LovyanGFX

By default, LovyanGFX handles SPI bus acquisition and release automatically for every drawing function. For high-performance applications, you can manually manage the SPI bus to reduce overhead.

• lcd.startWrite(): Manually acquires the SPI bus. It uses a counter; multiple calls increment the counter, and only the first call actually acquires the bus.
• lcd.endWrite(): Releases the SPI bus (decrements the counter). Only the last call actually releases the bus.
• lcd.endTransaction() / lcd.beginTransaction(): Use these to force a bus release/acquisition regardless of the startWrite counter. This is useful if you need to switch to another SPI device (like an SD card) mid-operation.

Warning: Functions starting with write (e.g., writePixel, writeFastVLine, writeFillRect) do not check the SPI bus state and require an explicit startWrite() call before use.

// High-speed drawing block
lcd.startWrite();
lcd.drawLine(38, 0, 0, 38, 0xFFFF00U);
lcd.drawLine(39, 1, 1, 39, 0xFF00FFU);
lcd.endWrite();

// Using high-speed 'write' functions
lcd.startWrite();
for (uint32_t x = 0; x < 128; ++x) {
  for (uint32_t y = 0; y < 128; ++y) {
    lcd.writePixel(x, y, lcd.color888(x*2, x + y, y*2));
  }
}
lcd.endWrite();

A Sprite is an off-screen buffer that allows you to draw complex graphics and then push them to the display all at once. This prevents flickering and enables fast rotation/scaling.

Workflow:

1. Create a LGFX_Sprite instance, passing the display instance as an argument.
2. Set the color depth using sprite.setColorDepth(n) (e.g., 8, 16, or 24).
3. Allocate memory with sprite.createSprite(width, height).
4. Draw to the sprite using standard drawing functions.
5. Push the sprite to the display using sprite.pushSprite(x, y) or sprite.pushRotateZoom(...).
6. Free memory with sprite.deleteSprite() when finished.

Palette Mode (for 1, 2, 4, or 8-bit depth): In palette mode, drawing functions use a palette index instead of a color. You can define colors for these indices using sprite.setPaletteColor(index, color).

Rotation and Zoom: sprite.pushRotateZoom(x, y, angle, scale_x, scale_y, pivot_x, pivot_y) allows you to render the sprite with rotation and scaling. Use sprite.setPivot(x, y) to define the center of rotation.

To use LovyanGFX with a supported board, you can either define the specific board macro before including the header or use LGFX_AUTODETECT to automatically identify the board at runtime.

Using Automatic Detection: Define LGFX_AUTODETECT before including LovyanGFX.hpp. Note that some boards like D-duino-32 XS, WT32-SC01, and PyBadge do not support panel ID reading and are excluded from autodetect.

Using Specific Board Definitions: If autodetect is not used, define the appropriate macro for your hardware (e.g., LGFX_M5STACK, LGFX_M5STICK_C, LGFX_WIO_TERMINAL, etc.).

Note for non-ArduinoIDE environments: If you are not using the Arduino IDE or your board is not in the Board Manager, you must define the LGFX_... macro before the #include <LovyanGFX.hpp> line.

// Define the board before including the header
#define LGFX_AUTODETECT

#include <LovyanGFX.hpp>
#include <LGFX_AUTODETECT.hpp>

static LGFX lcd;
static LGFX_Sprite sprite(&lcd);

To convert BDF files into C source files compatible with the u8g2 format used in LovyanGFX, use bdfconv.exe. This process utilizes a mapping file (specifically a modified ja.map based on japanese3.map) to ensure correct character encoding.

Command Flags:

• -v: Verbose mode.
• -b 0: Bit depth/format setting.
• -f 1: Font format setting.
• -M "[map_file]": Specifies the character map file (e.g., japanese3.map).
• -o [output_file].c: Specifies the output C file path.
• -n [font_name]: Specifies the internal font name used in the C file.

After conversion, the resulting .c files are typically collected into a single lgfx_font_japan.c file, often requiring a regex replacement of /U8G2_FONT_SECTION\(".*"\) // to match the project's expected format.

bdfconv.exe -v -b 0 -f 1 -M "japanese3.map" ..\bdf\lgfx_font_japan_mincho_16.bdf -o ..\output\lgfx_font_japan_mincho_16.c -n lgfx_font_japan_mincho_16