Chuck Norris jokes sketch for ESP32 and 128x64 OLED display

chuck_norris.ino

#include <U8g2lib.h>
#include <Wire.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

// ESP32 DevKitC has hardware I2C pins on 22 and 21
U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE, 22, 21);

StaticJsonDocument<8192> jsonDoc;
const char* lastText = "";

long lastLineChange = 0;
int startOffset = 64;

void prepareDisplay() {
  u8g2.setFont(u8g2_font_6x10_tf);
  u8g2.setFontRefHeightExtendedText();
  u8g2.setDrawColor(1);
  u8g2.setFontPosTop();
  u8g2.setFontDirection(0);
}

bool printWithOffset(const char* text, int offset) 
{
  bool printedSomething = false;
  int textLength = strlen(text);
  for (int i = 0; i < (textLength + 20) / 21; ++i) {
    if (10*i + offset < -20 || 10*i + offset > 74) {
      // We are far outside the visible region, no need to draw
      continue;
    }
    char buf[22];
    strncpy(buf, &text[i*21], 21);
    u8g2.drawUTF8(2, 10*i + offset, buf);
    printedSomething = true;
  }
  return printedSomething;
}

void setup() {
  WiFi.begin("5G COVID-19 Transmitter", "hunter2");
  while (WiFi.status() != WL_CONNECTED) {
    yield();
  }
  u8g2.begin();
  prepareDisplay();
}

void loop() {
  u8g2.clearBuffer();
  if (!printWithOffset(lastText, startOffset)) {
    // Since fetching is synchronous, we do it when the screen is blank
    HTTPClient http;
    http.begin("https://api.chucknorris.io/jokes/random");                                   
    if (http.GET() == 200) {
      if (!deserializeJson(jsonDoc, http.getString())) {
        lastText = jsonDoc["value"];
      }
    }
    // If we fail to fetch, we just keep the old text around
    http.end();
    startOffset = 64;
  } 
  u8g2.sendBuffer();

  long currentTime = millis();
  if (currentTime - lastLineChange > 50) {
    startOffset -= 1;
    lastLineChange = currentTime;
  }
}