gtk2/demos/gtk-demo/sliding_puzzle.c

/* Sliding puzzle
 *
 * This demo demonstrates how to use gestures and paintables to create a
 * small sliding puzzle game.
 *
 */

#include <gtk/gtk.h>

/* Include the header for the puzzle piece */
#include "puzzlepiece.h"

static GtkWidget *window = NULL;
static GtkWidget *frame = NULL;

static gboolean solved = TRUE;
static guint width = 6;
static guint height = 6;
static guint pos_x;
static guint pos_y;

static gboolean
move_puzzle (GtkWidget *grid,
             int        dx,
             int        dy)
{
  GtkWidget *pos, *next;
  GdkPaintable *piece;
  guint next_x, next_y;

  /* We don't move anything if the puzzle is solved */
  if (solved)
    return FALSE;

  /* Return FALSE if we can't move to where the call 
   * wants us to move.
   */
  if ((dx < 0 && pos_x < -dx) ||
      dx + pos_x >= width ||
      (dy < 0 && pos_y < -dy) ||
      dy + pos_y >= height)
    return FALSE;

  /* Compute the new position */
  next_x = pos_x + dx;
  next_y = pos_y + dy;

  /* Get the current and next image */
  pos = gtk_grid_get_child_at (GTK_GRID (grid), pos_x, pos_y);
  next = gtk_grid_get_child_at (GTK_GRID (grid), next_x, next_y);

  /* Move the displayed piece. */
  piece = gtk_image_get_paintable (GTK_IMAGE (next));
  gtk_image_set_from_paintable (GTK_IMAGE (pos), piece);
  gtk_image_clear (GTK_IMAGE (next));

  /* Update the current position */
  pos_x = next_x;
  pos_y = next_y;

  /* Return TRUE because we successfully moved the piece */
  return TRUE;
}

static void
shuffle_puzzle (GtkWidget *grid)
{
  guint i, n_steps;

  /* Do this many random moves */
  n_steps = width * height * 50;

  for (i = 0; i < n_steps; i++)
    {
      /* Get a random number for the direction to move in */
      switch (g_random_int_range (0, 4))
        {
        case 0:
          /* left */
          move_puzzle (grid, -1, 0);
          break;

        case 1:
          /* up */
          move_puzzle (grid, 0, -1);
          break;

        case 2:
          /* right */
          move_puzzle (grid, 1, 0);
          break;

        case 3:
          /* down */
          move_puzzle (grid, 0, 1);
          break;

        default:
          g_assert_not_reached ();
          continue;
        }
    }
}

static gboolean
check_solved (GtkWidget *grid)
{
  GtkWidget *image;
  GdkPaintable *piece;
  guint x, y;

  /* Nothing to check if the puzzle is already solved */
  if (solved)
    return TRUE;

  /* If the empty cell isn't in the bottom right,
   * the puzzle is obviously not solved */
  if (pos_x != width - 1 ||
      pos_y != height - 1)
    return FALSE;

  /* Check that all pieces are in the right position */
  for (y = 0; y < height; y++)
    {
      for (x = 0; x < width; x++)
        {
          image = gtk_grid_get_child_at (GTK_GRID (grid), x, y);
          piece = gtk_image_get_paintable (GTK_IMAGE (image));

          /* empty cell */
          if (piece == NULL)
            continue;

          if (gtk_puzzle_piece_get_x (GTK_PUZZLE_PIECE (piece)) != x ||
              gtk_puzzle_piece_get_y (GTK_PUZZLE_PIECE (piece)) != y)
            return FALSE;
        }
    }

  /* We solved the puzzle!
   */
  solved = TRUE;

  /* Fill the empty cell to show that we're done.
   */
  image = gtk_grid_get_child_at (GTK_GRID (grid), 0, 0);
  piece = gtk_image_get_paintable (GTK_IMAGE (image));

  piece = gtk_puzzle_piece_new (gtk_puzzle_piece_get_puzzle (GTK_PUZZLE_PIECE (piece)),
                                pos_x, pos_y,
                                width, height);
  image = gtk_grid_get_child_at (GTK_GRID (grid), pos_x, pos_y);
  gtk_image_set_from_paintable (GTK_IMAGE (image), piece);

  return TRUE;
}

static gboolean
puzzle_key_pressed (GtkEventControllerKey *controller,
                    guint                  keyval,
                    guint                  keycode,
                    GdkModifierType        state,
                    GtkWidget             *grid)
{
  int dx, dy;

  dx = 0;
  dy = 0;

  switch (keyval)
    {
    case GDK_KEY_KP_Left:
    case GDK_KEY_Left:
      /* left */
      dx = -1;
      break;

    case GDK_KEY_KP_Up:
    case GDK_KEY_Up:
      /* up */
      dy = -1;
      break;

    case GDK_KEY_KP_Right:
    case GDK_KEY_Right:
      /* right */
      dx = 1;
      break;

    case GDK_KEY_KP_Down:
    case GDK_KEY_Down:
      /* down */
      dy = 1;
      break;

    default:
      /* We return FALSE here because we didn't handle the key that was pressed */
      return FALSE;
    }

  if (!move_puzzle (grid, dx, dy))
    {
      /* Make the error sound and then return TRUE.
       * We handled this key, even though we didn't
       * do anything to the puzzle.
       */
      gtk_widget_error_bell (grid);
      return TRUE;
    }

  check_solved (grid);

  return TRUE;
}

static void
start_puzzle (GdkPaintable *puzzle)
{
  GtkWidget *image, *grid;
  GtkEventController *controller;
  guint x, y;

  /* Remove the old grid (if there is one) */
  grid = gtk_bin_get_child (GTK_BIN (frame));
  if (grid)
    gtk_container_remove (GTK_CONTAINER (frame), grid);

  /* Create a new grid */
  grid = gtk_grid_new ();
  gtk_widget_set_can_focus (grid, TRUE);
  gtk_container_add (GTK_CONTAINER (frame), grid);

  /* Add a key event controller so people can use the arrow
   * keys to move the puzzle */
  controller = gtk_event_controller_key_new ();
  g_signal_connect (controller, "key-pressed",
                    G_CALLBACK (puzzle_key_pressed),
                    grid);
  gtk_widget_add_controller (GTK_WIDGET (grid), controller);

  /* Make sure the cells have equal size */
  gtk_grid_set_row_homogeneous (GTK_GRID (grid), TRUE);
  gtk_grid_set_column_homogeneous (GTK_GRID (grid), TRUE);

  /* Reset the variables */
  solved = FALSE;
  pos_x = width - 1;
  pos_y = height - 1;

  /* add an image for every cell */
  for (y = 0; y < height; y++)
    {
      for (x = 0; x < width; x++)
        {
          GdkPaintable *piece;

          /* Don't paint anything for the lsiding part of the video */
          if (x == pos_x && y == pos_y)
            piece = NULL;
          else
            piece = gtk_puzzle_piece_new (puzzle,
                                          x, y,
                                          width, height);
          image = gtk_image_new_from_paintable (piece);
          gtk_image_set_keep_aspect_ratio (GTK_IMAGE (image), FALSE);
          gtk_image_set_can_shrink (GTK_IMAGE (image), TRUE);
          gtk_grid_attach (GTK_GRID (grid),
                           image,
                           x, y,
                           1, 1);
        }
    }

  shuffle_puzzle (grid);
}

GtkWidget *
do_sliding_puzzle (GtkWidget *do_widget)
{
  GdkPaintable *puzzle;

  if (!window)
    {
      window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
      gtk_window_set_display (GTK_WINDOW (window),
                              gtk_widget_get_display (do_widget));
      gtk_window_set_title (GTK_WINDOW (window), "Sliding Puzzle");
      gtk_window_set_default_size (GTK_WINDOW (window), 400, 300);
      g_signal_connect (window, "destroy",
                        G_CALLBACK (gtk_widget_destroyed), &window);

      puzzle = GDK_PAINTABLE (gdk_texture_new_from_resource ("/sliding_puzzle/portland-rose.jpg"));

      frame = gtk_aspect_frame_new (NULL, 0.5, 0.5, (float) gdk_paintable_get_intrinsic_aspect_ratio (puzzle), FALSE);
      gtk_container_add (GTK_CONTAINER (window), frame);

      /* Start a puzzle with a default image */
      
      start_puzzle (puzzle);
      g_object_unref (puzzle);
    }

  if (!gtk_widget_get_visible (window))
    gtk_widget_show (window);
  else
    gtk_widget_destroy (window);

  return window;
}