any position. If there is sufficient RAM then the Sprite can be the same size as the screen and used as a frame buffer. Sprites by default use 16 bit colours, the bit depth can be set to 8 bits to reduce the RAM needed. On an ESP8266 the largest 16 bit colour Sprite that can be created is about 160x128 pixels, this consumes 40Kbytes of RAM. On an ESP32 the workspace RAM is more limited than the datsheet implies so a 16 bit colour Sprite is limited to about 200x200 pixels (~80Kbytes) and an 8 bit sprite to 320x240 pixels (~76kbytes).
One or more sprites can be created, a sprite can be any width and height, limited only by available RAM. The RAM needed for a 16 bit colour depth Sprite is (2 x width x height) bytes, for a Sprite with 8 bit colour depth the RAM needed is (width x height) bytes. Sprites can be created and deleted dynamically as needed in the sketch, this means RAM can be freed up after the sprite has been plotted on the screen, more RAM intensive WiFi based code can then be run and normal graphics operations still work.
Drawing graphics into a sprite is very fast, for those familiar with the Adafruit "graphicstest" example, this whole test completes in less than 27ms in a 160x128 sprite. Examples of sprite use can be found in the "examples/Sprite" folder.
The XPT2046 touch screen controller is supported. The SPI bus for the touch controller is shared with the TFT and only an additional chip select line is needed.
The Button class from Adafruit_GFX is incorporated, with the enhancement that the button labels can be in any font.
The library supports SPI overlap on the ESP8266 so the TFT screen can share MOSI, MISO and SCLK pins with the program FLASH.
The library contains proportional fonts, different sizes can be enabled/disabled at compile time to optimise the use of FLASH memory. The library has been tested with the NodeMCU (ESP8266 based) and an ESP32 demo board.
The library is based on the Adafruit GFX and Adafruit driver libraries and the aim is to retain compatibility. Significant additions have been made to the library to boost the speed for ESP8266/ESP32 processors (it is typically 3 to 10 times faster) and to add new features. The new graphics functions include different size proportional fonts and formatting features. There are a significant number of example sketches to demonstrate the different features.
Configuration of the library font selections, pins used to interface with the TFT and other features is made by editting the User_Setup.h file in the library folder. Fonts and features can easily be disabled by commenting out lines.