inst/examples/ex-tic-tac-toe.R

In jverzani/gWidgetsWWW2.rapache: Toolkit implementation of the gWidgets API for use with web pages

## A response to a stackoverflow question. A tic-tac-toe game where
## each click alternates "x" and "o".

w <- gwindow("Tic-Tac-Toe")
sb <- gstatusbar("Powered by gWidgetsWWW2 and Rook", cont=w)
g <- gvbox(cont=w)
ghtml("Tic-Tac-Toe, three in a row", cont=g)


## sizing
margin <- 10
sz <- 130
width <- height <- 3*sz + 2 * margin

state <- matrix(character(9), nrow=3)
x_move <- TRUE
sym <- c("o", "x")


cnv <- gcanvas(width=width, height=height, cont=g)

##' make the game board
make_board <- function() {
  for(i in seq(margin + sz, margin + 2*sz, by=sz)) {
    cnv_lines(cnv,
              c(margin, width-margin),
              c(i, i)
              )
    cnv_lines(cnv, c(i, i), c(margin, width-margin))
  }
}

##' function to draw an x in cell i,j
draw_x <- function(i, j) {
  delta <- sz/10
  cnv_lines(cnv,
            margin + sz *c(i-1, i) + delta*c(1,-1),
            margin + sz *c(j-1, j) + delta*c(1,-1)
            )
  cnv_lines(cnv,
            margin + sz *c(i-1, i) + delta*c(1,-1),
            margin + sz *c(j, j-1) + delta*c(-1,1))

}

##' function to draw an "o" in cell i,j
draw_o <- function(i, j) {
  cnv_circle(cnv,
             margin + (i-1/2)*sz,
             margin + (j-1/2)*sz, r = (3/8)*sz)
}

##' what to do when there is a winner
notify_winner <- function(mark) {
  if(mark == "x") {
    svalue(sb) <- "Congrats, x won"
  } else {
    svalue(sb) <- "Congrats, o won"
  }

}

##' check if there is a winner;
##' if so notify, block handlers and return TRUE;
##' else return FALSE
check_winner <- function() {
  ## x
  is_winner <- function(mark) {
    any(colSums(state == mark) == 3)  ||
    any(rowSums(state == mark) == 3) ||
    sum((state == mark)[c(1,5,9)]) == 3 ||
    sum((state == mark)[c(3,5,7)]) == 3
  }
  if(is_winner("x")) {
    notify_winner("x")
    block_handlers(cnv)
    return(TRUE)
  } else if(is_winner("o")) {
    notify_winner("o")
    block_handlers(cnv)
    return(TRUE)
  }
  return(FALSE)
}


##' What to do when a cell is clicked
addHandlerClicked(cnv, handler=function(h,...) {
  ## X,Y components in "pixel" coordinates in [0,width] x [0, height]; with (0,0) in upper left
  i <- 1 + (h$X - margin) %/% sz
  j <- 1 + (h$Y - margin) %/% sz

  if(i %in% 1:3 && j %in% 1:3) {
    if(state[i,j] == "") {
      state[i,j] <<- sym[1 + x_move]
      if(x_move) {
        draw_x(i,j)
      } else {
        draw_o(i,j)
      }
      x_move <<- !x_move
      if(!check_winner())
        svalue(sb) <- "Click to move"
    } else {
      svalue(sb) <- "Already selected that cell"
    }
  }

})


## Start
make_board()
svalue(sb) <- "Click to  move"