From d9a7f40eb416b94379463c7267c805b1bb28e0df Mon Sep 17 00:00:00 2001
From: Roman <40754203+BohdanQQ@users.noreply.github.com>
Date: Sat, 14 Dec 2024 16:51:40 +0100
Subject: [PATCH] fix: Shortcuts not being disabled correctly when menu items
 are disabled  (#1992)

Fix crash on UNDO/REDO shortcut press when in "title screen"

### Problem description
ImHex crashes when (by default CTRL + Z/Y) undo/redo is pressed when on
"title"/"starting" screen (no file open, tested on Windows release build
and Linux [WSL] from-source build).

This is due to the shortcut's callback being called even if the
`provider` is `nullptr`. (see `createEditMenu` function).
Theoretically, this is prevented by the `enabledCallback` function
passsed to `addMenuItem`. In this case, though,
`addMenuItem` correctly propagates `enabledCallback` to menu item
creation but does not pass `enabledCallback` to
shortcut creation. Thus, when handling shortcuts, `enabledCallback` is
not used at all and the shortcut's callback
can be called in contradiction with its preconditions. (specified by
`enabledCallback`)

### Implementation description
The implementation wraps the callback in a check that decides whether
the shortcut is enabled or not.

(see changed files)
```c++
        auto callbackIfEnabled  = [enabledCallback, function]{ if (enabledCallback()) { function(); } };
```

This function is then passed along instead of the `function` (shortcut's
callback).

Alternatively, we can check for `nullptr` in the callback directly. This
would require modification of `createEditMenu`'s contents.
(I did not choose this implementation because I do not think it
addresses the root of the issue).

### Screenshots
None

### Additional things
I'm not sure how big of a deal it is but I am unsure whether I can
capture (`[enabledCallback, function]`) by reference or not.
---
 lib/libimhex/source/api/content_registry.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/libimhex/source/api/content_registry.cpp b/lib/libimhex/source/api/content_registry.cpp
index 867c2cc95..102009ac9 100644
--- a/lib/libimhex/source/api/content_registry.cpp
+++ b/lib/libimhex/source/api/content_registry.cpp
@@ -906,10 +906,11 @@ namespace hex {
             });
 
             if (shortcut != Shortcut::None) {
+                auto callbackIfEnabled  = [enabledCallback, function]{ if (enabledCallback()) { function(); } };
                 if (shortcut.isLocal() && view != nullptr)
-                    ShortcutManager::addShortcut(view, shortcut, unlocalizedMainMenuNames.back(), function);
+                    ShortcutManager::addShortcut(view, shortcut, unlocalizedMainMenuNames.back(), callbackIfEnabled);
                 else
-                    ShortcutManager::addGlobalShortcut(shortcut, unlocalizedMainMenuNames.back(), function);
+                    ShortcutManager::addGlobalShortcut(shortcut, unlocalizedMainMenuNames.back(), callbackIfEnabled);
             }
         }