LibGUI: Add GActionGroup, a way to group a bunch of GActions.

This can be used to make a bunch of actions mutually exclusive.
This patch only implements the exclusivity behavior for buttons.

Applications/FileManager/main.cpp

@@ -2,6 +2,7 @@
 #include <AK/FileSystemPath.h>
 #include <LibCore/CUserInfo.h>
 #include <LibGUI/GAction.h>
+#include <LibGUI/GActionGroup.h>
 #include <LibGUI/GApplication.h>
 #include <LibGUI/GBoxLayout.h>
 #include <LibGUI/GFileSystemModel.h>
@@ -108,18 +109,21 @@ int main(int argc, char** argv)
 
     view_as_table_action = GAction::create("Table view", { Mod_Ctrl, KeyCode::Key_L }, GraphicsBitmap::load_from_file("/res/icons/16x16/table-view.png"), [&](const GAction&) {
         directory_view->set_view_mode(DirectoryView::ViewMode::List);
-        view_as_icons_action->set_checked(false);
         view_as_table_action->set_checked(true);
     });
     view_as_table_action->set_checkable(true);
-    view_as_table_action->set_checked(false);
 
     view_as_icons_action = GAction::create("Icon view", { Mod_Ctrl, KeyCode::Key_I }, GraphicsBitmap::load_from_file("/res/icons/16x16/icon-view.png"), [&](const GAction&) {
         directory_view->set_view_mode(DirectoryView::ViewMode::Icon);
-        view_as_table_action->set_checked(false);
         view_as_icons_action->set_checked(true);
     });
     view_as_icons_action->set_checkable(true);
+
+    auto view_type_action_group = make<GActionGroup>();
+    view_type_action_group->set_exclusive(true);
+    view_type_action_group->add_action(*view_as_table_action);
+    view_type_action_group->add_action(*view_as_icons_action);
+
     view_as_icons_action->set_checked(true);
 
     auto copy_action = GAction::create("Copy", GraphicsBitmap::load_from_file("/res/icons/16x16/edit-copy.png"), [](const GAction&) {

Libraries/LibGUI/GAbstractButton.h

@@ -29,7 +29,8 @@ public:
     virtual void click() = 0;
     virtual const char* class_name() const override { return "GAbstractButton"; }
     virtual bool accepts_focus() const override { return true; }
-    virtual bool supports_keyboard_activation() const { return true; }
+    virtual bool supports_keyboard_activation() const override { return true; }
+    virtual bool is_uncheckable() const { return true; }
 
 protected:
     explicit GAbstractButton(GWidget* parent);

Libraries/LibGUI/GAction.cpp

@@ -1,4 +1,5 @@
 #include <LibGUI/GAction.h>
+#include <LibGUI/GActionGroup.h>
 #include <LibGUI/GApplication.h>
 #include <LibGUI/GButton.h>
 #include <LibGUI/GMenuItem.h>
@@ -105,6 +106,17 @@ void GAction::set_checked(bool checked)
     if (m_checked == checked)
         return;
     m_checked = checked;
+
+    if (m_checked && m_action_group) {
+        m_action_group->for_each_action([this](auto& other_action) {
+            if (this == &other_action)
+                return IterationDecision::Continue;
+            if (other_action.is_checkable())
+                other_action.set_checked(false);
+            return IterationDecision::Continue;
+        });
+    }
+
     for_each_toolbar_button([checked](GButton& button) {
         button.set_checked(checked);
     });
@@ -112,3 +124,8 @@ void GAction::set_checked(bool checked)
         item.set_checked(checked);
     });
 }
+
+void GAction::set_group(Badge<GActionGroup>, GActionGroup* group)
+{
+    m_action_group = group ? group->make_weak_ptr() : nullptr;
+}

Libraries/LibGUI/GAction.h

@@ -11,6 +11,7 @@
 #include <LibGUI/GShortcut.h>
 #include <SharedGraphics/GraphicsBitmap.h>
 
+class GActionGroup;
 class GButton;
 class GMenuItem;
 class GWidget;
@@ -70,6 +71,9 @@ public:
     void register_menu_item(Badge<GMenuItem>, GMenuItem&);
     void unregister_menu_item(Badge<GMenuItem>, GMenuItem&);
 
+    const GActionGroup* group() const { return m_action_group.ptr(); }
+    void set_group(Badge<GActionGroup>, GActionGroup*);
+
 private:
     GAction(const StringView& text, Function<void(GAction&)> = nullptr, GWidget* = nullptr);
     GAction(const StringView& text, const GShortcut&, Function<void(GAction&)> = nullptr, GWidget* = nullptr);
@@ -92,4 +96,5 @@ private:
     HashTable<GButton*> m_buttons;
     HashTable<GMenuItem*> m_menu_items;
     WeakPtr<GWidget> m_widget;
+    WeakPtr<GActionGroup> m_action_group;
 };

Libraries/LibGUI/GActionGroup.cpp

@@ -0,0 +1,14 @@
+#include <LibGUI/GAction.h>
+#include <LibGUI/GActionGroup.h>
+
+void GActionGroup::add_action(GAction& action)
+{
+    action.set_group({}, this);
+    m_actions.set(&action);
+}
+
+void GActionGroup::remove_action(GAction& action)
+{
+    action.set_group({}, nullptr);
+    m_actions.remove(&action);
+}

Libraries/LibGUI/GActionGroup.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <AK/HashTable.h>
+#include <AK/Weakable.h>
+
+class GAction;
+
+class GActionGroup : public Weakable<GActionGroup> {
+public:
+    GActionGroup() {}
+    ~GActionGroup() {}
+
+    void add_action(GAction&);
+    void remove_action(GAction&);
+
+    bool is_exclusive() const { return m_exclusive; }
+    void set_exclusive(bool exclusive) { m_exclusive = exclusive; }
+
+    bool is_unchecking_allowed() const { return m_unchecking_allowed; }
+    void set_unchecking_allowed(bool unchecking_allowed) { m_unchecking_allowed = unchecking_allowed; }
+
+    template<typename C>
+    void for_each_action(C callback)
+    {
+        for (auto& it : m_actions) {
+            if (callback(*it) == IterationDecision::Break)
+                break;
+        }
+    }
+
+private:
+    HashTable<GAction*> m_actions;
+    bool m_exclusive { false };
+    bool m_unchecking_allowed { false };
+};

Libraries/LibGUI/GButton.cpp

@@ -1,7 +1,8 @@
-#include "GButton.h"
 #include <AK/StringBuilder.h>
 #include <Kernel/KeyCode.h>
 #include <LibGUI/GAction.h>
+#include <LibGUI/GActionGroup.h>
+#include <LibGUI/GButton.h>
 #include <LibGUI/GPainter.h>
 #include <SharedGraphics/StylePainter.h>
 
@@ -60,8 +61,11 @@ void GButton::click()
 {
     if (!is_enabled())
         return;
-    if (is_checkable())
+    if (is_checkable()) {
+        if (is_checked() && !is_uncheckable())
+            return;
         set_checked(!is_checked());
+    }
     if (on_click)
         on_click(*this);
 }
@@ -88,3 +92,12 @@ void GButton::set_icon(RefPtr<GraphicsBitmap>&& icon)
     m_icon = move(icon);
     update();
 }
+
+bool GButton::is_uncheckable() const
+{
+    if (!m_action)
+        return true;
+    if (!m_action->group())
+        return true;
+    return m_action->group()->is_unchecking_allowed();
+}

Libraries/LibGUI/GButton.h

@@ -34,6 +34,7 @@ public:
     virtual const char* class_name() const override { return "GButton"; }
     virtual bool accepts_focus() const override { return m_focusable; }
     virtual bool supports_keyboard_activation() const override;
+    virtual bool is_uncheckable() const override;
 
     void set_focusable(bool b) { m_focusable = b; }
 

Libraries/LibGUI/Makefile

@@ -27,6 +27,7 @@ LIBGUI_OBJS = \
     GMenuItem.o \
     GApplication.o \
     GAction.o \
+    GActionGroup.o \
     GFontDatabase.o \
     GToolBar.o \
     GTableView.o \