LibGUI: Allow Shortcuts to have a mouse button associated with them

A Shortcut can now be either have a keyboard key, or a mouse button,
along with any modifiers.

Decided to add an extra type field instead of subclassing, which means
callers will have to be a little careful before accessing a particular
input method's "key", but it keeps things simple for now.

Userland/Libraries/LibGUI/Shortcut.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2022, Geordie Hall <me@geordiehall.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -24,10 +25,17 @@ String Shortcut::to_string() const
     if (m_modifiers & Mod_Super)
         parts.append("Super");
 
-    if (auto* key_name = key_code_to_string(m_key))
+    if (m_type == Type::Keyboard) {
-        parts.append(key_name);
+        if (auto* key_name = key_code_to_string(m_keyboard_key))
-    else
+            parts.append(key_name);
-        parts.append("(Invalid)");
+        else
+            parts.append("(Invalid)");
+    } else {
+        if (m_mouse_button != MouseButton::None)
+            parts.append(String::formatted("Mouse {}", mouse_button_to_string(m_mouse_button)));
+        else
+            parts.append("(Invalid)");
+    }
 
     StringBuilder builder;
     builder.join('+', parts);

Userland/Libraries/LibGUI/Shortcut.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2022, Geordie Hall <me@geordiehall.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -8,6 +9,7 @@
 
 #include <AK/Traits.h>
 #include <Kernel/API/KeyCode.h>
+#include <LibGUI/Event.h>
 
 namespace GUI {
 
@@ -15,30 +17,62 @@ class Shortcut {
 public:
     Shortcut() = default;
     Shortcut(u8 modifiers, KeyCode key)
-        : m_modifiers(modifiers)
+        : m_type(Type::Keyboard)
-        , m_key(key)
+        , m_modifiers(modifiers)
+        , m_keyboard_key(key)
     {
     }
     Shortcut(KeyCode key)
-        : m_modifiers(0)
+        : m_type(Type::Keyboard)
-        , m_key(key)
+        , m_modifiers(0)
+        , m_keyboard_key(key)
+    {
+    }
+    Shortcut(u8 modifiers, MouseButton button)
+        : m_type(Type::Mouse)
+        , m_modifiers(modifiers)
+        , m_mouse_button(button)
+    {
+    }
+    Shortcut(MouseButton button)
+        : m_type(Type::Mouse)
+        , m_modifiers(0)
+        , m_mouse_button(button)
     {
     }
 
-    bool is_valid() const { return m_key != KeyCode::Key_Invalid; }
+    enum class Type : u8 {
-    u8 modifiers() const { return m_modifiers; }
+        Keyboard,
-    KeyCode key() const { return m_key; }
+        Mouse,
+    };
+
     String to_string() const;
+    Type type() const { return m_type; }
+    bool is_valid() const { return m_type == Type::Keyboard ? (m_keyboard_key != Key_Invalid) : (m_mouse_button != MouseButton::None); }
+    u8 modifiers() const { return m_modifiers; }
+
+    KeyCode key() const
+    {
+        VERIFY(m_type == Type::Keyboard);
+        return m_keyboard_key;
+    }
+
+    MouseButton mouse_button() const
+    {
+        VERIFY(m_type == Type::Mouse);
+        return m_mouse_button;
+    }
 
     bool operator==(Shortcut const& other) const
     {
-        return m_modifiers == other.m_modifiers
+        return m_modifiers == other.m_modifiers && m_type == other.m_type && m_keyboard_key == other.m_keyboard_key && m_mouse_button == other.m_mouse_button;
-            && m_key == other.m_key;
     }
 
 private:
+    Type m_type { Type::Keyboard };
     u8 m_modifiers { 0 };
-    KeyCode m_key { KeyCode::Key_Invalid };
+    KeyCode m_keyboard_key { KeyCode::Key_Invalid };
+    MouseButton m_mouse_button { MouseButton::None };
 };
 
 }
@@ -49,7 +83,12 @@ template<>
 struct Traits<GUI::Shortcut> : public GenericTraits<GUI::Shortcut> {
     static unsigned hash(const GUI::Shortcut& shortcut)
     {
-        return pair_int_hash(shortcut.modifiers(), shortcut.key());
+        auto base_hash = pair_int_hash(shortcut.modifiers(), (u32)shortcut.type());
+        if (shortcut.type() == GUI::Shortcut::Type::Keyboard) {
+            return pair_int_hash(base_hash, shortcut.key());
+        } else {
+            return pair_int_hash(base_hash, shortcut.mouse_button());
+        }
     }
 };