LibGUI: Add foreground_role and background_role property to GUI::Widget

These properties allow GML files to specify a Gfx::ColorRole instead of
a color, so that the effective color of the Widget is resolved using the
system theme.

Userland/Libraries/LibGUI/Widget.cpp

@@ -21,6 +21,7 @@
 #include <LibGfx/Font.h>
 #include <LibGfx/FontDatabase.h>
 #include <LibGfx/Palette.h>
+#include <LibGfx/SystemTheme.h>
 #include <unistd.h>
 
 REGISTER_CORE_OBJECT(GUI, Widget)
@@ -136,6 +137,50 @@ Widget::Widget()
  }
  return false;
  });
+
+ register_property(
+ "foreground_role", [this]() -> JsonValue { return Gfx::to_string(foreground_role()); },
+ [this](auto& value) {
+ if (!value.is_string())
+ return false;
+ auto str = value.as_string();
+ if (str == "NoRole") {
+ set_foreground_role(Gfx::ColorRole::NoRole);
+ return true;
+ }
+#undef __ENUMERATE_COLOR_ROLE
+#define __ENUMERATE_COLOR_ROLE(role) \
+ else if (str == #role) \
+ { \
+ set_foreground_role(Gfx::ColorRole::role); \
+ return true; \
+ }
+ ENUMERATE_COLOR_ROLES(__ENUMERATE_COLOR_ROLE)
+#undef __ENUMERATE_COLOR_ROLE
+ return false;
+ });
+
+ register_property(
+ "background_role", [this]() -> JsonValue { return Gfx::to_string(background_role()); },
+ [this](auto& value) {
+ if (!value.is_string())
+ return false;
+ auto str = value.as_string();
+ if (str == "NoRole") {
+ set_background_role(Gfx::ColorRole::NoRole);
+ return true;
+ }
+#undef __ENUMERATE_COLOR_ROLE
+#define __ENUMERATE_COLOR_ROLE(role) \
+ else if (str == #role) \
+ { \
+ set_background_role(Gfx::ColorRole::role); \
+ return true; \
+ }
+ ENUMERATE_COLOR_ROLES(__ENUMERATE_COLOR_ROLE)
+#undef __ENUMERATE_COLOR_ROLE
+ return false;
+ });
 }
 
 Widget::~Widget()