LibGUI+LibDraw: Add "Palette" concept for scoped color theming

GApplication now has a palette. This palette contains all the system
theme colors by default, and is inherited by a new top-level GWidget.
New child widgets inherit their parents palette.

It is possible to override the GApplication palette, and the palette
of any GWidget.

The Palette object contains a bunch of colors, each corresponding to
a ColorRole. Each role has a convenience getter as well.

Each GWidget now has a background_role() and foreground_role(), which
are then looked up in their current palette when painting. This means
that you no longer alter the background color of a widget by setting
it directly, rather you alter either its background role, or the
widget's palette.

1 files changed, 10 insertions, 0 deletions

diff --git a/Libraries/LibGUI/GApplication.h b/Libraries/LibGUI/GApplication.h
index ad8e57e76e..539ebef04f 100644
--- a/Libraries/LibGUI/GApplication.h
+++ b/Libraries/LibGUI/GApplication.h
@@ -10,7 +10,10 @@ class GAction;
 class GKeyEvent;
 class GMenuBar;
 class GWindow;
+class GWindowServerConnection;
+class Palette;
 class Point;
+class SharedBuffer;
 
 class GApplication {
 public:
@@ -39,9 +42,16 @@ public:
     const String& invoked_as() const { return m_invoked_as; }
     const Vector<String>& args() const { return m_args; }
 
+    const Palette& palette() const { return *m_palette; }
+    void set_palette(const Palette&);
+
+    void set_system_palette(SharedBuffer&);
+
 private:
     OwnPtr<CEventLoop> m_event_loop;
     OwnPtr<GMenuBar> m_menubar;
+    RefPtr<Palette> m_palette;
+    RefPtr<Palette> m_system_palette;
     HashMap<GShortcut, GAction*> m_global_shortcut_actions;
     class TooltipWindow;
     TooltipWindow* m_tooltip_window { nullptr };