window

Exmaple One : init

init window and line drwaing

how init window ?

• define struct window

struct s_window {
	void	*mlx;
	void	*win;
	void	*img;
	int		*data;
	int		bpp;
	int		size_line;
	int		endian;
} t_window;

• call mlx.init() and assign to window.mlx

# define WIDTH 800
# define HEIGHT 600

int main(void)
{
    t_window	*window; // declare window struct

    window = (t_window *)malloc(sizeof(t_window)); // allocate memory for window struct
    window->mlx = mlx_init(); // init mlx
    window->win = mlx_new_window(window.mlx, WIDTH, HEIGHT, "Fractol"); // init window
    window->img = mlx_new_image(window.mlx, WIDTH, HEIGHT); // init image
    window->data = (int *) mlx_get_data_addr(window.img, &window.bpp, &window.size_line, &window.endian); // get data address

}

• explain all above functions ?

  • mlx_init() is a function that initialize mlx library
  • mlx_new_window() is a function that initialize window
  • mlx_new_image() is a function that initialize image
  • mlx_get_data_addr() is a function that get data address of image
  • window.bpp is the number of bits per pixel
  • window.size_line is the number of bytes in a line
  • window.endian is the endian of image

• Why I add (int *) to mlx_get_data_addr?

  • Without (int *) it will return a pointer to the first element of the array.

  window->data[(y * WIDTH) + x][0] = 0xDD;
  window->data[(y * WIDTH) + x][1] = 0x99;
  window->data[(y * WIDTH) + x][2] = 0x33;
  window->data[(y * WIDTH) + x][3] = 0xFF;

  • With (int *) it will return a pointer to the all elements of the array.

  window->data[(y * WIDTH) + x] = 0xDD9933;

  before i forget at struct data type is int pointer if i use (int *)

Get_data_addr

• get_data_addr() is a function that get data address of image bpp, size_line, endian

• Why need to get bpp, size_line, endian ?

  • bpp is the number of bits per pixel
  • size_line is the number of bytes in a line
  • endian is the endian of image

• Echa pixel is a 4 byte array

  • [0] is the red value
  • [1] is the green value
  • [2] is the blue value
  • [3] is the alpha value

• Why alpha value is the last byte ?

  • Because alpha value is the transparency of the pixel

• How many pixel in a window ?

  • WIDTH * HEIGHT = 800 * 600
  • 800 * 600 * 4 = 240000 // beacuse each pixel is a 4 byte array
  • 240000 / 4 = 60000

• How I can get Loction for echa pixel ?

  • (y * WIDTH) + x is the location of echa pixel
  • y is the row
  • x is the column

• How access to pixel?

  window->data[(y * WIDTH) + x] = 0xDD9933;

• How drawing line from (x0, y0)->(x1, y1)?

  int x0 = 0;
  int y0 = 0;
  int x1 = WIDTH;
  int y1 = HEIGHT;
  
  while (y0 < y1)
  {
      window->data[(y0 * WIDTH) + x0] = 0xDD9933;
      y0++;
      x0++;
  }
  
  mlx_put_image_to_window(window->mlx, window->win, window->img, 0, 0);

• What is mlx_put_image_to_window ?

  • mlx_put_image_to_window is a function that put image to window
  • window->mlx is the mlx library
  • window->win is the window
  • window->img is the image
  • 0 is the x location of image
  • 0 is the y location of image