display_sample.c

#include <stdio.h>
#include <math.h>

#define COL 64
#define ROW 24

FILE* f;

/* 画面を白く塗りつぶす */
void clear()
{
  int i;
  char n = 0x00;
  fseek(f, 0, SEEK_SET);
  for (i = 0; i<COL*ROW; i++)
    fwrite(&n, sizeof(char), 1, f);
}

/* 画面を黒く塗りつぶす */
void fill()
{
  int i;
  char n = 0xFF;
  fseek(f, 0, SEEK_SET);
  for (i = 0; i<COL*ROW; i++)
    fwrite(&n, sizeof(char), 1, f);
}

/* XY座標をバイト・ビットインデックスに変換する */
void xy2i(int x, int y, int* by, int* bi)
{
  int a = y * COL + x;
  *by = a / 8;
  *bi = a % 8;
}

/* 点を描く */
void point(int x, int y, int flag)
{
  int by, bi;
  char b;
  xy2i(x, y, &by, &bi);
  if (by < 0 || by > COL*ROW / 8) {
    return;
  }
  if (x < 0 || x >= COL)
    return;
  if (y < 0 || y >= ROW)
    return;
  fseek(f, by, SEEK_SET);
  fread(&b, sizeof(char), 1, f);
  if (flag)
    b |= (1 << (7 - bi));
  else
    b &= ~(1 << (7 - bi));
  fseek(f, by, SEEK_SET);
  fwrite(&b, sizeof(char), 1, f);
}

/* 直線を描く */
void line(int x1, int y1, int x2, int y2)
{
  int x, y;
  int dx, dy;
  dx = abs(x2 - x1);
  dy = abs(y2 - y1);

  if (dx > dy) {
    if (x1 > x2) {
      x = x1;
      x1 = x2;
      x2 = x;
      y = y1;
      y1 = y2;
      y2 = y;
    }
    for (x = x1 >= 0 ? x1 : 0; x <= x2 && x < COL; x++) {
      point(x, (y2 - y1) * (x - x1) / dx + y1, 1);
    }
  }
  else {
    if (y1 > y2) {
      x = x1;
      x1 = x2;
      x2 = x;
      y = y1;
      y1 = y2;
      y2 = y;
    }
    for (y = y1 >= 0 ? y1 : 0; y <= y2 && y < ROW; y++) {
      point((x2 - x1) * (y - y1) / dy + x1, y, 1);
    }
  }
}

/* 矩形を描く */
void rect(int x, int y, int w, int h)
{
  line(x, y, x + w, y);
  line(x, y, x, y + h);
  line(x + w, y, x + w, y + h);
  line(x, y + h, x + w, y + h);
}

void load_bitmap(char* path)
{
  FILE* ff = fopen(path, "r");
  char line[COL + 2];
  int ln = 0;
  while (fgets(line, COL + 2, ff) != NULL) {
    for (int i=0; i<COL && strlen(line); i++) {
      point(i, ln, line[i] == '*' ? 1 : 0);
    }
    ln++;
    if (ln > ROW)
      break;
  }
  fclose(ff);
}

int main()
{
  f = fopen("fb0.bin", "w+b");
  clear();
  // load_bitmap("image.txt");
  fclose(f);

  for (int i=0; i<COL * 100; i++) {
    f = fopen("fb0.bin", "w+b");
    clear();
    line(0, ROW/2, COL - 1, ROW/2);
    double xang;
    double y;
    int px, py;
    int yy;
    for (int x=0; x<COL + i; x++) {
      xang = x * 3.141592 / 16;
      y = sin(xang);
      y *= 8; 
      if (x > 0) {
        line(px - i, py + ROW/2, x - i, (int)y + ROW/2);
      }
      if (x - i == 10) {
        yy = (int)y + ROW / 2;
      }
      px = x;
      py = (int)y;
    }
    rect(10, yy, 3, 3);
    fclose(f);
    sleep(50);
  }

  return 0;
}