与OCaml图形互动

Question

嗨，我并不是很了解OCaml，但我必须使用标准图形模块而不是lablgtk来编写一个小型GUI，我想知道它是如何在Graphics中工作来监听事件，如按键和鼠标移动，文档似乎有点神秘，我可以给我一个小例子吗？

由于提前， 科林

Answer 1

该代码使用OCaml的图形模块显示在图形窗口中用户的鼠标位置和按键：

open Graphics 
open Printf 

(* Displays mouse position and keys pressed in the graphics window,                
    and exits if q is pressed. *) 
let rec loop() = 
    let e = wait_next_event [Mouse_motion; Key_pressed] in 

    let mouse_description = sprintf "Mouse position: %d,%d" e.mouse_x e.mouse_y in 
    let key_description = if e.keypressed then sprintf "Key %c was pressed" e.key else "" in 

    clear_graph(); 
    moveto 0 100; draw_string key_description; 
    moveto 0 0; draw_string mouse_description; 

    if e.key <> 'q' then loop() else() 

let() = 
    open_graph ""; 
    loop(); 
    close_graph();