RREFont

Fast RRE Font rendering library

TL;DR: RRE fonts are rendered using optimized set of rectangles instead of pixels like in typical bitmap approach.

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Configuration

In RREFont.h use following flags:

// ---------  CONFIG ----------
// adds 400 bytes
#define CONVERT_PL_CHARS    1
// adds 720 bytes
#define ENABLE_NOSORT       0
// enable only unused types to save memory (up to 4-5 kbytes)
#define ENABLE_RRE_16B      1
#define ENABLE_RRE_24B      1
#define ENABLE_RRE_32B      1
#define ENABLE_RRE_V16B     1
#define ENABLE_RRE_V16B_BG  1  // support for non-flickering background clear
#define ENABLE_RRE_H16B     1
#define ENABLE_RRE_H16B_BG  1
#define ENABLE_RRE_V24B     1
#define ENABLE_RRE_V24B_BG  1
#define ENABLE_RRE_H24B     1
#define ENABLE_RRE_H24B_BG  0
#define ENABLE_RRE_P8B      0
#define ENABLE_RRE_P16B     1
// ----------------------------

If you are low with memory consider disabling all BG modes (support for non-flickering background) and other unused modes/types

To avoid flickering draw chars to the buffer in RAM then render it to LCD using lcd.drawImage()

Main advantages:

very fast rendering even on slow MCUs
usually such fonts save a lot of memory especially for large fonts (for example 97x104 Times font takes only about 18k of flash instead of 120k bitmap font)
RRE fonts can be easily scaled in both directions
this library can be used also for rendering bitmaps (which in RRE format use much less memory)
special vertical or horizontal lines mode supported for special applications
separate pixels mode supported too
the most efficient for large color LCDs
there are over 40 various size fonts included
antialiased fonts are possible https://github.com/cbm80amiga/ST7735_antialiased_rre_fonts

Requirements:

any Arduino graphics library supporting "fillRect()" function

Tested with:

own ST7920 gfx library
SSD1306 OLED + Adafruit GFX Library
own ST7735/ST7789/ILI9341 SPI + Adafruit GFX Library
own ILI9327, ST7781 TFT libs

Most used methods

void init(void (*rectFun)(int x, int y, int w, int h, int c), int swd, int sht);
   Inits the library with rectFun callback and screen dimensions
void setFillRectFun(void (*fun)(int x, int y, int w, int h, int c))
   Changes default fill rect callback
void setFont(RRE_Font *f)
   Sets current font
void setCR(uint8_t _cr)
   Switches 'carriage return' mode (text wrapping)
void setFg(int _fg)
void setBg(int _bg)
void setColor(int c)
void setColor(int c, int _bg)
   setFg/setBg are obsolete, use setColor to change background/foreground colors
   If background and foreground are the same only foreground color is used to render (transparent background)
void setBold(uint8_t _bold)
  Sets bold mode
void setSpacing(uint8_t sp)
void setSpacingY(uint8_t sp)
  Sets distances between characters and lines
void setScale(uint8_t _sx, uint8_t _sy)
void setScale(uint8_t s)
  Sets scale in X/Y axes
void setFontMinWd(uint8_t wd)
void setCharMinWd(uint8_t wd)
  Sets min char width for entire font to ensure fixed width rendering
void setDigitMinWd(uint8_t wd)
  Sets min char width to ensure fixed width rendering for digits, + and space
  Callback for isNumber() can be changed by setIsNumberFun()

int getWidth()
int getHeight()
  Returns fong global width/height
int charWidth(uint8_t c, int *_xmin=0)
  Returns the width for the given character
int strWidth(char *str)
  Returns the width for entire string
int drawChar(int x, int y, unsigned char c)
  Draws single character
int printStr(int xpos, int ypos, char *str)
  Draws char* string

Support

If you find it useful and want to buy me a coffee or a beer:

https://www.paypal.me/cbm80amiga

inapp123 / RREFont_esp_idf