/*
=== **Scrolling Text Demo ===
Part of API menu review
8/13/25 Sketch reviewed with Claude AI
*/

#include "U8g2lib.h"

// Constructor for U8g2lib
U8G2_SSD1306_128X64_NONAME_1_HW_I2C u8g2(U8G2_R0);

u8g2_uint_t offset;	// Tracks the current horizontal position for scrolling animation
u8g2_uint_t width; // Stores the total pixel width of the text string
// this example text is 82 characters long
const char *text = "We could never learn to be brave and patient if there were only joy in the world. ";

void setup() {
  u8g2.begin();
  u8g2.setFont(u8g2_font_inb16_mr);
  // width is a combination of 'text' length, which is 82
  // and the pixel width of the font, which is 14.
  width = u8g2.getUTF8Width(text); // width: 82 x 14 = 1148
  u8g2.setFontMode(0); // enable transparent mode, which is faster
}

void loop(void) {
  u8g2_uint_t x; // declare a local variable x for horizontal positioning

  u8g2.firstPage();
  do {
    // draw the scrolling text at current offset
    x = offset;
    u8g2.setFont(u8g2_font_inb16_mr); // set the target font

    do { // repeated drawing of the scrolling text...
      // x = horizontal, y = vertical, text = *string
      u8g2.drawUTF8(x, 30, text);	// draw the scolling text
      x += width;	// add the pixel width of the scrolling text
      // draw again until the complete display is filled
      // while x < 128
    } while (x < u8g2.getDisplayWidth()); // getDisplayWidth() = 128
    /*
    Lines 35-41: Inner loop that draws the text multiple times across the screen:
      Draws the text at position (x, 30) - 30 pixels from top
      Increases x by the text width to position the next copy
      Continues until the entire 128-pixel width is filled
      This creates seamless scrolling by having multiple copies of the text
    */



    u8g2.setFont(u8g2_font_inb16_mr);	// draw the current pixel width
    u8g2.setCursor(0, 58);
    u8g2.print(width); // this value must be lesser than 128 unless U8G2_16BIT is set

  // Complete the page rendering system - 
  // this actually sends the drawn content to the display.
  } while (u8g2.nextPage());

  // Decreases offset by 10 pixels (moves text left)
  // When offset becomes more negative than the text width, reset to 0
  // This creates continuous left-scrolling motion
  offset -= 10;	// speed adjust, lower number slower, higher number faster
  if ((u8g2_uint_t) offset < (u8g2_uint_t) - width)
    offset = 0;	// start over again

  delay(50); // > value, can be used to slow down scrolling
}