Font scaling on SSD1306 OLED displays

[kresimirhec]

Here is a solution for scaling fonts I came up with....
I originally wrote this elsewhere but a user suggested that I should poste this here

NB: I am using ESP32-WROOM-32, 0.91" OLED 128x32

from machine import SoftI2C, Pin
import time
import ssd1306

OLED_SCL_PIN = 22  # clock
OLED_SDA_PIN = 21  # data
OLED_WIDTH = 128  # pixels
OLED_HEIGHT = 32  # pixels


def oled_text_scaled(oled, text, x, y, scale, character_width=8, character_height=8):
    # temporary buffer for the text
    width = character_width * len(text)
    height = character_height
    temp_buf = bytearray(width * height)
    temp_fb = ssd1306.framebuf.FrameBuffer(temp_buf, width, height, ssd1306.framebuf.MONO_VLSB)

    # write text to the temporary framebuffer
    temp_fb.text(text, 0, 0, 1)

    # scale and write to the display
    for i in range(width):
        for j in range(height):
            pixel = temp_fb.pixel(i, j)
            if pixel:  # If the pixel is set, draw a larger rectangle
                oled.fill_rect(x + i * scale, y + j * scale, scale, scale, 1)


def main():
    i2c = SoftI2C(scl=Pin(OLED_SCL_PIN), sda=Pin(OLED_SDA_PIN))
    oled = ssd1306.SSD1306_I2C(OLED_WIDTH, OLED_HEIGHT, i2c)

    # no scaling
    oled.fill(0)
    oled.text("ABCDEFGHIJKLMNOP", 0, 0)
    oled.text("abcdefghijklmnop", 0, 8)
    oled.text("0123456789012345", 0, 16)
    oled.text("=!\"#$%&/()?-+*:;", 0, 24)
    oled.show()
    time.sleep(3)

    # 2x
    oled.fill(0)
    oled_text_scaled(oled, "ABCDEFGH", 0, 0, 2)
    oled_text_scaled(oled, "abcdefgh", 0, 16, 2)
    oled.show()
    time.sleep(3)

    # 4x
    oled.fill(0)
    oled_text_scaled(oled, "ABCD", 0, 0, 4)
    oled.show()
    time.sleep(3)


if __name__ == "__main__":
    main()

For convenience, one can also extend the imported class:

ssd1306.SSD1306_I2C.text_scaled = oled_text_scaled

...and then use it slightly nicer way:

    ...
    oled.text_scaled("ABCD", 0, 0, 4)
    ...

[jonnor]

Thanks for sharing the code! This will help future travellers interested in a simple way of having fonts at different sizes, without including a large set of different fixed-height fonts.

[scruss]

It's also bringing back memories of how we did font scaling on 8-bit computers by printing text black-on-black at the bottom left of the screen, then scanning and scaling up those "invisible" pixels ...

[IHOXOHI]

Nice!
Very good idea.
So, useful!
I have thought about a solution during so many time, your's is fine.
Thanks.

[davefes]

Thanks for that. Even with no scaling I can now read the display!

[bradcar]

This is cool

also take a look at: https://github.com/peterhinch/micropython-font-to-py
and https://github.com/easytarget/microPyEZfonts

between them you can find different sizes and fonts.

[IHOXOHI]

for doing your own font...[https://github.com/IHOXOHI/Font4x4]

[bradcar]

@IHOXOHI I encourage you to put more into your GitHub readme to explain what your code is doing and what it's unique features are.

[IHOXOHI]

ok, I will, thanks...