LibGUI: Start adding an automatic widget layout system.

My needs are really quite simple, so I'm just going to add what I need
as I go along. The first thing I needed was a simple box layout with
widgets being able to say whether they prefer fixed or fill for both
their vertical and horizontal sizes.

I also made a simple GStatusBar so FileManager can show how many bytes
worth of files are in the current directory.

SharedGraphics/Painter.cpp

@@ -4,7 +4,7 @@
 #include <AK/Assertions.h>
 #include <AK/StdLibExtras.h>
 
-#ifdef LIBGUI
+#ifdef USERLAND
 #include <LibGUI/GWidget.h>
 #include <LibGUI/GWindow.h>
 #include <LibC/gui.h>
@@ -20,7 +20,7 @@ Painter::Painter(GraphicsBitmap& bitmap)
     m_clip_rect = { { 0, 0 }, bitmap.size() };
 }
 
-#ifdef LIBGUI
+#ifdef USERLAND
 Painter::Painter(GWidget& widget)
     : m_font(&widget.font())
 {
@@ -34,9 +34,9 @@ Painter::Painter(GWidget& widget)
     m_target = GraphicsBitmap::create_wrapper(backing.size, backing.pixels);
     ASSERT(m_target);
     m_window = widget.window();
-    m_translation.move_by(widget.relative_position());
+    m_translation.move_by(widget.window_relative_rect().location());
     // NOTE: m_clip_rect is in Window coordinates since we are painting into its backing store.
-    m_clip_rect = widget.relative_rect();
+    m_clip_rect = widget.window_relative_rect();
     m_clip_rect.intersect(m_target->rect());
 
 #ifdef DEBUG_WIDGET_UNDERDRAW
@@ -49,7 +49,7 @@ Painter::Painter(GWidget& widget)
 
 Painter::~Painter()
 {
-#ifdef LIBGUI
+#ifdef USERLAND
     m_target = nullptr;
     int rc = gui_release_window_backing_store(m_backing_store_id);
     ASSERT(rc == 0);

SharedGraphics/Rect.h

@@ -52,6 +52,16 @@ public:
         return { x() + width() / 2, y() + height() / 2 };
     }
 
+    void set_location(const Point& location)
+    {
+        m_location = location;
+    }
+
+    void set_size(const Size& size)
+    {
+        m_size = size;
+    }
+
     void inflate(int w, int h)
     {
         set_x(x() - w / 2);

SharedGraphics/Size.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <AK/AKString.h>
+
 struct GUI_Size;
 
 class Size {
@@ -29,8 +31,17 @@ public:
         return !(*this == other);
     }
 
+    Size& operator-=(const Size& other)
+    {
+        m_width -= other.m_width;
+        m_height -= other.m_height;
+        return *this;
+    }
+
     operator GUI_Size() const;
 
+    String to_string() const { return String::format("[%d,%d]", m_width, m_height); }
+
 private:
     int m_width { 0 };
     int m_height { 0 };