Documentation
Tinyfont

Tinyfont

tinygo.org/x/tinyfont is a lightweight font rendering library designed for microcontrollers. It works with any display that implements the drivers.Displayer interface — OLEDs, TFT screens, e-ink panels — and draws text one pixel at a time, making it ideal for resource-constrained environments where a full font engine would be too large.

Quick start

import (
    "image/color"
    "tinygo.org/x/tinyfont"
)

// disp is any drivers.Displayer (e.g. an SSD1306 OLED or ILI9341 TFT)
tinyfont.WriteLine(disp, &tinyfont.TomThumb, 2, 14, "Hello!", color.RGBA{R: 0xff, A: 0xff})

WriteLine signature:

func WriteLine(display drivers.Displayer, font Fonter, x, y int16, str string, c color.RGBA)
ParameterDescription
displayTarget display — anything with SetPixel + Size
fontA Fonter value — pointer to one of the font variables
x, yTop-left origin of the text baseline (pixels)
strThe string to render (ASCII; full Unicode depends on font)
cForeground color as color.RGBA

Built-in fonts

The root package ships four bitmap fonts that range from tiny to small:

VariableSizeBest for
tinyfont.Tiny3x3a2pt7b3×3 pxStatus indicators, tiny labels
tinyfont.Picopixel~5 pxDense data on small OLEDs
tinyfont.TomThumb~6 pxCompact, very readable at small sizes
tinyfont.Org01~6 pxClean monospace look

Sub-packages (freemono, freesans, freeserif, notosans, proggy, gophers) add larger proportional and monospace faces at the cost of binary size.

The drivers.Displayer interface

type Displayer interface {
    // SetPixel draws a single pixel at (x, y) with color c.
    SetPixel(x, y int16, c color.RGBA)

    // Size returns the display dimensions in pixels.
    Size() (x, y int16)

    // Display flushes buffered data to the hardware (no-op for direct-write displays).
    Display() error
}

Any struct that satisfies these three methods can be passed to tinyfont.WriteLine. The TinyGo drivers package provides ready-made implementations for most common displays.

Multi-line text

For displays with limited height, you can call WriteLine multiple times advancing y by the font’s line height:

lineH := int16(10)
y := lineH
for _, line := range strings.Split(text, "\n") {
    tinyfont.WriteLine(disp, &tinyfont.TomThumb, 2, y, line, white)
    y += lineH
}

Font tester

Try out the built-in fonts directly in the browser. The widget below runs the same rendering code you would use on a real microcontroller, compiled with TinyGo to WebAssembly.

Loading WASM…

Select a font, adjust colors, choose a display size, and type your text to preview exactly how it will look on the target hardware.

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