Text c scroll in c with rpi-rgb-led-matrix and P10 64x64

/* Text c scroll in c with  rpi-rgb-led-matrix   and P10 64x64 A.Villanueva
 * https://github.com/hzeller/rpi-rgb-led-matrix
 *- mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
 *
 * Using the C-API of this library.
 *
 */
#include "led-matrix-c.h"

#include <stdio.h>
#include <string.h>
#include <unistd.h>

int main(int argc, char **argv) {
  struct RGBLedMatrixOptions options;
  struct RGBLedMatrix *matrix;
  struct LedCanvas *offscreen_canvas;
  const char FONT[] ="../fonts/texgyre-27.bdf";
  const char *message="HOLA COMO ESTAS ";
  uint8_t r=0,g=255,b=0;//Color RGB
  int width, height;
  int x=128, y=32, i;

  memset(&options, 0, sizeof(options));
  options.rows = 64;
  options.cols =64;
  options.chain_length = 6;

  /* This supports all the led commandline options. Try --led-help */
  matrix = led_matrix_create_from_options(&options, &argc, &argv);
  if (matrix == NULL)
    return 1;

  /* Let's do an example with double-buffering. We create one extra
   * buffer onto which we draw, which is then swapped on each refresh.
   * This is typically a good aproach for animations and such.
   */
  offscreen_canvas = led_matrix_create_offscreen_canvas(matrix);

  led_canvas_get_size(offscreen_canvas, &width, &height);

  fprintf(stderr, "Size: %dx%d. Hardware gpio mapping: %s\n",
          width, height, options.hardware_mapping);


// Draw text, a standard NUL terminated C-string encoded in UTF-8,
// with given "font" at "x","y" with "color".
// Draw text as above, but vertically (top down).
// The text is a standard NUL terminated C-string encoded in UTF-8.
// "font, "x", "y", "color" and "background_color" are same as DrawText().
// "kerning_offset" allows for additional spacing between characters (can be
// negative).
// Returns font height to advance up on the screen.
//int vertical_draw_text(struct LedCanvas *c, struct LedFont *font, int x, int y,
//                       uint8_t r, uint8_t g, uint8_t b,
//                       const char *utf8_text, int kerning_offset = 0)

    for (int temp=0;temp<1000;temp++){


    printf ("how many pixels we advanced on the screen = %d \n",draw_text( offscreen_canvas,load_font(FONT), x, y,r,g,b ,message,0));


    /* Now, we swap the canvas. We give swap_on_vsync the buffer we
     * just have drawn into, and wait until the next vsync happens.
     * we get back the unused buffer to which we'll draw in the next
     * iteration.
     */
    offscreen_canvas = led_matrix_swap_on_vsync(matrix, offscreen_canvas);
  }
  led_matrix_delete(matrix);

  return 0;
}