Prolog鼠标悬停识别器

Question

如何在序言中为对象添加悬停识别器？我想要在用户用鼠标悬停对象时调用规则。

类似的东西：

send(S,recogniser,click_gesture(left,'',single,and(message(@prolog, add ,X, Y)))).

但对于鼠标悬停手势。

Answer 1

您必须处理鼠标事件。这是一个例子：我有一个按钮，当鼠标悬停在按钮上时，形状被修改。可以知道鼠标什么时候进入对象区域，什么时候离开。

:- pce_begin_class(my_button, button).

variable(enter, any, both, "flag pour le dessin lorsque la souris survole le bouton").

event(G, Ev:event) :->
    ( send(Ev, is_a, area_enter) ->
      send(G, slot, enter, in),
      send(G, redraw)

    ;   send(Ev, is_a, area_exit) ->
        send(G, slot, enter, out),
        send(G, redraw)
    ;  send_super(G, event, Ev)
    ).

initialise(P, Lbl):->
    send(P, send_super, initialise,Lbl),
    send(P, font, font(times, normal, 15)),
    send(P, compute),
    send(P, slot, enter, out).

% méthode d'affichage redéfinissable
'_redraw_area'(P, _A:area):->
        "Draw a "::
    % on affiche le texte
    get(P, label, Lbl),
    new(Str1, string(Lbl)),
    get_object(P, area, area(X0,Y0,W,H)),
    (      get(P, status, preview) -> X is X0 + 2, Y is Y0 + 2, Up = @off
    ;      X = X0, Y = Y0, Up = @on),

    (   get(P, slot, enter, out) ->  new(E, elevation(1)); new(E, elevation(3))),
    send(P, draw_box, X, Y, W, H, 5, E, Up),
    send(P, draw_text, Str1, font(times, normal, 15), X, Y, W, H, center, center),

    get(P, default_button, @on),
    X1 is X+3, Y1 is Y+3, W1 is W - 6, H1 is H- 6,
    send(P, save_graphics_state),
    send(P, graphics_state,texture := dotted),
    send(P, draw_box, X1, Y1, W1, H1, 5),
    send(P, restore_graphics_state).
:- pce_end_class.

Prolog鼠标悬停识别器

Prolog mouse hover recognizer

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gesture