Topic: [XDrX-Hook]WINDOWS hook (HOOK) function (1) - MASK the ESC key

[xdcad]

For information on using the WINDOWS message loop in LISP, see：

http://www.theswamp.org/index.php?topic=58729.0

Sometimes if you want your program not to be terminated by ESC, you can temporarily block the ESC key. The following code demonstrates how to define a hook (HOOK)


The following code is a switch command, which masks and releases ESC and is executed alternately. You can also modify VK_ESCAPE to other key codes to block other keys.


The hook function defined is:

Intercept the WM_KEYDOWN message. If the ESC key is pressed, the corresponding keyboard code is VK_ESCAPE (27), interrupt the message loop, and prevent AUTOCAD from knowing that this key press occurred.

Code - Auto/Visual Lisp: [Select]

1. (defun _mask-esc (hwnd msg wparam lparam ti pos)
2.      (cond ((= msg WM_KEYDOWN);;Keyboard press message
3.             (setq code wparam)
4.             (if (= code VK_ESCAPE)
5.               (xdrx_hook_block_messageloop t)
6.             )
7.            )
8.      )
9.    )
10.  

Implementation code (Switch Command)：

Code - Auto/Visual Lisp: [Select]

1. (defun c:tt ()
2.    (defun _mask-esc (hwnd msg wparam lparam ti pos)
3.      (cond ((= msg WM_CHAR)
4.             (setq code wparam)
5.             (if (= code VK_ESCAPE);;if ESC
6.               (xdrx_hook_block_messageloop t);;Block the message and let ACAD take over
7.             )
8.            )
9.      )
10.    )
11.    (xdrx_begin)
12.    (xd::hook:register "_mask-esc" nil "Mask ESC");Register hook function
13.    (if (not #xd_hook_mask_esc)
14.      (progn
15.        (xd::hook:enable "_mask-esc" t);;Hook function enabled
16.        (setq #xd_hook_mask_esc t)
17.      )
18.      (progn
19.        (xd::hook:enable "_mask-esc" nil);;Hook function disabled
20.        (setq #xd_hook_mask_esc nil)
21.      )
22.    )
23.    (xdrx_end)
24.    (princ)
25. )

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The above LISP code uses the XDRX-API, which can be downloaded from https://github.com/xdcad/XDrx-API

The XDRX API encapsulates AcDb, AcEd, AcGe, AcBr... C++ library, using C++ methods to develop LISP programs.Thousands of Lisp functions are available.
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