Adafruit OLED - how to center text.

Other Hardware Displays
1

Hello. I have 2,42" OLED display with Adafruit library. Its possible to set function like "setCenter" for X,Y coordinates? (One time I set X,Y , then only "setCenter" for X,Y.

For example, now I have 6 different text:
ONE
TWO
THREE
FOUR
FIVE
SIX

some of them have different number of lettetrs, and I need to put different X,Y coordinates (6 times) to have all text in one position, center.

2

Google "Adafruit getTextBounds()"

Write helper functions for Centered text, Right aligned text, ...
e.g. calculate width of string. calculate the correct Cursor position. set Cursor and print the string.

David.

3

"calculate the correct Cursor position. set Cursor and print the string."

but this I need make for all object six times. Not one time:

if (Input == 1)
  {
    display.setCursor(13, 12);
    display.print("ONE");
  }
  if (Input == 2)
  {
    display.setCursor(13, 12);
    display.print("TWO");
  }
  if (Input == 3)
  {
    display.setCursor(11, 12);
    display.print("THREE");
  }
  if (Input == 4)
  {
    display.setCursor(12, 12);
    display.print("FOUR");
  }
  if (Input == 5)
  {
    display.setCursor(12, 12);
    display.print("FIVE");
  }
  if (Input == 6)
  {
    display.setCursor(13, 12);
    display.print("SIX");
  }

Im looking for options like this:

Center = (12,10); //X,Y
if (Input == 1)
  {
    display.print.Center("ONE");
  }
  if (Input == 2)
  {
    display.print.Center("TWO");
  }
  if (Input == 3)
  {
    display.print.Center("THREE");
  }
  if (Input == 4)
  {
    display.print.Center("FOUR");
  }
  if (Input == 5)
  {
    display.print.Center("FIVE");
  }
  if (Input == 6)
  {
    display.print.Center("SIX");
  }
4

Did you look at getTextBounds() ?

Yes, it is fairly complicated. Which is why you write a helper function once and use many times.

A function written in C is simple.
You require a lot of study to learn how to write your own Center class in C++

You could also think about designing a neater code sequence.

But learning how to write a helper function is a useful exercise. You can re-use it in different projects.
Ask if you want some help.

David.

5

Yes, I have found some topics with this function, but as You wrote, its fairly complicated :smiley:

Now I dont know how to make correct function with this getTexBounds()

This function allow me to set maximum area where letters can be displayed with "center"?

6 
void drawCentreString(const char *buf, int x, int y)
{
    int16_t x1, y1;
    uint16_t w, h;
    display.getTextBounds(buf, x, y, &x1, &y1, &w, &h); //calc width of new string
    display.setCursor(x - w / 2, y);
    display.print(buf);
}

call with:

    if (Input == 1) drawCentreString("ONE", 13, 12);
    else if (Input == 2) drawCentreString("TWO", 13, 12);
    else if (Input == 3) drawCentreString("THREE", 13, 12);
    ...

Untested. Helper expects a char array. If you use String class, you would write the equivalent function but with a String argument. e.g.

void drawCentreString(const String &buf, int x, int y)
{
    int16_t x1, y1;
    uint16_t w, h;
    display.getTextBounds(buf, x, y, &x1, &y1, &w, &h); //calc width of new string
    display.setCursor(x - w / 2, y);
    display.print(buf);
}
3 Likes
7

Thanks a lot :slight_smile:

8

One last question.

With this library: GitHub - jarzebski/Arduino-DS3231: DS3231 Real-Time-Clock

how can I use drawCentreString ??

28.10.2019 vs 2.2.19 (different width, DD.MM.YYYY_

same situation with time:
1:05 vs 11:05

9

Which display ?
What library(s) ?
Which Font ?

The GitHub examples appear to format the dates properly for the Serial Terminal.
i.e. use the library dateFormat()

Bog-standard Arduino print() makes horrible format e.g. 2.2.19

Centred text, Overwritten text, ... is very simple with standard Adafruit 7x5 Font

It gets fairly messy with variable-width Fonts that can only be printed in Transparent mode.
Yes, you can write helper functions once. Use many times in other projects.

David.