Best way to print letters with strikethrough

Projects Programming
1

I have an ESP32 powered epaper display. I'd like to display.print letters with strikethrough and I'm looking at ways to achieve this.

I could create a custom set of letters (e.g. using https://tchapi.github.io/Adafruit-GFX-Font-Customiser/ ) - but is there a better option? e.g. being able to draw a line through text - although i'd only want it to be the width of the sentance, which may change.

2

Hi @jimbo101 ,

welcome to the forum!

I think it's a tradeoff between

  • additional memory consumption and time to create the font and
  • effort to implement a strike-through routine

In a different thread related to tft displays I used this function

   tft.getTextBounds(stringText, x,y, &x1, &y1, &w, &h);

to get the boundary coordinates of a given string.

If that's available for your epaper it might be a reasonable (and interesting :wink: ) solution to develop a function.

ec2021

3

Thanks, much appreciated. I will have a play with this function later to see if I can get it to work for my use case and report back!

4

Welcome!

If you use proportional fonts the different characters have specific widths. This is taken care of by the getTextBounds() function.

I have prepared an example for a tft display:

https://wokwi.com/projects/423332516171588609

/*

  Forum: https://forum.arduino.cc/t/best-way-to-print-letters-with-strikethrough/1355282
  Wokwi: https://wokwi.com/projects/423332516171588609

  2025-02-20
  ec2021

  Realization of a simple "Strike Through" function for TFT displays
  Known limitation: String must fit in one line 

*/

#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_ILI9341.h"

#define TFT_DC 9
#define TFT_CS 10
Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC);

void Print(String txt, int atX, int atY, int tSize, uint16_t col){
        int boxX, boxY, width, height;
        tft.setCursor(atX, atY);
        tft.setTextColor(col);
        tft.setTextSize(tSize);
        tft.println(txt);
        tft.getTextBounds(txt,atX,atY, &boxX, &boxY, &width, &height);
        tft.drawFastHLine(boxX,boxY+height/2,width,col);
};

void setup() {
  tft.begin();
  tft.setRotation(0);
  Print("Strike Through",10,10, 1, ILI9341_RED);
  Print("Strike Through",10,30, 2, ILI9341_BLUE);
  tft.setRotation(1);
  Print("Strike Through",10, 120, 3, ILI9341_GREEN);
}

void loop() {
}

The example does not deal with text wrapping ...

Good luck!
ec2021