Text wrapping for the esphome display api

text_wrap.cpp

#include <vector>
#include <string>
#include <sstream>
#include "esphome/components/display/display_buffer.h"
#include "text_wrap.h"

using namespace esphome;
using namespace esphome::display;

void wrap_text(DisplayBuffer* it, int x, int y, const char* text, Font* font, TextAlign align, float line_height) {
    // Calculate the bounds of a single space character
    int space_x1, space_y1, space_width, space_height;
    it->get_text_bounds(x, y, " ", font, align, &space_x1, &space_y1, &space_width, &space_height);

    // Break text into words
    std::vector<std::string> words;
    std::stringstream ss(text);
    std::string word;
    while (std::getline(ss, word, ' ')) {
        words.push_back(word);
    }

    // Initialize variables for the wrapped text
    int line_x = x;
    int line_y = y;
    int word_x1, word_y1, word_width, word_height;
    std::string line;

    // Iterate through the words and wrap them
    for (const auto& w : words) {
        it->get_text_bounds(line_x, line_y, w.c_str(), font, align, &word_x1, &word_y1, &word_width, &word_height);

        if (line_x + word_width >= it->get_width()) {
            // Print the current line and move to the next line
            it->printf(x, line_y, font, align, "%s", line.c_str());
            line_y += static_cast<int>(word_height * line_height);
            line_x = x;

            // Clear the line buffer
            line.clear();
        }

        // Add the word to the line buffer and move the cursor
        line += w;
        line_x += word_width + space_width;

        // If it's not the last word, add a space
        if (!line.empty() && &w != &words.back()) {
            line += " ";
        }
    }

    // Print the last line
    if (!line.empty()) {
        it->printf(x, line_y, font, align, "%s", line.c_str());
    }
}

text_wrap.h

#pragma once

#include "esphome/components/display/display_buffer.h"

void wrap_text(
    esphome::display::DisplayBuffer* it, int x, int y,
    const char* text, esphome::display::Font* font,
    esphome::display::TextAlign align, float line_height
);

Put the files in the esphome folder of your home assistant configuration.

Usage in yaml:

esphome:
  # ...
  includes:
    - text_wrap.h
    - text_wrap.cpp


display:
  - platform: waveshare_epaper  # or any other display platform
    # ...
    lambda: |-
      wrap_text(&it, 8, 80, "Long text here that needs wrapping", id(fontId), TextAlign::TOP_LEFT, 1);

Thanks for this, it was very helpful. I had an urgent priority to add dad jokes to my e-paper display, least I die of boredom.

Note, I had to add #include esphome/components/font/font.h to text_wrap.cpp because it would error out on lack of reference to Font. I also needed to change Font* font to esphome::display::BaseFont* font on the wrap_text function for the same reason.

Perhaps you have a reference to Font somewhere else in your ESPHome config?

Anyway, it works like a charm! Thanks again.

This is great @alvesvaren. I have built on what you wrote, to make a printf format compatible version, that also allows you to specify a box anywhere on the screen (not just wrapping at the screen edge). Would you be willing for this to be added to the official esphome distribution?

If so, I am happy to create the pull request.

@davet2001 Sure, go for it! I just put this together pretty quickly for a project I had but it would be great to have it in esphome directly