LibGUI: Make Layout a Core::Object and add basic serialization

This allows you to view layouts (as data) in Inspector.

Libraries/LibGUI/BoxLayout.cpp

@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <AK/JsonObject.h>
 #include <LibGUI/BoxLayout.h>
 #include <LibGUI/Widget.h>
 #include <LibGfx/Orientation.h>
@@ -174,4 +175,10 @@ void BoxLayout::run(Widget& widget)
     }
 }
 
+void BoxLayout::save_to(JsonObject& json)
+{
+    Layout::save_to(json);
+    json.set("orientation", m_orientation == Gfx::Orientation::Vertical ? "Vertical" : "Horizontal");
+}
+
 }

Libraries/LibGUI/BoxLayout.h

@@ -33,19 +33,25 @@
 namespace GUI {
 
 class BoxLayout : public Layout {
+    C_OBJECT(BoxLayout);
 public:
-    explicit BoxLayout(Gfx::Orientation);
     virtual ~BoxLayout() override {}
 
     Gfx::Orientation orientation() const { return m_orientation; }
 
     virtual void run(Widget&) override;
 
+protected:
+    explicit BoxLayout(Gfx::Orientation);
+
+    virtual void save_to(JsonObject &) override;
+
 private:
     Gfx::Orientation m_orientation;
 };
 
 class VerticalBoxLayout final : public BoxLayout {
+    C_OBJECT(VerticalBoxLayout);
 public:
     explicit VerticalBoxLayout()
         : BoxLayout(Gfx::Orientation::Vertical)
@@ -55,6 +61,7 @@ public:
 };
 
 class HorizontalBoxLayout final : public BoxLayout {
+    C_OBJECT(HorizontalBoxLayout);
 public:
     explicit HorizontalBoxLayout()
         : BoxLayout(Gfx::Orientation::Horizontal)

Libraries/LibGUI/Layout.cpp

@@ -25,6 +25,7 @@
  */
 
 #include <AK/Badge.h>
+#include <AK/JsonObject.h>
 #include <LibGUI/Layout.h>
 #include <LibGUI/Widget.h>
 
@@ -120,4 +121,32 @@ void Layout::set_margins(const Margins& margins)
         m_owner->notify_layout_changed({});
 }
 
+void Layout::save_to(JsonObject& json)
+{
+    Core::Object::save_to(json);
+    json.set("spacing", m_spacing);
+
+    JsonObject margins_object;
+    margins_object.set("left", m_margins.left());
+    margins_object.set("right", m_margins.right());
+    margins_object.set("top", m_margins.top());
+    margins_object.set("bottom", m_margins.bottom());
+    json.set("margins", move(margins_object));
+
+    JsonArray entries_array;
+    for (auto& entry : m_entries) {
+        JsonObject entry_object;
+        if (entry.type == Entry::Type::Widget) {
+            entry_object.set("type", "Widget");
+            entry_object.set("widget", (uintptr_t)entry.widget.ptr());
+        } else if (entry.type == Entry::Type::Spacer) {
+            entry_object.set("type", "Spacer");
+        } else {
+            ASSERT_NOT_REACHED();
+        }
+        entries_array.append(move(entry_object));
+    }
+    json.set("entries", move(entries_array));
+}
+
 }

Libraries/LibGUI/Layout.h

@@ -29,14 +29,16 @@
 #include <AK/OwnPtr.h>
 #include <AK/Vector.h>
 #include <AK/WeakPtr.h>
+#include <LibCore/Object.h>
 #include <LibGUI/Forward.h>
 #include <LibGUI/Margins.h>
 
 namespace GUI {
 
-class Layout {
+class Layout : public Core::Object {
+    C_OBJECT_ABSTRACT(Layout);
+
 public:
-    Layout();
     virtual ~Layout();
 
     void add_widget(Widget&);
@@ -57,7 +59,11 @@ public:
     int spacing() const { return m_spacing; }
     void set_spacing(int);
 
+    virtual void save_to(JsonObject&) override;
+
 protected:
+    Layout();
+
     struct Entry {
         enum class Type {
             Invalid = 0,

Libraries/LibGUI/Splitter.cpp

@@ -36,7 +36,7 @@ Splitter::Splitter(Orientation orientation)
     : m_orientation(orientation)
 {
     set_background_role(ColorRole::Button);
-    set_layout(make<BoxLayout>(orientation));
+    set_layout<BoxLayout>(orientation);
     set_fill_with_background_color(true);
     layout()->set_spacing(4);
 }

Libraries/LibGUI/ToolBar.cpp

@@ -44,7 +44,7 @@ ToolBar::ToolBar(Orientation orientation, int button_size)
         set_size_policy(SizePolicy::Fixed, SizePolicy::Fill);
         set_preferred_size(button_size + 12, 0);
     }
-    set_layout(make<BoxLayout>(orientation));
+    set_layout<BoxLayout>(orientation);
     layout()->set_spacing(0);
     layout()->set_margins({ 2, 2, 2, 2 });
 }

Libraries/LibGUI/Widget.cpp

@@ -242,12 +242,15 @@ void Widget::handle_paint_event(PaintEvent& event)
     second_paint_event(event);
 }
 
-void Widget::set_layout(OwnPtr<Layout>&& layout)
+void Widget::set_layout(NonnullRefPtr<Layout> layout)
 {
-    if (m_layout)
+    if (m_layout) {
         m_layout->notify_disowned({}, *this);
+        m_layout->remove_from_parent();
+    }
     m_layout = move(layout);
     if (m_layout) {
+        add_child(*m_layout);
         m_layout->notify_adopted({}, *this);
         do_layout();
     } else {

Libraries/LibGUI/Widget.h

@@ -96,13 +96,14 @@ public:
 
     Layout* layout() { return m_layout.ptr(); }
     const Layout* layout() const { return m_layout.ptr(); }
-    void set_layout(OwnPtr<Layout>&&);
+    void set_layout(NonnullRefPtr<Layout>);
 
-    template<typename T>
+    template<class T, class... Args>
-    T& set_layout()
+    inline T& set_layout(Args&&... args)
     {
-        set_layout(make<T>());
+        auto layout = T::construct(forward<Args>(args)...);
-        return static_cast<T&>(*layout());
+        set_layout(*layout);
+        return layout;
     }
 
     SizePolicy horizontal_size_policy() const { return m_horizontal_size_policy; }
@@ -304,7 +305,7 @@ private:
     void focus_next_widget();
 
     Window* m_window { nullptr };
-    OwnPtr<Layout> m_layout;
+    RefPtr<Layout> m_layout;
 
     Gfx::Rect m_relative_rect;
     Gfx::ColorRole m_background_role;